CP

Diffraction ( Snell's Law)

Diffraction is the bending of a wave around a corner or obstacle.

Electron Capture

A proton is changed into a neutron via capture of an electron.

Alpha Decay

The loss of one He nucleus, which has a mass number of 4 and atomic number of 2 Mass accounts for protons

Molar mass

The mass in grams of 1 mol of a substance.

Chromatography

Separation of one or more compounds by dissolving them in a mobile phase and passing that phrase through or across a stationary phase Substances in mobile phase interact to varying degrees based on their polarity More interaction= slower movement Substances that do not interact will move out fastest The first substance out of the tube will be the LEAST polar

Improving Separation

Seperation can be aided by repitation Fractional Extraction: Extracting with 5 mL 10 separate times will produce a much better separation than extracting with 50 mL all at once Addition of an acid to protonate the product Addition of a base to deprotonate the product DON'T MIX VIGOROUSLY, DON'T USE REACTIVE SOLVENTS, DON'T USE HIGH BOILING POINT Assume that non-polar layer is less dense and will ALWAYS be on top Polar products are expected to be in the bottom layer and non polar products on the top layer

Simple Machines

Simple machines reduce the amount of force necessary to perform a given amount of work Machines NEVER reduce or change the amount of WORK --- work required and it is independent of any machine used, or the path taken. Work isn't changing, work is just change of energy Without a machine: -- Determine the amount of force necessary to lift or move an object without a machine --- Compare this force to the force necessary with the machine --- Two values will differ by an exact ratio (H/d, L1/L2), ex- a ratio of 1/5 gives 5X machine that reduces the force necessary by a factor of 5, aka Mechanical advantage of 5 ----- Or this means it allows a person capable of a maximum Force, F, to create a force of 5F when using the machine ----THE FORCE NECESSARY TO LIFT A MASS WITHOUT A MACHINE (at a constant velocity)- F (necessary)= mg

Dielectric

Substance between two plates All capacitors have a dielectric, even if it just air Other dielectrics are often insterted between the plates, such as gels or composites When inserted, some energy store in capacitor is used to align the polar molecules in the dielectric (dipoles) with the field between the plates Increasing strength of dielectric, increases the capacitance, thus allows more charge and energy to be stored INCREASING DIELECTRIC STRENGTH, INCREASES CAPACITANCE, dielectrics decrease voltage, so looking at C=Q/V, when you decrease voltage, you increase capacitance. Dielectric must ALWAYS be an insulator inorder to discharge the capacitor to allow electrons to flow between the plates

Tension Forces

Tension is the force in a rope, string, cable, etc. In most cases, you can ignore tension by replacing it with a force vector on the object to which the rope, string, or cable is attached. o Q37. What is the tension in a rope being pulled from opposite ends with identical forces of 50 N? - 50 N o Q38. A 500 kg elevator is being accelerated upward by a cable with a tension of 6,000 N. What force does the elevator exert on the cable? -According to Newton's Third Law, if the elevator cable is pulling on the elevator with 6,000 N of force, the elevator must be pulling on the rope with a force of 6,000 N.

The Common-Ion Effect:

The Common Ion Effect is a specific application of Le Chatelier's principle to solution chemistry. Consider the dissolution of Iron(III)Chloride in water: FeCl3(s) ↔ Fe3+(aq) + 3Cl- (aq). Suppose that enough solute is added to saturate the solution. If sodium nitrate is then added to this solution it would have no effect. However, if NaCl were added, the presence of extra chlorine ions from NaCl would—according to LeChatelier's Principle—drive the reaction to the left resulting in precipitation. In this example, chloride is considered a "common ion" and the precipitation as a result of its addition is what is referred to as the "Common Ion Effect." Other ions, such as sodium and nitrate—that do not shift the equilibrium—are considered "spectator ions."

Heisenberg Uncertainity

The Heisenberg Uncertainty Principles states that the more we know about an electron's position, x, the less we know about its momentum, p.

Newton's First Law-

The Law of Inertia Law of Inertia: An object in motion tends to stay in motion (in the same direction and at the same speed), and an object at rest tends to stay at rest, unless acted upon by some net external force. A simplified version could be: Objects with a constant velocity maintain a constant velocity unless acted upon by a net outside force. This mean there is a NET force of 0, there is NO net force pushing this to accelerate. An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Inertia is the ability of an object to resist a change to it's velocity and mass is a measure of an object's inertia The center of mass is a weighted average of mass distribution and we calculate it through this formula: Cmass = (r1m1 + r2m2 + r3m3 . . . )/mtotal. - r is the displacement vector getween a reference point and each mass, ALWAYS CHOOSE YORU REFERENCE POINT FIRST, - if you choose the reference point of one mass, it's r will drop

Kinetic Theory of Gases

The MCAT authors have shown a clear affinity for test questions that address the contrasts between "ideal" behavior and real behavior We compare ideal behavior vs real behavior KNOW THE FOLLOWING: - cALCULATING A PROJECTICLE'S MOTION IGNORING AIR RESISTANCE but also how it is changed uner real conditions - THis is similar when dealing with ideal fluids vs real fluids - Ideal gases vs real gases

Heat Capacity

The amount of energy (Joules or Calories) a system must absorb to give a unit change in temperature (J/K or cal/˚C). THIS IS FOR A SYSTEM think of heat capacity as "the amount of energy we can add before the system increases by one temperature unit," So when something can hold more energy before Temperature change, it means that it has a higher heat capacity C = q/∆T C= heat capacity q= heat or energy ∆T= Change in temperature q>0 If heat is added to the system q< If heat leaves the system

ΔHfusion

The amount of energy in Joules/mole required to go from solid to liquid or the energythat must be removed to go from liquid to solid. This describes the transition in both directions (i.e., melting and freezing). Solid to liquid= melting liquid to solid= freezing

ΔHsolution

The enthalpy value associated with the dissolution of a species into solution The enthalpy change of solution is the enthalpy change when 1 mole of an ionic substance dissolves in water to give a solution of infinite dilution.

Half Life Problems

The half-life of a substance (t1/2) is the amount of time required for exactly one-half of the mass of that substance to disappear due to radioactive decay.

Lanthanides

The upper row in the f-block

Dual Nature

The wave model of light supposes that light is a wave. Young's Double Slit Experiment provides support for this model because only waves would show the diffraction and interference patterns necessary to create the characteristic light and dark bands. The particle model of light supposes that light is a particle. The photoelectric effect is the major support for this model. The two are reconciled by quantum mechanics: photons are described by "wave functions" which sometimes act as macroscopic waves and sometimes as macroscopic particles.

Rate Order Graphs

These graphs will only be linear when the reaction has only a single reactant, OR when it is part of a multiple-reactant reaction where the rate is independent of ALL the other reactants (e.g., the other reactant is zero order, or is in excess) Zero Order, First Order, Second Order. Something is ONLY LINEAR when there is ONE reactant, and it's the only one that has an effect.

Projectile Motion

Think of projectile motion as nothing more than falling body problems in two dimensions. Immediately resolve the given vectors into components; then solve in your head as you would any other motion problem "Range," or horizontal distance traveled, is a new value asked for in projectile motion. It is the product of velocity in the x-direction (Vx) and time (t). - Range = Vxt When you see projectile motion, THINK: 1) Horizontal velocity never changes (as long as you are ignoring air resistance) 2) Horizontal acceleration always = 0 3) Vertical acceleration always = 10 m/s2 downward 4) Vertical behavior is exactly symmetrical (i.e., if ignoring air resistance, a projectile's upward trip is identical to its downward trip) 5) Time in the air depends on the vertical component of velocity only 6) Range depends on both the vertical and horizontal components of velocity 7) Time is always the same for both the x and y components of the motion.

Titration Curves: Weak Base with Strong Acid

This will look like the strong base/strong acid titration except the pH will not start as high, the equivalence region won't last for as many pH units, and the equivalence point will be at a pH below 7. For WB w/ SA: pH < 7

Resolving Vectors into Components- WRT X-axis

X Component- Vcos (angle) Y Component- Vsin (angle)

Saturated Solution

a solution that contains the maximum amount of dissolved solute it can hold. For a saturated solution the ion product equals the Ksp.

How does the addition of a volatile solute affect vapor pressure?

When a volatile solute is added to a solvent it usually decreases vapor pressure for the same reason that a non-volatile solute decreases vapor pressure. As long as the vapor pressure of the solute is LESS THAN the vapor pressure of pure solvent, addition of the volatile solute will decrease vapor pressure. However, if a solute is added that has a vapor pressure greater than that of the pure solvent, then the vapor pressure of the solution will actually be higher than that of the pure solvent. This can be seen by simple examination of the formula for calculating the vapor pressure of a solution containing a volatile solute: Vp = (Xsolute*Vpsolute) + (Xsolvent*Vpsolvent).

Recrystallization

When the desired product that still contains impurities is dissolved in the minimum amount of hot solvent necessary to create solution The solution is then cooled as slowly as possible Because pure substances usually crystallize at a higher temperature than impure substances, if the temp drops below melting point of the product, crystals form and the impurities remain in solution Higher and sharper melting points indicate better purity. Impurities lower melting point. They also broaden the range across which the crystals melt.

Solving Ideal Gas Law Problems

Whenever you see more than one of the above variables together in the same problem (i.e., T, P, n and/or V), you are most likely dealing with an Ideal Gas Law problem. There are two ways you can approach these problems: 1) Manipulating Equations- PV=nRT 2) P1V1/T1 = P2V2/T2 (combined gas Law --Because PV/T = nR, and R is a constant, given the same number of moles of gas, the ratio of PV/T must remain constant, regardless of the changes made to the system. -- You can choose the first set of data as being STP, or as any other point where P, V and T are known. The second set of data will be different, but the ratio will always be the same. --- Plug in the data and solve for the unknown. Conceptually, you're probably better off if you understand and can apply the first method.

Transition Metals

Transition metals are the elements in the four middle rows.

tair= 2V/g

Used only to calculate "round trip" times, or in other words, the total time in the air. The variable V must be the vertical component of initial velocity

Titration Curves: Strong Base with Strong Acid

With strong base present, the pH will start high. As strong acid is added, it will slowly go to lower pH and then sharply drop when the equivalence point is reached. Again, the middle of the pH region will be pH 7. It will then slowly go to lower pH as more strong acid is added. For SA w/ SB: pH =7

Snell's Law

n₁sinθ₁=n₂sinθ₂ a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic medium, such as water, glass, or air. Ray P is an incident ray, Ray Q is a refracted ray, and Ray R is a reflected ray. The angle θ1 is always exactly equal to the angle θ3. The angles θ1 and θ2 are related to one another according to Snell's Law. Based on the direction of refraction alone, we know that n1 < n2. Because light waves travel faster in lower index mediums, we also know that v1 > v2. --- LIGHT TRAVELS FASTER IN LOWER n's.... --- low n= bigger v If we were to assume that the end of the blue shaded region represents the end of that medium, and that the white region below it represents a return to the same medium in which Rays P and R are traveling, then a continuation of Ray Q through this interface would create a newly refracted ray, Ray S. Ray S would be parallel to, but not continuous with, Ray P.

Combination Reaction

also known as a synthesis reaction in chemistry is when two or more substances, or reactants, combine with each other to form a new product. The product will always be a compound.

Know how to convert Celsius to Kelvin

always use Kelvin in formulas, unless Celsius is specified.

The Law of Mass Action

o Keq = [products]x/[reactants]y -the molarity values are the exponents... o Keq is written with every term raised to an exponent equal to its coefficient in the balanced equation (remember, however, that you do NOT do this when writing rate laws). Pure liquids (ℓ) and pure solids (s) are never included! Usually done in molarity, which moles/Liters How does each of the following affect equilibrium: addition of a catalyst- Does nothing to equilibirum increased temperature-exo rxn decrease Keq and endo rxn increase Keq, lowering the Ea-Lowering energy of activation impacts rate, NOT equilibrium stabilizing the transition state- same thing as EA addition of reactants/products- Does nothing to equilibirum, "temperature is the only thing that changes Keq."

Halogenation of an Aldehyde or Ketone

o Substitution of a Br, Cl or I for one of the alpha hydrogens on an aldehyde or ketone. Multiple halogenations often occur. o STEPS: 1) A base abstracts an alpha hydrogen, leaving a carbanion. 2) The carbanion attacks a diatomic halogen.

Salt of Weak Base

the "salt of a weak base" refers to the conjugate acid of that weak base combined with an anion to form a salt conjugate acid +Anion for weak bases NH3 = "weak base"; NH4+ = "conjugate acid"; NH4NO3 = "salt of a weak base" NO3- is the anion combining with the conjugate acid of NH4+ When the salts of weak acids or weak bases dissolve in water one of the ions will undergo hydrolysis to re-form the weak acid or the weak base: 1) NH4NO3 <-> NH4+ + NO3^2- 2) NH4+ + H2O <-> NH3 + H3O+

pH Scale

the pH scale ranks solutions based not so much on the acids or bases themselves, but on how those acids or bases influence the equilibrium for the ionization of water.

T = 2pi√(m/k)

the period for a mass on a spring m is the mass k is the spring constant

T=2pi√(L/g)

the period for pendulum L is the length of the Pendulum

Critical Temperature

the temperature at the critical pont temp at the critical point; above this temp the vapor can't be liquified at any pressure

Isomers

two molecules are isomers if they have the same molecular formula but are actually different compounds The maximum number of optically active stereoisomers for any compound = 2^n, where n is the number of chiral centers.

E1, SN1, E2, SN2 Summaries

when something is less nucleophilic in protic solution, it means that in a protic solution that has high concentrations of Hydrogens, it doesn't react well. The hydrogens keep the nucleophile shielded, thus it cannot attack take into account how stearic hindrance affects the raction polar protic solvents favor E1 and SN1 polar aprotic solvents favor SN2, increases strength of nucleophile

X = (½)at^2

x is distance a is acceleration t is time

Calculating ΔH from a heating curve:

ΔHfusion = The change in q (x-axis) during the phase change from solid to liquid. ΔHvaporization = The change in q (x-axis) during the phase change from liquid to gas.

normality

# of moles of equivalents/Liter solution. For example, a 1M solution of H2SO4 can be referred to as a "2 Normal" solution because it produces two moles of hydronium ions per Liter of solution. By the same token, a 2M solution of H3PO4 3- would be a "6 Normal" solution with respect to hydronium ions. This concept ignores the decreasing acidity of each proton. Some chemists discourage the use of this measure, but it has been used on the MCAT—albeit rarely. the concentration of a a solution given in equivalents of solute per liter of solution

Frequency

# of waves that pass a point in a given amount of time Sound Power number of wavelengths that pass a fixed point each second (units = 1/s or s-1 or Hertz [Hz]). Period and frequency are always inverses of each other Waves have power due to trasnfering energy from one location to another. The intensity of any sound or mechanical wave is directly proportional to the amplitude squared and the frequency squared: --- I= A²f² Units= W/m² Many waves such as sound, travel outward form their origin in all directions, due to this, intensity is measured per square meter, and magnitude decreases as area of sphere increases: ---A=4πr²

Solubility of Common Compounds

Remembering the following general rules will give you a quick shortcut to the right answer on several problems. 1) All compounds containing the following are SOLUBLE: nitrate, ammonium, and all alkali metals (Group IA). 2) All compounds containing the following are INSOLUBLE: (unless paired with something from the "always soluble" list above) carbonate, phosphate, silver (Ag), mercury (Hg), and lead (Pb).

Chlorate

ClO3-

How to fill electron orbitals

Make sure students are familiar with the traditional order of progressing through the periodic table to fill orbitals. 1) between the s-block and d-block, where they need to know that the first d-block row is a 3d even though the orbital filled just prior to it was a 4s, 2) between the s-block, f-block, and d-block in rows 6 and 7; where they need to know that the lanthanide and actinide series are filled before proceeding with rows 6 and 7 respectively

Column Chromatography

Mixture to be separated through a column packed with charged glass beads or some other polar matrix Solution is collected in fractions at the bottom of the column involves a stationary phase of finely-divided alumina or silica gel in a vertical glass tube and an organic solvent as the moving phase Most non-polar substances elute out first in polar matrixes Then more polar substances follow

Q38. Why can you usually ignore the rate law for the uncatalyzed reaction?

The uncatalyzed reaction usually proceeds at a rate that is much slower than the catalyzed reaction. Therefore, the products from the reaction will be almost exclusively result from the catalyzed pathway. We can ignore the parallel uncatalyzed reaction because even though we know it is occurring simultaneously, its contribution to the progress of the reaction is negligible.

PE = (1/2)k∆x2

This in relation to Hooke's law F = k∆x When there are multiple springs, the PE is distributed to each spring. For example, if a truck spring has a spring constant of 5X10^4 N/m and when it is unloaded, it is .8m above the ground, when loaded, it is lowered to .7m above the ground, how much PE is stored in 4 springs? After you do the math, you end up with 250 joules, but it is multiplied by 4, for each of the springs.

Entropy

a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.

Buoyant Force

Where v is the volume of fluid displaced, NOT the total volume of the fluid, and ρ is the density of the fluid, NOT the object the buoyant force is always exactly equal to the weight of the amount of fluid displaced by the object. Buoyant force will increase until the object is full submerged.

Color Shifts

White light will shift blue if the doppler effect causes a perceived INCREASE in frequency (perceived decrease in wavelength) White light will shift red if the doppler effect causes a perceived decrease in frequency (perceived increase in wavelength)

Resolving Vectors into components- WRT Y-axis

X Component- Vsin (angle) Y component- Vcos (angle)

Zero Order

[A] vs. time is linear (i.e., yields a straight line) with slope = -k zero order is not included in the rate law, so if [A]^0, then the rate law would only be be shown as R=K Putting it in excess makes it effectively zero order under those conditions and any effect remaining must be due solely to only ONE reactant

Ethers

AN oxygen bonded to two R-groups in the R-O-R format Nomeclature- ethers referred by common names wherein each -R group is named separately (Methyl ethyl ether, dietheylether, methyl propyl ether IUPAC- STandard naming of longer of 2 -R groups as the parent chain, naming the other -R group with a substituent with oxy added (1-ethoxyhepatne) VERY NON REACTIVE weakly polar short-R groups slightyl soluble in water Most non-polar species are soluble in ethers Low boiling point (no H-bonding) EXCELLENT SOLVENT due to these properties IF ethers do react, it will only be after the oxygen is protonated by a strong acid, resulting in a unstable intermediate that can be attacked by a nucleophile

Amides

Any compound containg a carbonyl with an anime sbustituent Nomeclature- change oic ending to amide- ex- benzoic Acid-> benzamide Properties: --- Most stable of all acid derivatives, for MCAT, carbonyl carbons are unreactive cause NH2 is NOT good leaving group --- Primary and secondary amides can hydrogen bond, but not tertiary amides --- Resonance (double bond character) limits rotation due to the lone pair on the amide nitrogen, it resonates with carbonyl double bond, via SP2 character --- less basic than amines due to conjugated system, less electron density

Second Law of Thermodynamics

o Heat cannot be changed completely into work in a cyclical process. o Entropy in an isolated system can never decrease- the disorder will never decrease -Heat will never flow spontaneously from colder object to a hotter object. example- when we have an ice cube on our hand, we don't feel the cold, but we feel heat loss from our hand because heat is being transferred into the ice cube.

Nernst Equation

E= E° - (.06/n) * log [lower]/[higher] n= Moles of e- transferred example- Fe³⁺ (aq) → Fe(s) = 3 moles of e- being transferred, or if it is Ag⁺ (aq)→(Ag(s), then 1 mole of e- is transferred. Remember that E°Cell for a concentration cell, will ALWAYS equal 0, because you are using the same species for both the anode and cathode, for the reduction and oxidation half equation

Radiation

Electromagnetic waves emitted from a hot body into the surrounding environment Charged particles being accelerated, they release electromagnetic acceleration. There is acceleration of charged particles and that releases electromagnetic radiation. The light you see from the fire is electromagnetic radiation that you can see. Light colors radiate and absorb less Dark colors radiate and absorb more A black body radiator- A thermal electromagnetic radiator that is within or surrounding a body in thermodynamic equilibrium with its environment. It has a specific spectrum and intensity that depends only on the body's temperature- theoretically perfect body that absorbs all energy incident upon it (or produced within it) and then emits 100% of this energy as electromagnetic radiation

Electron Configuration

Electron configurations are a list of quantum numbers and the number of electrons in each Energy level diagrams are the stair-step diagrams you drew in general chemistry with lines representing orbitals and up and down arrows representing electrons Orbitals are filled from low to high, always in order, so 1st to 2s, so on and so forth example- Carbon- 1s^2,2s^2,2p^2 hydrogen- 1s^1, Helium is 1s^2 Li- 1s^2, 2s^1 N=1s^2,2s^2,2p^3 Si=1s^2, 2s^2, 2p^6, 3s^2, 3p^2 NOble gas config example- Si=1s^2, 2s^2, 2p^6, 3s^2, 3p^2= [Ne] 3s^23p^2 Ni=1s^2,2s^2,2p^6,3s^2,3p^6, 4s^2, 3d^8: noble gas config= [Ar] 4s^2, 3d^8 -The 4s^2 is the valence electrons... The only remotely difficult MCAT question you'll face regarding electron configuration is to provide the configuration for cations and anions. For cations, move back one box in the periodic table for each electron missing. Ca^2+= [Ar] For anions, move forward one box for each extra electron.

Coordinate Covalent Bonds

: A covalent bond in which both electrons shared in the bond are donated by one atom. In most cases, more than one of these "donor" molecules surround and bind a single "recipient" molecule. The donor molecule must have a lone pair and the recipient molecule must have an empty orbital. ***If a molecule does not have a lone pair of electrons it CANNOT form coordinate covalent bonds with metals or other Lewis acids. The complex formed by the metal and the molecules forming coordinate covalent bonds with that metal, is called a "coordination complex." it typically happens when an atom donates it's electrons to the d the empy d orbital of another atom

Root Mean Square

RMS RMS is a mathematical calculation and it can be applied to voltage, current, to sine waves, or even to other waveforms such as square waves. To find RMS, you take readings at various time intervals, square all of those readings, take the average of those squares (i.e., the mean of the squares) and then take the square root of that average. You should understand this mathematical process for the MCAT as well as the general idea behind why it is necessary. It would also be helpful to know that the rms voltage (or current) is equal to the equivalent DC voltage (or current) that would deliver the same amount of power example- 12V + 13V + 5V+ 9V = 39 V/4 = 9.75 V average

Reaction with SOCl2 and PBr3

ROH + SOCl2 -> RCl ROH + PBr3 -> RBr Common bases Et3N, or pyridine, C6H5N

Radioactive Decay & Half Life

Radioactive decay is the process by which unstable atoms change their chemical composition over time The nucleus sometimes loses or gains electrons, lose bundles of protons and neutrons called "alpha particles," or even transforms one subatomic particle into another With the different types of DECAY- THINK OF NEUTRONS AS: neutron = a proton + an electron THINK OF PROTONS AS: proton = neutron + a positron

Work: W = Fdcosθ or Favgd

Second, W = Fdcosθ or F(avg)d Any time a force is applied across a distance, work is being done Example as pushing a block across a table, a ball falling from a height h, a force (mg) has been applied, across a distance (h) Another example if a small asteroid with a velocity of v strikes the Earth's atmosphere and is gradually slowed down, a force has clearly been exerte don the asteroid by the atmosphere, converting it's KE to heat energy This equation can be used in such scenarios to calculate the average forced exerted by the asteroid, which is change in energy (work) divided by the distance over which it was applied ( F(avg)= W/d) Units are always in Joules or N*m or kg*m^2/s^2 work is positive when the force and displacement are in the same direction (pushing a barbell up) work is negative when force and displacement are in opposite directions (lowering a barbell, pull and drop) or if work is done on a system, it is positive, if it is done by the system, it is negative

Superconductor

Material that under very precise conditions is thought to exhibit zero resistance to e- flow

Insulator

Material with very, very high resistivity. Materials like glass and Teflon allow negligible current from up to extremely high voltages

Substitution of Acid Derivatives

Mechanism Notes- --- A nucleophile can be added to a carboxylic acid or acid derivative via carbonyl carbon --- Sometimes, will it result in substitution of that nucleophile for the existing substituent --- The intermediate is an oxygen anion that collapses down to reform carbonyl --- * this auses the best LG to leave --- if the attacking nuclephile is a better LG, it will result in the original acid o Ranking of acid derivative leaving groups (best to worst): -Cl > -OCOR > -OH > -OR > -NH2 --- Think of patterns of stabilization, resonance, bases, etc.

Point Charge Fields

Model of a particle that has an electric charge (energy of the point charge is infinite) Equate to "real" gravity or gravity in space A point charge field is an electric field created by a point charge. The strength of the electric field varies with the distance r from the point charge

Meso Compounds

Molecules with two or more chiral centers that contain a plane of symmetry. This symmetry cancels out their optical activity. To recognize them, look for a center of symmetry. However, not all molecules with a plane of symmetry are meso compounds. Next, check for mirror chiral centers across the plane of symmetry (NOT between two molecules; remember that a meso compound is one molecule). MESOCOMPUNDS ARE NOT DIASTEREOMERS OR ENANTIOMERS DUE TO: No. Diastereomers are PAIRS of compounds that have the same formula, the same bond-to-bond connectivity, are non-identical, and are NOT mirror images. A meso compound is a SINGLE molecule with a mirror plane. Therefore, a meso compound clearly cannot be a diastereomer (or an enantiomer) with itself. https://www.khanacademy.org/science/organic-chemistry/stereochemistry-topic/diastereomers-meso-compounds/v/meso-compounds-new-july

Structural Isomers

Same formula, different bond-to-bond connectivity (For example: 2-methylpentane and 3- methylpentane are both C6H14).

Stereoisomers

Same formula, same bond-to-bond connectivity, but different in the 3-D arrangement of their substituents there are 2 types- enantiomers and diastereomers

Fulcrums and Boards on Strings

Simple equilibrium problems 1-Set T (clockwise)= T (counterclockwise) ---Include all torques, including torque created by mass of the board ---Rotate clockwise, T is (-) ---Rotate counter clockwise, T is (+) 2-For a board with a mass, force due to the mass of the board will act at the center of the mass, which will ALWAYS be at the exact linear center of a uniform board 3-Don't forget to set TORQUES equal to each other, not FORCES Units should be N * m 4-Forces or tensions located exactly at the center of rotation do NOT create a torque due to r=0 and thus is ignored. Example is when a mass is centered over the fulcrum, gravity would create no torque

Capacitors

Store energy and charge by holding electrons on plates separated by a small distance symbol: 2 vertical lines of equal length C = Q/V PE stored by a capacitor: -U = ½QV -U = ½CV^2 -U = Q^2 /(2C) KE- U = ½CV^2 Variables that Affect Capacitance: - Increasing plate area increase capacitance due to more area to store e -Thickness has not affect, due to e- not lining up on sides or back of plate -Increasing distance between plates increases V for given Q, thus decreasing capacitance - Increasing strength of dielectric increases capacitance because it lowers the electric field between plates ( field from aligned dipoles partially cancels out main field from plates), allowing for a lower voltage for same among of charge -Increased voltage decreases capacitance

Thin-Layer CHromatography

TLC is a solid-liquid partitioning technique in which the mobile liquid phase ascends a thin layer of absorbent (generally silica, SiO2). The thin layer absorbent acts as a polar stationary phase for the sample to interact with. A very small sample is spotted near the base of the plate and via capillary action, the components of the spotted sample are partitioned between the mobile phase and the stationary phase. Rf= distance traveled by component/ distance traveled by solvent ---Given that Rf is a ratio of the distance traveled by the component over the distance traveled by the solvent. So a number close to one means that the polarity of the component is similar to that of the solvent.

The Reaction Quotient

The Equilibrium Constant can only be calculated at equilibrium. The reaction quotient Q is defined as the ratio of the concentration of the reacting species at any point of time other than the equilibrium stage. If you make the exact same calculation using concentration values taken at any point other than equilibrium the result is called the Reaction Quotient, Q. o If Q > K, the reaction will proceed to the left or reactants. o If Q < K, the reaction will proceed to the right or products. 1) Nature of reactants and products taking part in the reaction 2) Temperature 3) Stoichiometry of the equilibrium reaction

Periodic Table Trends

Size Matters, families are similar, Zeffective Size Matters refers to the trend that is depend on atomic size. Smaller atom's nuclei are closer to their valence electrons and are held more tightyl to positively charged nucleus. Greater force causes atoms to be more electronegative, having higher ionizatione nergy, greater electron affinity, and less metallic character than a larger atom. Larger atoms are better at stabilizing charges, don't form pi bonds and have d orbitals where they can house extra electrons. They won't form pi bonds because they are weak due to decrease in overlap of p orbitals Families are elements in the same column that have similar properties chemically and physically, like SiH4 is similar to CH4

Rf Value

The Rf value is equal to the distance traveled by the solute/distance traveled by the nonpolar solvent (usually hexane). The least polar compound would be expected to have the highest Rf value due to its high solubility in hexane. Rf= distance traveled by component/ distance traveled by solvent ---Given that Rf is a ratio of the distance traveled by the component over the distance traveled by the solvent. ----So a number close to one means that the polarity of the component is similar to that of the solvent.

ΔHvaporization

The amount of energy in Joules/mole required to go from liquid to gas OR the energy that must be removed to go from gas to liquid. Again, it describes both evaporation and condensation. the enthalpy change associated with the transition between liquid and gas. Solid -> Gas = Sublimation Gas -> Solid = Deposition

Voltage (current)

The amount of potential energy a system is capable of storing per unit charge- V= PE/q Or another way to think of it is that voltage is the amount of work necessary to MOVE a charge AGAINST an electric field. Moving a charge a longer distance against the field would require more work per unit charge, thus more voltage. ---V=Ed and V= Kq/r

Critical Angle

The angle of incidence that produces an angle of refraction equal to 90° For waves passing from higher index mediums into lower index mediums, the critical angle is the angle of incidence for which the angle of refraction will be 90°. If this angle is exceeded, refraction ceases and all waves are reflected back into the more dense medium—a phenomenon called "total internal reflection." Snell's Law can be used to solve for the critical angle by plugging in 90° for θ2: n1sinθ1 = n2sinθ2 → n1sinθ1 = n2sin90' → sinθ1 = n2/n1. If the two indices of refraction are known, the unknown variable, θ1, would be the critical angle.

Atomic Weight

The average mass, measured in amu, of all the isotopes of a given element as they occur naturally. Atomic weight (actually a mass; it cannot be a weight because it is not multiplied by gravity) is usually defined as the mass of one mole of any atom. however, just think of atomic weight/molar mass/molecular weight as the "g/mol" measurement given in the periodic table for individual elements, or in the case of molecular weight, the sum of those measurements for all of the atoms in a molecule. It is the number you will use to convert grams of any substance into moles

Center of Mass:

The center of mass is a weighted average of mass distribution and we calculate it through this formula: Cmass = (r1m1 + r2m2 + r3m3 . . . )/mtotal. - r is the displacement vector getween a reference point and each mass, ALWAYS CHOOSE YORU REFERENCE POINT FIRST, - if you choose the reference point of one mass, it's r will drop

Charge value

The charge can never decrease or increase by a number that is not a multiple of 1.6 x 10-19 CHARGE IS QUANTIZED AS = e- = 1.6 X 10^-19 C Example- If you have a max charge of 8.0 X 10^-19 C, how many e- do you have? (8.0 X 10^-19 C)/(1.6*10^-19)= 5 e-

Oxidation State

The charge on an element after it gains or looses a certain number of electrons via bonding. It is the apparent charge an atom takes on while in a molecule The sum of oxidation states for all of the atoms in a molecule must equal the net charge on that molecule The oxidation states in the list is highest to lowest priority Always begin with the highest atom in the list and give it priority over the other ones, assigning the charge of the other atoms as needed to match the net charge on the molecule The oxidation state of monatomic ions is always equal to the charge on the ion

Optical Power

The degree to which a lens, mirror, or other optical system converges or diverges light. It is equal to the reciprocal of the focal length of the device: P = 1/f.

Effusion (Graham's Law)

The diffusion of gas particles through a pin hole A pin hole is defined as a hole smaller than the average distance a molecule travels between collisions E1/E2=√MW2/√MW1

ΔHfusion

The enthalpy value associated with the phase change from liquid to solid. The sign changes for the reverse process (melting). the energy that must be supplied as heat at constant pressure per mole of molecules melted (solid to liquid).

ΔHcombustion

The enthalpy value for the combustion of a compound with O2 to form CO2 and water. The standard enthalpy change of combustion of a compound is the enthalpy change which occurs when one mole of the compound is burned completely in oxygen under standard conditions, and with everything in its standard state. A high heat of combustion is associated with an unstable molecule a low heat of combustion with a stable molecule.

ΔHformation

The enthalpy value for the formation of a compound from its elements in their standard states. If the number is negative, formation is an exothermic process, if it is positive, the process is endothermic.

diffraction

The tendency of light to spread out as it goes around a corner or through a slit Without diffraction, the characteristic interference patterns would not be formed When only a single slit is used, diffraction can still occur. One way of looking at this is through Huygen's Principle, which states that every point in the slit will act as a source of spherical waves. These waves interfere with each other just like the waves coming through each of the two slits in Young's experiment. However, the interference isn't as drastic as with a double-slit, and what results is a very bright central fringe and much lighter bands on either side.

Valence Shell Electron Pair Repulsion Theory:

The theory that predicts which shape molecules will take due to the repulsion of lone pairs of electrons. It is often abbreviated as VSEPR.

Snell's Law Continued

The frequency will not change as the wave moves from one medium to another. We like to think of the frequency as the permanent "identifier" of a wave. For example, you will often hear waves referred to as "a 400 Hz wave, a 200 Hz wave, etc." This makes sense because the frequency stays the same as it passes through different mediums. The wavelength, however, must change from medium to medium (assuming they have different densities) because we know that the velocity of electromagnetic waves does NOT remain constant from medium to medium—it is generally higher in less dense mediums and lower in more dense mediums. According to v = f λ if frequency remains constant and velocity changes, wavelength must change. Because velocity increases in low index mediums, wavelength must also increase in low index mediums.

Electronegativity

The greater the difference in the electronegativity of two atoms in a bond, the more polar the bond. example- Comparing electronegativity, we see that the partial positive charge on the carbon in a C=O bond is greater than the partial positive charge on the carbon in a C=N bond. This indicates that carbonyls are more reactive than comparable imines This shows us that oxygen forms stronger hydrogen bonds than does nitrogen. Polarity results in partial positive and partial negative charges, which are clues when trying to identify the nucleophile and electrophile in a reaction. To be a base or nucleophile, a molecule must have a full or partial negative charge. To act as an electrophile, it must have a full or partial positive charge.

Q5. Beakers 1 and 2 contain 0.25 L of water and 0.5 L of water, respectively. How does the heat capacity of the water in Beaker 1 compare to that of the water in Beaker 2? How do the specific heat capacities compare?

The heat capacity of Beaker 2 will be greater than that of Beaker 1 because there is more water available to absorb heat in Beaker 2. However, the specific heat capacity of water in both beakers will be identical - specific heat capacity is an intensive property.

Radicals

The heterolytic cleavage of bonds during reactions results in paired electrons on just one of the atoms. A homolytic cleavage sends ONE electron to one species and ONE to another, generating radicals. Radicals also form as a result of damage to the molecule itself. For example, radiation has sufficient energy to strip electrons off of molecules, creating radicals. That is why radiation exposure is dangerous and carcinogenic.

Impact of Salts on the Dissolution of Weak Acids and Weak Bases

The percent dissociation of benzoic acid (weak acid) decreases in a sodium benzoate solution. -In case one, sodium benzoate dissociates to release benzoate ions, which shift the acid dissociation equilibrium for benzoic acid to the left. The percent dissociation of ammonium hydroxide (weak base) decreases in an ammonium chloride solution -Similarly, ammonium chloride dissociates to release ammonium ions, which shift the base dissociation equilibrium for ammonium hydroxide to the left. SO basically, Ammonium chloride is already dissociating, thus shifting the solution to make it more basic, so ammonium hyrdoxide won't have an effect.

Period

The period is the amount of time required for one full wavelength to pass a fixed point (units = seconds) Period and frequency are always inverses of each other

Boiling Point

The temperature at which boiling occurs; the temperature at which the liquid and vapor phases of a substance are in equilibrium. the temperature at which a substance changes state from liquid to gas. Liquids boil when the vapor pressure of the liquid equals atmospheric pressure.

Ideal, Non-Viscous Flow

This is how ideal, non-viscous fluids flow. There is assumed to be no friction (drag) between the fluid and the walls of the pipe, or between fluid molecules themselves. Fluid near the wall of the pipe flows with the same velocity as fluid at the center of the pipe. This is assumed on the MCAT if they do not specify otherwise. o

Keto-Enol Tautomerization

This is the process by which an alpha hydrogen adjacent to an aldehyde or ketone becomes bonded to the carbonyl oxygen, while the double bond is switched from the carbon oxygen bond to the bond between the carbonyl carbon and the alpha carbon What you should know is that carbonyl bonds are much shorter and stronger than alkene bonds. That is the most significant difference between the two forms and is the reason the keto form is favored. The keto and enol forms are in an equilibrium with one another that strongly favors the keto form at room temperature. The keto form is more stable because the sum of its bond energies is greater than the sum of the bond energies in the enol form

Equilibrium Constant

This situation we call "equilibrium" is described mathematically by the ratio of products over reactants present at that exact point. We calculate that ratio using the law of mass action and the resulting number we call Keq. We like students to think of Keq as exactly that—a mathematical number used to define/describe/label equilibrium. This works nicely because this state of maximum "happiness" for the reaction in terms of energy and entropy is dependent on a certain ratio of reactants to products. If the amount of either of these changes, the number we calculate for Keq will also change and then we will know that we are no longer at that ideal set of conditions (In fact, the minute that number changes we don't even call it Keq anymore, we call it Q instead).

Formation of Imine

• Primary amines yield imines STEPS: 1) The amine acts as a nucleophile, attacking the electrophilic carbonyl carbon. 2) The oxygen is protonated twice, creating the good leaving group water. 3) A base abstracts a hydrogen from the nitrogen and kicks off water in an E2 mechanism. This forms either an imine or an enamine (depending on the substitution pattern of the nitrogen).

Formation of Enamine

• Secondary amines yield enamines STEPS: 1) The amine acts as a nucleophile, attacking the electrophilic carbonyl carbon. 2) The oxygen is protonated twice, creating the good leaving group water. 3) A base abstracts a hydrogen from the nitrogen and kicks off water in an E2 mechanism. This forms either an imine or an enamine (depending on the substitution pattern of the nitrogen).

Optically active vs Optically Inactive

To be optically active means that a substance does rotate planepolarized light. Optically inactive compounds do not rotate plane-polarized light.

Formation of an Alkyl Halide from an Alcohol via SN1 Reaction

Via SN1: R3COH + HCl -> R3COH2 + + Cl- -> R3C+ + H2O -> R3CCl KNOW MECHANISM o STEPS: 1) The alcohol acts as a nucleophile, attacking the electrophilic halide hydrogen and forming the good leaving group water plus a halide ion. 2) The good leaving group water spontaneously dissociates (rate-limiting step) leaving a carbocation. 3) The chlorine ion attacks the carbocation to form the product

Formation of an Alkyl Halide from an Alcohol via SN2 Reaction

Via SN2: CH3OH + HCl -> CH3OH2 + + Cl- -> CH3Cl + H2O KNOW MECHANISM o STEPS: 1) The alcohol acts as a nucleophile, attacking the electrophilic halide hydrogen and forming the good leaving group water plus a halide ion. 2) The halide ion attacks the central carbon via SN2, kicking off water. Don't be confused by the fact that SN2 reactions are usually considered "one step." In this case the protonation of the alcohol is somewhat of a "preparatory" step to transform a hydroxyl group into a good leav

Pinacol Rearrangment (Polyhydroxyl Alcohols)

Vic-diol _ hot acid-> ketone or aldehyde Vicinal- diol (OH Neighbors) + Acid ( H3O+) KNOW MECHANISM Two hydroxyl groups must be in the Vicinal position and the carbons bearing those 2 hdroxyl groups must be tri or tetra substituted by R groups. If tri-substituted, it will yield aldehyde If tetra substituted, it will yield a ketone

Mole-to-mole Conversion:

We have found that students perform much better on these problems if they have a map already in their head of where they can go. We do not want you to memorize the flowchart shown below. However, if you can internalize it naturally you will always be able to plan out exactly how to move from what you are given to what you need to calculate

Weak bases

Weak acids and bases do not dissociate readily in solution. As a general rule, an acid with a pKa greater than zero, or a Ka less than one, can be considered a weak acid. Similarly, a base with a pKb greater than zero, or a Kb less than one, can be considered a weak base. Examples of Weak Bases: Anything NOT on the strong base list. H2O, NH3, R3N, pyridine, Mg(OH)2, etc.

Entropy (∆S)

a measure of the randomness or disorder in a system. Reactions and other processes will be more likely to be spontaneous if they increase entropy. Entropy is measured by Joules/K As rxn proceeds forward, if randomness increases, energy is released and energy can do work If randomness decreases, energy is needed to increase/create order, thus that energy is unavailable to do work. positive ∆S = increased randomness, and thus more energy available to do work. -With increased randomness, the energyc an focus on doing work negative ∆S = decreased randomness, and thus less energy available to do work. -The energy is being used to create order, which requires energy, thus taking away energy to do work. Reactions at equilibrium are at maximum entropy.

Precipitate

a solid produced during a chemical reaction in a solution a solid formed inside of a solution as the result of a chemical reaction, such as the common ion effect. Precipitates only form when the ion product exceeds the solubility product constant, Ksp. For example, given the dissolution of iron(III)chloride in water- [Equation: FeCl3(s) ↔ Fe3+(aq) + 3Cl- (aq)], if NaCl is added to the solution Le Chatelier's principle predicts that the reaction will shift to the left, reforming the solid.

Non-volatile

a substance that has no measurable vapor pressure the substance does not form a vapor, or has an extremely low vapor pressure, at room temperature. This usually refers to solutes such as sodium chloride that do not contribute to the vapor pressure of a solution when dissolved in a solvent. By contrast, something like methanol would have its own vapor pressure that would add to the vapor pressure of the solvent into which it is dissolved.

Absolute Temperature

a temperature measured from absolute zero in Kelvins An absolute temperature is any temperature measured relative to absolute zero. The Kelvin scale is measured relative to absolute zero, where absolute zero is defined as 0 degrees Kelvin—therefore all Kelvin temperatures are absolute. Absolute zero is a theoretical temperature limit where all molecular motions cease ABSOLUTE TEMPERATURE= NO MOLECULE MOTION

Electron Donating and Withdrawing Groups

o To determine if a group is electron donating or withdrawing: 1) Look at the first atom from the point of attachment. Compare its electronegativity to the atoms bound to it. If it is more electronegative, it will bear a partial negative charge and if it is less electronegative, it will bear a partial positive charge. 2) Atoms with full or partial positive charges withdraw from whatever they are attached to. Atoms with full or partial negative charges donate to whatever they are attached to. 3) Hydrogen is considered neither electron donating nor withdrawing. EDG increase the ability to react, by stabilizing the carbocation, allowing for it react EWG decrease the ability to react, by destabalizing the carbocation, it is pulling the electron density away from the aromatic ring into itself, thus making it less reactive. 4) Alkenes are weakly electron withdrawing (just memorize this one)

Comparing Electric Field Equations to Gravity

g (strength of gravitational field) = E (strength of electric field) G (constant) = K (constant) h (distance) = r or d (both variables are used for distance in electric field equations) m (mass) = q (charge) F = F (used straight across) gh (gravitational potential) = V (voltage, electrical potential To derive the correct electric field equation, simply apply the conversions above to the equations you already know for gravity. Be sure to differentiate between constant electric fields and point-charge fields: ---Constant electric field equations are derived by comparison to gravity near earth ---point-charge field equations are derived by comparison to actual gravity (i.e., what gravity "really" does near earth, or gravity in space).

Half-Equivalence Point

midpoint of the nearly horizontal section of the graph At this point, pH = pKa For example- [HA] = [A-] at the half-equivalence point. HA will continue to be deprotonated until at the equivalence point the solution contains 100% A- and 0% HA. This isn't true of SB and SA titrations- this is due to both SB and SA dissociating 100%, thus only having the Equivalence point and NO half-equivalence point The analyte will ALWAYS equal the titrant at equivalence points, but the moles of OH- vs H+ WONT always be the same, UNLESS it is for a SA with SB

Addition of Amines to Carbonyls (Formation of Enamines and Imines)

o Amines add to aldehydes and ketones to form imines and enamines. o STEPS: 1) The amine acts as a nucleophile, attacking the electrophilic carbonyl carbon. 2) The oxygen is protonated twice, creating the good leaving group water. 3) A base abstracts a hydrogen from the nitrogen and kicks off water in an E2 mechanism. This forms either an imine or an enamine (depending on the substitution pattern of the nitrogen). • Primary amines yield imines • Secondary amines yield enamines • Tertiary amines do not react.

Dehydration of an Alcohol: Synthesis of an Alkene

o CH3CH2OH + H2O <-> CH3CH2OH2 + <-> CH2=CH2 KNOW MECHANISM This is an equilibrium reaction. The alkene is favored by hot, concentrated acid; the alcohol is favored by cold, dilute acid. The major product is the most substituted, most stable alkene o STEPS: 1) The alcohol is protonated by the acid 2) The "good leaving group water" leaves, forming a carbocation 3) Methyl or hydride shifts can occur, but only if it results in a more stable carbocation. 4) A water molecule abstracts a proton and the electrons collapse to quench the carbocation and form an alkene. https://www.khanacademy.org/science/organic-chemistry/alkenes-alkynes/alkene-reactions/v/addition-of-water-acid-catalyzed-mechanism

Far-Sighted

o Far-Sighted = Able to focus clearly on distant objects, but not on close objects The image is formed behind the retina. For a far-sighted person, the lens has too little focusing power (the focal length is too large). This causes the light to bend less than it should, and the image is formed farther from the lens than it should.

Zeroth Law of Thermodynamics

o If object A is in thermal equilibrium with object B, and object C is also in thermal equilibrium withobject B, then objects A and C must be in thermal equilibrium with each other. For the MCAT, Just Remember This: Everything tends to move toward thermal equilibrium with everything else. Objects with higher temperatures will always equilibrate over time with their surroundings, including other objects with which they are in contact. Finally, if two objects are in thermal equilibrium, by definition they have the same temperature. NO NET HEAT IS TRANSFERED KE = 3/2kBT

Rates of Multi-Step Reactions:

o If there is a slow step, the slow step always determines the rate. o If the slow step is first, the rate law can be written as if it were the only step. o If the slow step is second (based on a few assumptions that are beyond the MCAT) the rate law is the rate law of the slow step—which will include an intermediate as one of the reactants.

Protecting Ketones/Aldehydes from Reaction

o Ketones or aldehydes can be prevented from reaction with a nucleophile or base by conversion to an acetal or ketal (which are unreactive in all but acidic conditions). Any terminal diol with at least two carbons will work. o STEPS: 1) One end of the diol acts as the nucleophile described in steps 1-2 above. 2) The other end of the diol acts as the "second equivalent of alcohol" described in steps 3-4 above. 3) Acidic conditions will return the acetal/ketal to the original aldehyde/ketone.

Near-sighted

o Near-Sighted = Able to focus clearly on close objects, but not on distant objects The image is formed in front of the retina. For a near-sighted person, the lens has too much focusing power (the focal length is too small). This causes the light to bend more than it should, and the image is formed closer to the lens than it should.

Gravitational Potential Energy

o PE = mgh (near earth) -- Anything with mass can have gravitational potential energy. For example, fluids have mass, so they can also have potential energy. However, because they don't always move as a single unit, it is more useful to replace the mass term in the formula with density ρ (mass/volume) to give PE per unit volume of fluid: PE = ρgh

Reduction Synthesis of Amines

o Reduction of amides, imines, nitriles, and nitro groups via common reducing agents such as LiAlH4, NaBH4, and H2/catalyst with pressure. Nitro groups can be reduced to the associated primary amine via all of the above listed reducing agents. Most O-Chem books focus on nitro groups being reduced by metals in HCl (M•HCl M=Fe, Zn, Sn) Nitrile groups can be reduced to the associated primary amine via all of the above listed reducing agents. Most O-Chem books focus on nitriles being reduced by LiAlH4 Imines can be reduced to the associated primary amine via all of the above listed reducing agents. O-Chem books focus on imines being reduced by NaBH3CN or H2 and a Catalyst Amides reduce to the associated primary amine via LiAlH4 only

3 Cardinal Wave Rules

o The 3 Cardinal Wave Rules: 1) Wave speed (velocity) is determined by the medium 2) Frequency never changes when a wave moves from medium to medium 3) Wavelength does change when a wave moves from medium to medium side note: Intensity and amplitude is what reflects off when it hits a surface, it depends what kind of reflector/ surface it is as well. Intensity of sound waves decrease due to reflection of sound waves off of the glass

Aldol Condensation

o The condensation of one aldehyde or ketone with another aldehyde or ketone. o STEPS: 1) A base abstracts an alpha hydrogen, creating a carbanion. 2) The carbanion will attack any carbonyl carbon in the solution. 3) The oxygen is protonated to form an alcohol. The MCAT loves the aldol condensation! It is addressed in one way or another on almost every exam. It is our experience that students think they have aldol condensations mastered, but will still struggle to predict the product accurately under tight time restrictions. Practice these over and over until you can quickly predict the product in well under a minute.

Second Quantum Number

"ℓ" or "the azimuthal quantum number" or "the angular momentum quantum number" ℓ n-1= # of subshells Gives the subshell or orbital; has values of 0, 1, 2 or 3, and from this we know the shape: 0 = s ; 1 = p ; 2 = d ; 3 = f The shape of the orbital, ℓ can equal 0, 1, 2, -1, so when n=1, ℓ=0, this refers to s orbital that is shaped as a sphere n=2, ℓ=0,1 thus we have 2 allowed values, so when ℓ is equal to 0, we get a sphere, if ℓ=1, then we get a p orbital (dumbell)

E1 Reaction

(Elimination, Unimolecular) Rate depends on the concentration of one species only and is thus first order. 1) The dissociation of the leaving group, resulting in formation of a carbocation [slow step]. 2) The abstraction of a proton with collapse of the electrons to form a double bond (which quenches the carbocation) [fast step].

Ionization of Water:

(H3O+ is the same as H+) Kw = [H3O+][OH-] = 10^-14 pKw = pH + pOH = 14 pKa + pKb = 14 If we are at 25°C, we know that Kw will be exactly 10-14 and the concentrations of H+ ions and OH- ions will both be 10^-7M.

The Solubility Product Constant (Ksp)

(Ksp) 1) Leave out pure liquids and pure solids (this will make all Ksp equations only have a numerator - if you have something in the denominator of a Ksp equation, you've made a mistake). 2) Temperature is the only thing that changes Ksp (the MCAT does not include activity coefficients). 3) Ksp can only be observed in a saturated solution. This is because saturation is the point at which the dissolution reaction has reached equilibrium. In other words, it's just like all other equilibrium constants—you cannot measure them anywhere other than at equilibrium.

Stability of Carboxylic Acid Derivatives

- Amide > Ester > Carboxylic Acid > Anhydride > Acid Chloride

Q47. T/F? For any object floating in any liquid, the ratio of SGobject to SGliquid will exactly equal the fraction of the object submerged in the liquid.

- This statement is true. To illustrate, let's pick an example that does not involve anything with a density anywhere close to water, in order to show that the ratio of SG's does indicate the fraction submerged, even when the liquid is not water. Liquid mercury has a density of about 14 g/mL. Suppose a block of iron alloy, with a density of around 7 g/mL, were placed into a beaker of liquid mercury. The iron is half-as-dense as the liquid mercury, so it should float ½ submerged. Mercury is 14 times as dense as water, so its SG = 14. Iron is seven times as dense as water, so its SG = 7. The ratio of SG-object to SG-liquid is therefore 7/14 or 1/2.

Calorie and other values

1 kcal=1 kg water x 1'C 4.184 J/1 cal 1 Kg/1L 1 kcal/kg water x 1'C 1Kg/L = density of water Convert liters into grams using 1 Kg/L

Pressure units of pascals to mmHg to atm to Torr

1 x 10^5 Pascals = 1 atm = 760 mmHg = 760 Torr When you use any of the pressure or fluid equations below, you'll get Pascals, NOT atm, torr, or mmHg.

Bonding and Anti-Bonding Orbitals:

1) Anti-bonding orbitals are higher in energy than bonding orbitals. 2) Bonding orbitals contain electrons that are "in phase" and are said to be "attractive"; anti-bonding orbitals contain "out of phase" electrons that are said to be "repulsive." 3) Know what drawings of bonding and anti -bonding orbitals look like.

Recognizing Buffer Problems:

1) Watch for equimolar amounts. -The maximum buffering strength occurs when the [HA] is equal to the [A- ]. This is the ratio one would start with if making a buffer in the lab. Therefore, be on the lookout for equimolar amounts of a weak acid and its conjugate base, or a weak base and its conjugate acid. 2) Watch for conjugates. -To be a buffer, the two equimolar substances are often conjugates of each other, such as: NH3 and NH4, CH3COO- and CH3COOH, or HCO3 - and CO3 2-. 3) Watch for WEAK acids or bases. - The equimolar pair must be a weak base or a weak acid and its conjugate. -Strong acid or strong base conjugate pairs do NOT form buffers. 4) Watch for resistance to pH change. -Any time an acid or base is added to a solution and the pH does not change "very much," or "changes slightly," this should be a dead giveaway that the solution is a buffer. -Anytime the chart shows a near horizontal line 5) Watch for the half-equivalence point. -Remember that only solutions of weak conjugate acid/base pairs have a buffer region, and therefore they are the only solutions that have a half-equivalence point. 6) Watch for pH = pKa. - Many students memorize this principle, but fail to recognize that what it is really saying is that pH = pKa at the midpoint of the buffer region. This is another unmistakable clue that you are dealing with a buffer. -THIS IS AT THE HALF-EQUIVALENCE POINT 7) Watch for the ratio of [HA]/[A- ] or [A- ]/[HA]. -One particular problem on the CBT practice exams seems to stump the majority of students. -The question stem asks about the ratio of an acid to its conjugate base. Those who recognize it as a buffer problem usually answer it correctly. Those who do not guess. -At the half-equivalence point the concentrations of HA and A are equal. Therefore, the ratio of[A-]/[HA] must be one. When we plug this into the H-H equation we get: pH = pKa + log(1). The log of one is zero, so this term falls out, demonstrating that pH = pKa at the half equivalence point.

Entropy increases with increasing:

1) number of items/particles/etc. Caveat: The number of moles of gas trumps the number of moles of species in any other phase. Thus, even if a reaction turns two moles of reactants into one mole of product, if that one mole of product is a gas, and the reactants are not, entropy has increased; and ∆S will therefore be positive. So anytime something becomes a gas, ∆S has increased. 2) volume, more space for molecules to move 3) temperature or increase KE, 4) disorder (e.g., S is greater for an amorphous material than for a crystal) 5) complexity (e.g., S is greater for C2H6 than for CH4) -With more moles, more complexity, there is more disorder, thus higher ∆S

How is vapor pressure affected by temperature?

1)temperature- --- ↑ Temp,= ↑ Vp due to ↑ in KE, thus higher avg KE in molecules with ↑ Temp

Solving Equilibrium Problems

1-Solve all equilibrium problems by setting forces or torques equal to each other F (left)= F (right), F (up)= F (down), T (clockwise)= T (counter clock) 2-List opposing forces in 2 columns: -- right column, write down all of the forces/ equations that predict those forces which push object to the right -- Left column, write down forces that push to the left -- One force should be unknown 3-Add up each column and set sum of 2 columns equal to each other 4-Last, solve for unknown variable ---ALWAYS draw free body diagram, double check for missing forces IF AN OBJECT WITH A POINT OF ROTATION IS, stationary or exactly balance, then it must be in equilibrium, if an object is in rotational equilibrium, the net torque on the object must be zero.

Specific Heat of Water

1.0 cal/g˚C or 4.18 J/g˚C ALSO REMEMBER ROOM TEMPERATURE IS (25°C).

IR Absorbances: Nitriles

2250 cm⁻¹ sharp, deep

Second Order

1/[A] vs. time is linear with slope = k A second order reaction depends on the concentrations of one second order reactant, or two first order reactants.

Alkali Metals

1A to the far left

Overtones

1st overtone, 2nd overtone, 3rd overtone 1st overtone is NOT the same as the 1st harmonic The first harmonic is ALWAYS CALLED THE FUNDAMENTAL FREQUENCY, the 2nd harmonic is 1st overtone, and the third harmonic is the 2nd overtone and so fourth 2nd harmonic= 1st overtone 3rd harmonic= 2nd overtone 4th harmonic= 3rd overtone 5th harmonic= 4th overtone....

Protection of Alcohols

2 common examples KNOW MECHANISM TMS: ROH + TMS-> RO-Si(CH3)3 Protection by MOM: ROH + Base-> RO- + CH3OCH2Cl (MOMCl)-> ROCH2OCH3 (RO-MOM) Acidification will remove either protectiong group to restore alcohol https://www.youtube.com/watch?v=KsdZsWOsB84

IR Absorbances: Saturated Alkane

2800 cm⁻¹ sharp, deep

Alkaline Earth Metals

2A just to the right of Alkali metals

IR Absorbances: Carboxylic Acid

3000 cm⁻¹ broad, overlaps CH

sp2 hybridization

33% s / 67% p Trigonal Planar or Bent [120˚]

IR Absorbances: Amide

3300 cm⁻¹ broad, deep

IR Absorbances: Alcohol

3300 cm⁻¹ broad, separate from CH

IR Absorbances: Amine

3300 cm⁻¹ broad, shallow

Visible Light

390-700 nm ROY G BIV R-red-700 nm O-orange-650 nm Y-yellow- 600 nm G-green-550 nm B-blue- 500 nm I- Indigo- 450 nm V- Violet-380 nm Red light is lowest energy, lowest frequency and longest wavelength Violet light is the highest energy, highest frequency and shortest wavelength

Benzene

6 membered rign with alternated double and single bonds, its a conjugated pi system Ph, C6H5, Ar -A phenyl group, Ph, is attactched to a primary chain, a benzyl group has CH2 attaching the benzene to the ring, and aryl is ANY aromatic ring system -C6H5, ALWAYS a benzne, an alkane chain.

sp3 hybridization

75% p character, 25% s Tetrahedral, Trigonal Pyramidal, or Bent [109.5˚]

Double Displacement (Metathesis reaction)

A double displacement reaction, also known as a double replacement reaction or metathesis reaction, is a type of reaction that occurs when the cations and anions switch between two reactants to form new products.

Buffers

A buffer solution contains a weak acid and weak base, often the conjugates of each other and is normailly within 1 pka of the existing solution. In a buffer there is an equilibrium between a weak acid and its conjugate base, or between a weak base and its conjugate acid. The nearly horizontal area surrounding the half-equivalence point is called the "buffer region." Adding a relatively large amount of titrant at this point in the titration will have little effect on pH

Fractional Distillation

A fractionating column is placed between the heating flask and the condensing arm Mixture is heated to slightly above the boiling point of the more volatile liquid Gas rises through a column of glass beads or metal shards Causes any impurities in the vapor, molecules form the liquid iwth the higher boiling point, to condense and fall back into the flask, resulting in better separation More volatile compnent will be above it's boiling point and therefore not condense This approach allows for separation of compounds with boiling points less than 25'C apart

What two quantities are equal when a liquid boils?

A liquid boils when the vapor pressure of that liquid is equal to atmospheric pressure

Osmotic Pressure

A measure of the tendency of water to move from one solution to another across a semi-permeable membrane. Usually represented by the capital Greek letter pi, Π. It is the side that will receive the water via osmosis that has the higher osmotic pressure. In other words, more solute means more osmotic pressure. o Π = iMRT ; i = # of ions formed in solution, M is the solute molarity, R is the gas constant T is the absolute temperature.

Charge vs Time graph

A voltage vs. time graph for charging and discharging a capacitor:

Base Dissociation

A- + H2O <-> OH- + HA Kb = [OH- ][HA]/[A- ] Ka*Kb = Kw = 10^-14 (at 25°C); because ([H+][A- ]/[HA])*([OH- ][HA]/[A- ]) = [H+][OH- ] = Kw Kw = Ka*Kb that Kb and Ka are inversely related, and therefore recognize that the smaller Kb represents the stronger acid (because Ka and acid strength are directly related

Reducing Agent

An atom or molecule that donates e- to another atom or molecule and is itself oxidized in the process ELECTRON DONATOR

Magnetism

Analogous to electricity with the following changes: 1) Replace charges with North poles 2) Replace negative charges with south poles 3) Magnet fields proceed from north to south, instead from positive to negative Magnetic fields are created by changing electric fields --- Changing electric fields CREATE magnetic fields, and changing magnetic fields CREATE electric fields Magnet fields are also created by currents (moving charges) ---Any movement, velocity, rotation, etc of a charged particle causes a CHANGE in the electric field created by that charge, and thus CREATES a magnetic field ---Following have moving charges: -----Nuclei with odd atomic or mass number (nuclear spin), electrons (orbin and spin), current (moving e-), Bar magnets

Antinode

Anti nodes oscillate vertically, not horizontally nodes DO NOT oscilate

Oxidizing Agent

Atom or molecule that accepts e- and is REDUCED in the process ELECTRON ACCEPTOR

The Octet Rule

Atoms of low atomic number (<20) tend to gain or lose electrons to obtain exactly eight electrons in their valence shell. This is the highly stable "noble gas configuration." This is why sodium forms the ion Na+ and not Na2+ o EXCEPTIONS to the octet rule: 1) Hydrogen and Helium: Stable with only two electrons in their valence shells (e.g., H2) 2) Boron and Beryllium: Stable with only six electrons in their valence shells (e.g., BF3) 3) Atoms from the third period or higher can accept more than eight electrons. Common MCAT examples include: PCl5, SF6, PO4 3- and SO4 2-.

Leaving Groups

Atoms or molecules that leave parent molecule during a rxn, take both electronsform the bond with they leave best leaving groups are those that are most stable after they leave X ; -OCOR ; -H2O + ; -Tosyl ; -NH3 + ; -N2 + (diazonium)

Avogadro's number

Avogadro's number of anything. Just as a dozen is defined as 12 of anything, a mole is 6.022 x 10^23 of anything. You can have a mole of atoms, molecules, cars, monkeys, whatever

Important Terminology Regarding Covalent Bonds:

BOnd length, bond energy, bond dissociation energy, heat of combustion

Bond Length and Bond Strength

Bond Length- shortest to longest Triple bonds-> double bonds-> single bonds Stability- least to most Single->double->triple Reactivity- least to most single-> triple-> double Bond strength- Weakest to strongest single-> double-> triple

C = q/∆T

C= heat capacity q= heat or energy ∆T= Change in temperature

IR Absorbances: Carbonyl

C=O 1700 cm⁻¹ sharp, deep

Alkanes

Carbon carbon or carbon hydrogen single bonds, gasoline, tar, crude oil, butane, methane, etc Nomenclature- ane suffix Physical Properties - insoluble in water, low density, non-polar, oil or gas o Melting and Boiling Point Trends: Master the trends listed below; these general principles apply not only to alkanes, but to most other functional groups we will study. 1) Boiling point increases with increasing chain length and/or molecular weight. 2) Boiling point decreases with increased branching. 3) Melting point increases with increasing chain length or Molecular weight 4) Straight-chain alkanes have the highest melting points. Among branched alkanes, however, increased branching increases melting point. Remember, where there is increased molecular interactions, there needs to be higher melting and boiling points

Intermolecular Forces: Capillary Action

Cohesive forces: - Cohesive forces are intermolecular forces BETWEEN the molecules of a liquid, binding the molecules to one another Adhesive Forces: -intermolecular forces between the molecules of the liquid and the molecules of the container. This is well illustrated by the meniscus formed when water is in a burette. The adhesive forces are greater than the cohesive forces, and therefore the water appears to "stick" to the sides of the burette (i.e., concave-up meniscus). Water droplets on a freshly waxed car are a good example of cohesive forces exceeding adhesive forces. There are intermolecular forces between the water and the surface of the car, but the cohesive forces between water molecules are much greater, causing them to coalesce into a sphere-like droplet

Good vs. Poor Electrolytes

Covalent compounds that dissociate 100% in water, such as strong acids and strong bases, make good electrolytes. Strong Acids, strong bases Other covalent compounds are usually poor electrolytes. Ionic compounds that are soluble in water always make good electrolytes Salts

Current

Current flows OPPOSITE to the direction of electron flow I = ∆q/∆t --- Think of current as the amount of charge/ e- that flows during a point of time Current flows from + to - e- flow from - to We can determine current flow by looking at the orientation of the battery. large lines in a normal picture reps. the + termina. Remember, there is NO + chrages flowing through the wire, current is only the flow of electrons. Remember, current flow and e- flow is oppisote

Epoxdies

Cylic ethers involving one O and 2 C in a 3 membered ring Severe ring strain, thus highly reactive Acid catalyzes rxn by protonation Oxygen and makig it a better elacing group KNOW MECHANISM

Density

D = m/v -mass divided by volume Density of water: 1000 kg/m3 or 1.0 g/cm3; recall that 1 cm3 = 1 mL, 1 L of water = 1 kg, and 1 mL of water = 1 g

Epimers

Diastereomers that differ at only one chiral center. Many pairs of carboydrates are epimers (e.g., glucose and galactose).

Dalton's Law of Partial Pressure

Dalton's law states that the sum of partial pressures equals the total pressure If we add more of gas at P1 to an existing mixture of three gases, we increase the total pressure and the partial pressure of only gas 1. It has not effect on the partial pressures of the other gases. What does happen is when we add to P1 or any other parts, it doesn't decrease other partial pressures, but it does decrease the mole and mass fraction of other gases.

Dispersion

Dispersion is a change in index of refraction based on the frequency (or wavelength) of a wave. In a material with dispersion, different frequencies (or wavelengths) will be refracted to different angles, for the same incident angle. The classic example of dispersion is white light passing through a prism. For visible light traveling through glass longer wavelengths have smaller indices of refraction and therefore bend less than smaller wavelengths. This means red light bends the least, and violet light bends the most. This difference in refraction separates the white light into its colored components and produces a rainbow.

E=hf

E- Energy of a photon h= Plank's constant f=frequency v = f (lambda), f=v/lambda, which you can then plug into the energy equation for E=hv/lambda

Velocity of sound waves in a gas

Elastic property is "bulk modulus", B Inertial property is the density of the gas, ρ: ---V= sqrt (B/ρ) Bulk modulus is directly proportional to density and temperature, so as temperature increases, Velocity increases,

Velocity of a wave on string

Elastic property that provides restoring force in a string is tension The inertial property is mass per unit length, the linear mass density: μ: v = sqrt(T/μ) --- μ= linear mass density Increased tension ALWAYS increases velocity A thicker string (increased mass per length), decreases velocity, only if tension stays the same.

Titration of a SA w/ SB or SB w/ SA:

Equivalence Point/Stoichiometric Point = midpoint of the nearly vertical section of the graph. At this point [titrant] = [analyte]. For example, for a solution of NaOH being titrated with HCl, at the equivalence point [HCl] = [NaOH] in the flask. Put another way, the moles of HCl in the beaker = the moles of NaOH in the beaker. Because HCl and NaOH are both considered "strong" (i.e., dissociate 100% in water), they will both produce the same amount of ions per mole. Thus, for titrations involving a SA and a SB, [H+] = [OH- ] at the equivalence point (this is NOT true if a WA or WB is involved, as we'll discuss below). By definition, if [H+] and [OH- ] are exactly equal, pH = 7 at the equivalence point.

Oxidation of an Alcohol

FOcus on recognizing oxidizing agents themselves and general characteristics, like how secondary alcohols can only form ketones and tertiary alcohols cannot be oxidized at all. 1˚ Alcohols -> Aldehydes -> Carboxylic Acids 2˚ Alcohols -> Ketones 3˚ Alcohols cannot be oxidized further

Farad

Farad= A unit of capacitance: it is a summary unit similar to newton, it is similar saying 1 Newton instead of saying 1 Kg*m/s²: we can say 1 farad instead of saying 1 C² * s²/m²*kg A farad is the amount of capacitance necessary to hold 1 C of charge on a capacitor with a potential difference of 1 Volt

Faraday vs. Farad

Faraday= obsolete unit of charge equal to thecharge on ONE mole of electrons, so Faraday's constant= 1 faraday Farad= A unit of capacitance: it is a summary unit similar to newton, it is similar saying 1 Newton instead of saying 1 Kg*m/s²: we can say 1 farad instead of saying 1 C² * s²/m²*kg A farad is the amount of capacitance necessary to hold 1 C of charge on a capacitor with a potential difference of 1 Volt

Pulleys

Fm= mg/(# vertical ropes directly lifting mass) A vertical section of rope must lift the mas directly either by being attached to the mass or by lifting a pulley that is attached to the mass One most isolate a single segment of orpe and pull upward on that segment only, does it lift the mass? If not, it doesn't get included in the calcluation

Examples of Nomeclature

Fe2O3= Iron (II) Oxide Ammonium Nitrate- NH4NH3 MgCl2- Magnesium Chloride Sodium Bicarbonate-NaHCO3 CaCO3= Calcium Carbonate Mercury (II) Sulfide= Hg2S Good practice sites: http://www.wbu.edu/academics/schools/math_and_science/chemistry/resources/inonomen/quiz.htm http://chem.libretexts.org/Core/Inorganic_Chemistry/Chemical_Compounds/Nomenclature_of_Inorganic_Compounds

Newton's Laws

First Law- Law of Inertia Second Law- Force equals Mass times acceleration Third Law- For every action, there is an equal and opposite reaction

Sigma bonds

First bond between 2 elements is always a sigma bond (σ), it is the head to head overlap of two atomic orbitals

Standard Temperature and Pressure

For the MCAT, unless told otherwise, assume all gases are ideal and start out at STP --- At STP, the variables in the Ideal Gas Law are defined as follows: • P = 1 atm • V = 22.4 L • n = 1 mole • R = 0.0821 L*atm/mol*K or 8.31 J/mol*K • T = 273 K (0°C) STP is NOT Standard conditions: standard conditions is a set of agreed-upon conditions and are NOT interchangeable --- ex- STP is 0°C and temp in standard conditions is 25°C

Laminar Flow

Fluid flows in pipes in concentric sheets, each with different velocities. The fastest flow is at the exact center of the pipe and the slowest is at the interface with the wall of the pipe

Convection

Fluid movement caused by the hotter portions of a fluid rising and the cooler portions of a fluid sinking. Air currents and convection currents in water are examples. When temperature of wall or door from the air are in contact, convection occurs. When a material is hotter, heat rises, and the cold air goes down. cold air is more dense, falls to the bottom, hot air is less dense, thus rising.

Fluid Pressure Formula

Fluid pressure can be thought of as the average force of molecular collisions per unit area, or as the weight of the column of fluid above the point of measurement. Note that in this case h is depth, NOT height Pascal's Law: Pressure is transmitted in all directions, undiminished, through a contained, incompressible fluid. Put another way, if pressure increases at any point in a confined, incompressible fluid, it increases by that same amount at every other point within that fluid. Pressure is a constant for any vertical depth within the same fluid; even if a convoluted pipe leads to that depth; even if the surface of the fluid is not directly above the point of measurement; and whether the container is 5 mm or 5 miles wide. In other words, if a pipe exits horizontally from an enormous 1,000-meter-tall water storage tank, the fluid pressure inside that pipe is the same as the fluid pressure inside the tank at that same vertical distance below the surface of the fluid.

Levers

Fm-mg(L1/L2) - L1 and L2 refer to lever arms for mass and applied force respectively

Ramps

Fm= mg(h/d) h- height of ramp d- distance along hypotenuse Fm= Force necessary to do work with machine, which is less when doing it without a machine ---WORK WITH OR WITHOUT THE MACHINE WILL ALWAYS BE THE SAME

Collisions cause Reactions to Occur

For a reaction to occur: 1) The reactants must collide with enough energy to overcome the energy of activation 2) The reactants must be in the correct spatial orientation o Rate is measured as the change in molarity (M) of the reactants per second (M/s) How does the following affect reaction rate: Reactants- Increases rxn rate as long as reactants are in rate law Products- no effect Catalysts- Increase rate Energy of Activation- decreases reactions at constant temp. Energy of Transition State-decreases reactions at constant temp Energy of the reactants- Closer to Ea, thus increasing rxn rate Temperature-Increase KE, thus increasing rxn rate

Wavelength

For a simple sinusoidal wave, the wavelength (units = meters) is the distance between two adjacent crests (a.k.a., peaks, maxima), or between two adjacent troughs (a.k.a., valleys, minima). For a more complex wave, the wavelength is the distance between points where the wave begins to repeat itself. For example, the wave used to represent heart rhythm has multiple peaks per cycle, so the distance between peaks would NOT be the wavelength.

F = mgsinθ

Force down an inclined plane, parallel to the surface

Work

Force times Displacement

Fourth Quantum Number

Fourth Quantum Number: a.k.a. "ms" or "the electron spin quantum number" Gives the spin, which is either +½ or -½. Positive spin is represented by an up arrow in an electron configuration diagram and negative spin is represented by a down arrow. Electrons can "spin" two possible ways, thus two possible values So there is ms= +½, which is spin up and ms=-½, which is spin down.

Freezing Point Depression:

Freezing point of a liquid depressed when a non-volatile solute is added according to: ∆T = kfmi ; where kf is a new constant, different than kb above. --∆T = kbmi ; - kf is a constant - m is molality (NOT molarity) - i is the number of ions formed per molecule one can think of freezing point depression and boiling point elevation as being a function of not just moles of solute, but moles of solute particles

Saponification (Hydrolysis of an Ester)

Hydrolysis of an ester to yield an alcohol and the salt of a carboxylic acid. o STEPS: 1) The hydroxide ion (NaOH or KOH) attacks the carbonyl carbon and pushes the C=O electrons uponto the oxygen. 2) The electrons collapse back down and kick off the -OR group. 3) Either the -OR group, or hydroxide ion, abstracts the carboxylic acid hydrogen, yielding a carboxylate ion. This associates with the Na+ or K+ in the solution to form "soap."

Ion's in SOlution

Hydroxide, nitrate, nitrite, chlorate, chlorite, hypochlorite, perchlorate, carbonate, bicarbonate, ammonium, sulfate, phosphate, manganite, permanganate, and cyanide. OH⁻, NO₃⁻, NO₂⁻, ClO₃⁻², ClO⁻, ClO₄⁻, CO₃⁻², HCO₃⁻, NH₄⁺, SO₄⁻², PO₄⁻³, MnO, MnO₄⁻, CN⁻

Sulfuric Acid

H₂SO₄

Phosphoric Acid

H₃PO₄

Steric Hindrance

If more than one mechanism, intermediate, electrophile or nucleophile is possible The one that invloves least steric hindrance will be favored

Kinetic Friction vs Static Friction

If there's sliding, it's kinetic friction; if there's no sliding, it's static friction. Static Friction Examples: You try to push a parked car down the street but cannot because the static friction is too much. A block sitting on an inclined table does not move because the static friction holds it in place. You push a couch across your living room. Your slippers provide the static friction required for you to grip the floor. Kinetic Friction Examples: Rubbing both hands together to create heat. A sled sliding across snow or ice. Skis sliding against snow. A person sliding down a slide Static friction is typically stronger than kinetic friction. Static friction coefficient is .60 and for kinetic it is .55. Force of friction lessens when you overcome static friction.

Resonance

Important Clarifications: o Resonance structures are a "snapshot" of the different arrangements of electrons that contribute to the "actual structure." o The actual structure is a weighted average (i.e., hybrid) of all of the contributors and does NOT look exactly like any of the individual resonance structures. o Individual resonance structures contribute differently; the most stable structures contribute the most to the actual structure and the least stable structures contribute the least. o The actual structure does NOT resonate back and forth between forms; it is a permanent weighted hybrid of the contributing structures.

Reading C¹³-NMR Spectra

Important difference from H-NMR: -- No spin-spin splittings (all peaks are singlets) -- No integration (area under curve is not relative to number of carbons) Absorbance range: - 0 - 220 ppm -- 220 ppm is downfield- deshielded -- 0 ppm is upfield= sheilded -- use Tetramethyl silane is defined as 0 ppm Similar to IR C13 absorbances to know: C-C = 0-50 ppm C-O = 50-100 ppm C=C = 100-150 ppm C=O = 150-200 pm Focus more on H-NMR

Index of Refraction:

Index of Refraction: n=c/v The index of refraction is a relative comparison of the speed of light in a vacuum (c) to the speed of light in that medium (v): n = c/v. Therefore, in order to get a value less than one, the speed of light in that medium would have to be greater than the speed of light in a vacuum which is only possible for circumstances beyond what the MCAT would be testing on. A value of 1.5 for n simply tells us that the medium has some density, and is more dense than air, which has a value for n that is very close to one.

Spectator Ions

Ions that may be dissolved into a solution but have no effect on the equilibrium. Addition of a common ion will cause precipitation. If a spectator ion is added no precipitation will result.

Diffusion (Graham's Law)

It is the process by which gas molecules spread from areas of high concentration to areas of low concentration due to random motion imparted to them as a result of their kinetic energy and collisions with other molecules E1/E2=√MW2/√MW1

Electromagnetic Spectrum

Know the order and relative energy of each class of electromagnetic radiation All of the following waves are light: -micro waves, radio waves, etc, NOT JUST VISIBLE LIGHT In terms of frequency- -- gamma rays > x-rays > ultraviolet > visible light > infrared > microwaves > radio waves. Long wavelength= lower frequency- less energy Shorter wavelength= higher frequency= more energy All of the waves on the electromagnetic spectrum travel at the same speed in a vacuum, the speed of light. use: c = 3.0 x 10^8 m/s

Equipotential Lines

Lines drawn perpendicular to field lines and represent areas of equal voltage or electrical potential Equipotential lines will form concentric circles around a point charge, but not around a dipole, or in a constant electric field such as is found between the plates of a capacitor

Volatile

Liquids that evaporate quickly a term used to describe the relative tendency of a substance to form a vapor. How readily a substance vaporizes is primarily a function of its vapor pressure. Therefore, if one substance is said to be "more volatile" than another, this indicates that the former has a higher vapor pressure than the later at the same temperature

Mechanical Energy

ME = KE + PE In the absence of non-conservative forces such as friction, drag, air resistance, etc, MECHANICAL ENERGY IS ALWAYS CONSERVED ( total energy)

Conduction

Molecular collisions carry heat along a conduit, only with solids Recall that temperature is a reflection of the average kinetic energy of the molecules. High energy molecules collide with their neighbors, which in turn collide with their neighbors until eventually the energy is spread equally throughout KE is spread through higher temp. or Energy of molecules increase with higher Temp. Heat conduction is roughly analogous to current flow through a wire Conduction heat transfer occurs when there is two materials with different temperatures in contact with each other. Heat from high temp to low temp side. With

Anomers

Molecules that differ only in their spatial orientation at the anomeric carbon of a ring structure. If the anomeric OH/OR group and the CH2OH group are on the same side of the ring = Beta, if they are on the opposite side = Alpha.

Moles of Oxygen Needed for COmbustion

Moles of Oxygen Needed for Combustion: You will occasionally be asked to predict the species that will require the most oxygen to combust. Here is a simple ranking system to make such predictions quickly: Add 1.0 for each carbon and subtract 0.5 for each oxygen. The higher the resulting number the more oxygen necessary for full combustion. This is NOT, however, the actual number of moles required—this is only a ranking system. The only way to determine the exact moles of oxygen required for a combustion reaction is to write out and balance the combustion equation.

Electrical Potentials (E°)

Moving electrons can transfer energy E° show how much a species wants e-'s or wants to be REDUCED, aka gain e- These following potentials are given in volts and will ALWAYS BE PRESENTED IN WHAT IS CALLED A HALF REACTION ---Half Reaction The only half-rxns you will likely to are the following in the picture, that an aqueous metal is being reduced to form the associated solid metal. These are the most common ones that do not begin with metal cations: O₂, H₂O, H⁺

Ammonia

NH3

Ammonium

NH4+

Nitrate

NO3-

FN = mgcosθ (FN is referring to normal force)

Normal Force on an inclined plane

Nucleophiles

Nucleophiles attack carbons or other central atoms electron dense have have a full or partial negative charge Reacts fastest with available electrophile and is a function of kinetics, how fast this is going to happen, just that they are good at reacting Nucleophilicity is how easily/readily a molecule react, but NOTHING about how stable the new bond will be. Electron rich will be strong nucleophiles and react fastest. ITS ALL ABOUT THE NEED FOR SPEED NOT GOOD in protic solvents, better in Aprotic solvents. The protons in a polar solvent makes it hard for a nucleophile to attack. NH3 ; RC=CR ; H2O ; RMgBr ; X- ; RCO2 - ; CN-

Common Oxidizing Agents

O3, C32O7, CrO4, KMnO4, JOnes, COllins, PCC, PDC

Electrical Power

P=IV P=I²R P=V²/R ONLY MEMORIZE P=IV, use V=IR for missing variable and plug it in to get the other 2 P=IV and V=IR

C=Q/V

PE stored by a capacitor: -U = ½QV -U = ½CV^2 -U = Q^2 /(2C) KE- U = ½CV^2 Know how to derive it all from each other

Polar Protic Solvents

Polar protic solvents are capable of intermolecular hydrogen binding Polar protic solvents solvate both cations and anions well cationsare solvated by ion-dipole interactions anions are solvated by hydrogen bonding Affects nucleophlicity: - In polar protic solvents, nucleophilicty increases down a column of the periodic tabnle as the size of the anion increases. this is oppisote to bascicity Down a column of the periodic table -> Nucleophilicity increases Up a column of the periodic table -> Bascity increases

Phosphate

PO4^3-

Pressure Volume Graph

PV Work = P∆V (requires constant pressure, any change in volume tells you there is pv work) On a pressure vs. volume graph, the area under the curve is pv work.

Calculating Percent Mass:

Percent Mass = (mass of one element/total mass of the compound)(100%) Q20. What is the percent mass of carbon in glucose? What is the percent mass of hydrogen in water? The total MW of glucose is 180g. The weight of the six carbon atoms in glucose is 72g. Therefore, 72/180*100 = 40%. The total mass of water is 18g. The mass of the two hydrogen atoms is 2g. Therefore, 2/18*100 = 11%.

Pascal's Law

Pressure is transmitted in all directions, undiminished, through a contained, incompressible fluid. Put another way, if pressure increases at any point in a confined, incompressible fluid, it increases by that same amount at every other point within that fluid Any external pressure put on the liquid, that pressure is distributed throughout the fluid equally, so pressure in equals force out. Pressure is a constant for any vertical depth within the same fluid

Hofmann Degradation

Primary Amides (amides with only H on the nitrogen) react in strong, basic solutions of Cl2 or Br2 to form primary amines MEchanism uses decarboxlyation, thus shortening the length of the carbon chain This rxn allows you to add an amine to a tertiary carbon

First Quantum Number

Principle Quantum Number n It gives the shell, valence e= are in outermost shell, and represents the relative energy of electrons in that shell Tells us the main energy level or the type of shell it is in As n increases, a higher energy level is associated it, example n=2 > n=1

Third Law of Thermodynamics

Pure crystalline substances at absolute zero have an entropy of zero. The crystal must be perfect, or else there will be some inherent disorder. It also must be at 0 K; otherwise there will be thermal motion within the crystal, which leads to disorder." the entropy of a perfect crystal approaches zero as its temperature approaches absolute zero.

R = ρL/A

R= Resistance ρ = resistivity L = length A = cross-sectional area example- when maximizing safety and energy efficiency, long wires increase resistance and smaller diameters increase resistance as well, If it is short wires, R decreases, and if it is a big diameter, resistance decreases as well due to inverse relationship, thus with decreases resistance, it is more energy efficient and safer.

Transesterification

Reaction of existing ester with an Alcohol, creating a dfiferetn ester Uses Acid catalysis RCOORa + RbOH →RCOORb + RaOH

Oxidation Reduction Reactions

Redox rxns Any reaction where one or more e- are transferred from one atom to another The atom that LOSES e- is OXIDIZED and the atom that GAINS e- is REDUCED Example: Fe(s) + H₂O(l) -> H₂ (g) + FeO (s) --- Fe loses 2 e- and 2 H gain e-, Iron is thus the reducing agent and water is the oxidizing agent

Alkynes

SImilar to alkenes in how they react, has triple bond

Sulfate

SO4^2-

Sound Production

Sound is ALWAYS created by a vibrating medium Vibrations propagate through liquids or solids, generating pressure waves that propagate through gases like air The molecules only get displaced for a short distance near their original origin; they then quickly run into other molecules, causing them to bounce back to their original positions and the other molecules to continue forward. Molecules pushes outward from the source collide with neighboring molecules, pushing those molecules forward as the original molecules bounce back toward the source. As a mechanical wave, sound CANNOT propagate in a vacuum.

Torque and Lever Arms

T = Fℓ or T = Frsinθ or (for gravity) T = mgℓ --- Use when the force applied is NOT perpendicular to r --- Most fulcrum and board-string problems, forces act at a 90', thus sin(90')= 1 then T=Fr or Fℓ ℓ = lever arm and r = distance between the force and the point of rotation; rsinθ always = ℓ, but r = ℓ only when θ = 90' In most cases, you can simply use T = Fℓ

Work: W = ∆Energy

THINK OF WORK IN EXACTLY THIS WAY AND IN THIS EXACT ORDER First as W = ∆Energy If energy changes, then there is work ALWAYS Think work in the following situation ALWAYS: 1) Change in velocity (change in KE = work; this is the most common example) 2) Change in height (change in gravitational PE = work) 3) Change in position of masses/planets/etc. in space (change in gravitational PE = work) 4) Change in position of a charge (change in electrical PE = work) 5) Compression of a spring (change in elastic PE = work) 6) Friction (change in internal energy = work) 7) Air Resistance (change in internal energy = work)

Group/family

THe Vertical column

To calculate the "order" of each reactant using experimental data:

The "overall order" of a reaction = the sum of the exponents in the rate law

Salt of Weak Acid

The "salt of a weak acid" refers to the conjugate base of that weak acid combined with a cation to form a salt Conjugate base + cation for weak acids HCO3- = "weak acid"; CO3^2- = "conjugate base"; Na2CO3 = "salt of a weak acid" Na2+ is the cation forming the salt with the conjugate base When the salts of weak acids or weak bases dissolve in water one of the ions will undergo hydrolysis to re-form the weak acid or the weak base: 1) Na2CO3 <-> 2Na+ + CO3^2- 2) CO3^2- + H2O <-> HCO3- + OH-

Period

The HOrizontal row

Formal Charge

The difference between the # of electrons in an atom's valence shell when it is in its ground/elemental state and the number assigned (lone-pair electrons and 1/2 of the bonding electrons) to it in a molecule. Molecules prefer to get as close to 0 as possible Formal Charge = valence - assigned "Valence" meaning the number of electrons normally found in the valence shell of that atom [which can be inferred from the Group #: Group VI has six valence electrons, Group VII has seven, Group IV has four, etc.] and "assigned" meaning the number of electrons currently surrounding that atom in the given structure. NOTE: For a covalent bond involving two electrons, only one of those electrons is considered to be "assigned to" each atom. For lone pairs, both electrons are "assigned" to the atom they surround. For a radical with a single lone electron that one electron would be considered "assigned to" the atom it surrounds

Q12. Draw all possible resonance structures for a) an amide (R-CONH2) and b) the phosphate ion (PO43-). In each case rank each structure in terms of its contribution to the actual structure.

The possible resonance structures are drawn below. For the amide, the most stable structure is the one to the far left because there is no separation of charge. Next in line is the middle structure because it places a positive formal charge on carbon, whereas the structure to the right places that charge on nitrogen. Among the phosphate structures, the least stable will be the structure with a positive formal charge on the phosphorous because this has more formal charges and is the only one with both negative and positive formal charges. The other four structures will be equal contributors.

Pi bonds

The second and third bonds are always pi (π) bonds and involve side-to-side overlap of two p orbitals. Because pi bonds require side-to-side overlap, the atoms must be fairly close to one another As the radius of either atom increases, the p orbitals are spread apart, resulting in less overlap and a weaker pi bond. Pi bonds themselves are weaker associations than are sigma bonds

Molecular Weight

The sum of an atomic weight of a molecule's component atoms

Solving Half-Life Problems

There are three variables involved in half-life problems: half-life, t1/2, time elapsed, t, and the amount of the substance in grams, g. You are usually given two of those three and asked to solve for the third. Try to do this conceptually in your head—do not use a formula. For example, one question may tell you that we currently have 500 g of element Z, and that the half-life of element Z is 10 years. It then asks how much of element Z will remain 40 years from now. The half-life tells us that every 10 years the substance is cut in half. Thus, in 40 years it will be cut in half four times. Write 500 g on your scratch paper, then cut it in half four times to get the correct answer: 31.25 g. Another question may give you the initial and final mass of the substance plus the amount of time elapsed, and ask you to calculate the half-life. In such a case: -first decide how many times the substance had to be cut in half to go from the initial value to the final value (i.e., the number of half-lives). - Divide the total time elapsed by the number of half-lives to get the length of each half-life Always take notes when counting half-lives. Many students make silly errors because they miscalculate the number of half-lives. Write it down and you won't mess up! This is yet another application of the Altius mantra: Write it Down and Draw it Out!

I = ∆q/∆t

Think of current as the amount of charge/ e- that flows during a point of time always conceptualize current flow vs electron flow

Poiseuille Flow

This is how real, viscous fluids flow in pipes. Real fluids exhibit laminar flow (defined below) and have a leading edge that is parabolic in shape.

Formation of Tosylates/ Mesylates

Tosyl-Cl + ROH -> Tosyl-OR + HCl KNOW MECHANISM 1) The alcohol attacks the tosyl or mesyl halide via SN2, kicking off a halide ion. 2) A hydrogen is abstracted by the halide ion, quenching the charge on the oxygen Mesylates and Tosylates are desirable because they make very good leaving groups that will react readily with almost any nucleophile https://www.khanacademy.org/science/organic-chemistry/alcohols-ethers-epoxides-sulfides/reactions-alcohols-tutorial/v/preparation-of-mesylates-and-tosylates

Transverse vs. Longitudinal

Transverse waves cause disturbances perpendicular to their direction of travel (e.g., electromagnetic waves, a wave on a string); Longitudinal waves cause disturbances parallel to their direction of travel (e.g., sound waves, p-wave earthquakes)

sp3d hybridization

Trigonal Bipyramidal, Seesaw, T-Shaped, or Linear [90˚/120˚ or 180˚]

Q26. How many equivalents of base can be neutralized by one equivalent of H2SO4?

Two equivalents of base can be neutralized by one equivalent of H2SO4 because each sulfuric acid produces two equivalents of hydrogen ions in solution. Look to the H+ ratio to the base ratio, so 2:2

Conservation of Charge

Universe always has a 0 net charge. Charge is created by separation. If you separate one e- from a neutral atom, you create one independent unit of (-) charge, the e-. You have also created an independent unit of (+) charge, the cation

Voltage

Voltage= PE/ q (charge) or m (mass) --- V= PE/q Voltage= an entity you can multiply by mass or charge to get PE ---gh*m=mgh=PE (gravitational) --- Ed*q= PE (electrical)= V*q

V=PE/q V=Ed V=Kq/r

Voltage= potential energy per charge Voltage- moving a charge against the electric field

Hydration

Water molecules attached to ionic units in a solid

Wave Velocity in Various Mediums

Wave speed is typically equal to the square root of an elastic property of the medium divided by inertial property: v=sqrt(elastic/inertial) The elastic property is often called a modulus, the inertial property is a type of density THE MEDIUM ALWAYS DETERMINES THE VELOCITY

Weak Acids

Weak acids and bases do not dissociate readily in solution. As a general rule, an acid with a pKa greater than zero, or a Ka less than one, can be considered a weak acid. Similarly, a base with a pKb greater than zero, or a Kb less than one, can be considered a weak base. Examples of Weak Acids: Anything NOT on the strong acid list. - H2O, H2S, NH4+, HF, HCN, H2CO3, H3PO4, acetic acid, benzoic acid, etc.

ΔHvaporization

When a liquid vaporizes, the liquid must absorb heat from it's surroundings to replace energy taken by the vaporizing molecule-s in order for the temperature to remain constant. This heat required to vaporize the liquid is called the enthalpy of vaporization. The enthalpy value associated with the phase change from liquid to gas. The reverse process (condensation) simply interchanges products and reactants and thus the sign is just changed.

Total Internal Reflection

When light crosses a boundary from a slower medium (bigger n) to a faster medium (smaller n), if the angle of refraction is 90' or more, the incident light does not enter the second medium at all-100% is reflected off the boundary and back into the first medium For the Internal reflection to occur, the light MUST pass from a higher- index medium to a lower index medium, big n to small n, not small n to big n.

Solving circuits using Ohm's Law: Fourth

When you have a simplified circuit you can use Ohm's Law (V = IR) to solve for any of the three variables.

The Atom

Z= Atomic number, the number of protons, this is what defines an element A= mass number, which is protons + neutrons

Aqueous

any solution for which water is the solvent.

Anyhydrous

a compound that can form complexes with water to differentiate molecules that do not contain water from those that do A compound with all water removed, especially water of hydration. For example, strongly heating copper(II) sulfate pentahydrate (CuSO. 5H2O) produces anhydrous copper(II) sulfate (CuSO4).

Combustion of an Alkane

a radical, exothermic chain reaction with oxygen; high energy of activation. CH4 + 2O2 -> CO2 + 2H2O + Heat From highest to lowest, heat of combustion is as follows: cyclopropane, cyclobutane, cyclooctane, cyclohexane. Cyclooctane comes before cyclohexane because 8-membered rings are slightly more strained than 6-membered rings. Rings near 10-12 members or above will have ring strain equal to that of cyclohexane. Where there is more strain, there is higher combustion

Decomposition Reaction

a reaction in which a single compound breaks down to form two or more simpler substances

Single Displacement Reaction

a type of oxidation-reduction chemical reaction when an element or ion moves out of one compound and into another-that is, one element is replaced by another in a compound.

Actinides

actinides are the lower row in f- block

Diverging Lens

concave, negative always produces a negative, virtual, upright image.

f-block

d the f-block is the lanthanides and actinides which actually occur in order between the s-block and d-block elements on rows 6 and 7 respectively.

Vectors

direction and magnitude

Bond Length

distance between the nuclei of the atoms forming the bond the shorter the bondlength, the higher the bond energy, more stability, thus more energy

Electron Affinity

electron affinity is the ability of an atom to accept an electron Electron affinity generally decreases down a group of elements because each atom is larger than the atom above it With a larger distance between the negatively-charged electron and the positively-charged nucleus, the force of attraction is relatively weaker. Therefore, electron affinity decreases. Moving from left to right across a period, atoms become smaller as the forces of attraction become stronger. This causes the electron to move closer to the nucleus, thus increasing the electron affinity from left to right across a period.

∆G = ∆H - T∆S

enthalpy is basically the change in bond energy from reactants to products. If there were no change in randomness during the reaction, the amount of energy available to do work (ΔG) would be exactly equal to enthalpy (∆H). As described above, if randomness increases (positive ΔS), energy will be released and that energy (in addition to ΔH) will also be available to do work (creating a larger, more negative ΔG). if randomness decreases, energy will be "used" to create this order, decreasing the amount of energy available to do work The "T" term in the equation converts entropy into joules (J/K*K = J). You may recall that energy can also be used to increase temperature or to expand the volume (PV work), but neither occurs here because the system is both isothermal and isobaric.

Equivalence Point vs. End Point

equivalence point is where [titrant] = [analyte] -(that doesn't necessarily mean though that moles are equal to each other, especially with WB with SA or WA with SB The end point is simply the point when the indicator causes the color change. There is no causal relationship whatsoever between the solution reaching the equivalence point and the indicator changing color

The Beat Frequency

fbeat = /f1 - f2/ Occurs when 2 waves with close to the same frequency interfere When two sound waves of different frequency approach your ear, the alternating constructive and destructive interference causes the sound to be alternatively soft and loud - a phenomenon which is called "beating" or producing beats. The beat frequency is equal to the absolute value of the difference in frequency of the two waves. Picture: Demonstrate a beat and the beat frequency by drawing a long series of evenly-spaced vertical lines representing a longitudinal sound wave. Return to the first line in your series. Beginning directly on top of that first line, draw a second series of evenly-spaced vertical lines, this time decreasing the space between lines by approximately 1/3. What happens periodically? when the second sound wave has a wavelength that is 1/3 less than the first sound wave, approximately every 3rd wavefront results in an increased amplitude- a beat. This pattern predicts that if the second wave was 1/2 the wavelength there would be a beat at every other wavefront, if the second wave was 1/5 the wavelength there would be a beat every 5th wavefront, and so on.

f= (1/2)r (mirrors only)

focal point for mirrors

Velocity

how fast the wave moves in space in m/s. It is given by v = fλ

Bond Dissociation Energy

it is the same as bond energy, the amount of energy required to break or "dissociate" the bond.

Scalars

just magnitidue

First Order

ln[A] vs. time is linear with slope =-k A first order reaction depends on the concentration of only one reactant (a unimolecular reaction). Other reactants can be present, but each will be zero order. The rate law for a reaction that is first order with respect to a reactant A. It is only linear if it is the ONLY REACTANT or IF ONLY ONE REACTANT MATTERS. If it is non linear, it means it isn't first order

Center of Gravity

located exactly at the center of mass

Center of Buoyancy

located exactly at the center of mass of the fluid displaced by the submerged object (NOT at the center of mass of the submerged object itself).

Non Ideal Reflector

loss of energy and intensity as it bounces off cardinal rules still apply

M= m1m2

magnification

Gabriel Synthesis

making primary amines through Sn2 rxn of phthalimide with an alkyl halide followed by cleavage w hydrazine (NH₂NH₂) Formation of a primary amine from a primary alkyl halide; avoids the side products of alkyl amine synthesis.

mass percent

mass solute/total mass of solution * 100

ppm

mass solute/total mass solution * 10⁶ (for ppb multiply by 10⁹) Parts per million (ppm) is NOT a measure of how many solute particles there are per 1 million total particles. Although that is how most students erroneously think of it. It is nothing more than mass percent multiplied by 10^4, or "mass fraction" multiplied by 10^6. The purpose of multiplying by 1 million is to make very, very small concentrations easier to work with. ppm = mg/Kg = mg/L (since 1 L of water has a mass of 1 Kg)

Conductor

material that allows flow of electrons through it relatively unimpeded Even the best conductors exhibit some small degree of resistance to the flow of e- and even resistors do conduct e- to some small degree A material that allows electric charges to flow

molality

moles solute/Kg solvent Molarity (M) changes w/ temperature, but molality (m) does not.

molarity

moles solute/Liter solution Molarity (M) changes w/ temperature, but molality (m) does not.

mole fraction

moles solute/total moles solution (solute + solvent)

Ideal Reflector

no loss of energy or intensity to the wave as it bounces off the reflector also cardinal rules apply

Noble Gases

noble gases are the group 8A elements on the far right of the table

Inclined Planes

o F = mgsinθ ; Force down an inclined plane, parallel to the surface o FN = mgcosθ ; Normal Force on an inclined plane o Vf = √(2gh) ; Velocity of a particle at the base of an inclined plane Remember how this related to F=ma. Once you find the force, you can find the acceleration using newton's first law

Phase Diagram

o Lines on a phase diagram represent points where the two phases on either side of the line are in equilibrium. At the triple point all three phases are in equilibrium. Beyond the critical point, there is no distinction between liquid and gas and the phase is called a fluid.

pH = -log[H+]

pH of pure H2O at 25°C = 7.0, and the [H+] = [OH-]; pH > 7 = basic, and the [H+] < [OH-]; pH < 7 = acidic, and the [H+] > [OH-]; pH = 7 is defined as "neutral" and the [H+] = [OH-]

pH = pKa + log[A-]/[HA]

or pH = pKa - log[HA]/[A-] At the half-equivalence point the concentrations of HA and Aare equal. Therefore, the ratio of [A-]/[HA] must be one. When we plug this into the H-H equation we get: pH = pKa + log(1). The log of one is zero, so this term falls out, demonstrating that pH = pKa at the half-equivalence point.

P= P1 + P2

power

Pitch

rELATED TO FREQUENCY BUT NOT IDENTICAL higher pitched sounds have higher frequencies, and lower pitch sounds have lower frequencies Infrasound vs ultrasound: --- Infra sound is sound of a frequency too low to be perceived by the human ear --- Ultrasound is sound of a frequency too high to be perceived by human ear example, dogs perceive ultrasonic sounds, humans can't. Elephants perceive infrasonic sounds, humans cannot.

Super-saturated Solution

solutions usually form only when a solution is held at a higher temperature during dissolution (at which Ksp would be larger) and then slowly cooled to a temperature at which Ksp is smaller.

Standing Waves

special case of simultaneous constructive and destructive interference between two waves with identical frequencies, moving through same medium, but opposite directions At points of maximum destructive interference, the waves cancel entirely, forming a node At points of maximum constructive interference, waves add completely to form an antinode, resulting inf a waveform in which areas between the nodes appear to oscillate up and down form a crest to a trough Standing wave exhibits no NET TRANSPORT OF ENERGY AND DOES NOT ITSELF PROPOGATE: No translational Movement of Nodes or antinodes

Force (gravity)

• For gravity near earth: F = mg --For constant E-field: F = qE • For real gravity: F = Gmm/r2 --- For point charge E-field: F = Kqq/r2 (Coulomb's Law)

Diastereomers

stereoisomers that are not mirror images Two molecules with the same formula and the same bond-to-bond connectivity that are non-identical, but are NOT mirror images. There are three kinds of diastereomers you must be familiar with for the MCAT: geometric isomers, epimers and anomers. Oppisote configurations at chiral centers https://www.khanacademy.org/science/organic-chemistry/stereochemistry-topic/diastereomers-meso-compounds/v/enantiomers-and-diastereomers

Amphoteric

substances can act as either an acid or a base (e.g., H2O).

Super critical Fluid

super-critical fluid cannot be compressed back into the liquid phase by increasing pressure, nor can it be turned into a gas by increasing temperature

Acid/Conjugate Acid and Base/Conjugate Base

the "conjugate base" of an acid is the acid minus its hydrogen (e.g., HCl = acid; Cl- = conjugate base). The "conjugate acid" of a base is the base plus a hydrogen (e.g., NH3 = base; NH4 + = conjugate acid). Which species you call the acid/base or the conjugate acid/base is arbitrary you could call HCl the acid and Cl- the conjugate base or call Cl the base and HCl the conjugate acid).

Amplitude

the "distance" between the equilibrium point and a crest, or between the equilibrium point and a trough. (Distance is in quotes because the units of amplitude are not necessarily meters. They would be, for a wave on a rope, but not, for example, for a voltage wave or the electric field component of a light wave. Those would have units of volts or volts/m, respectively.) It is NOT the total distance between crest and trough! That would be twice the amplitude. Amplitude is the distance the wave rises above OR below the middle of the waveform. It is NOT the total distance from the bottom of a valley to the top of a crest (it would be half that). This makes A the correct answer.

p-block

the p-block is the set of six columns starting with boron and ending with neon

Pauli Exclusion Principle

the Pauli Exclusion Principles states that no two electrons can have the exact same four quantum numbers (i.e. occupy the exact same quantum state.) They can have up to three identical numbers, but then they must have opposite spins of +1/2 and -1/2.

d-block

the d-block is the entire set of transition metals in the middle of the table

Observed Rotation

the degree to which a sample rotates plane polarized light. However, that rotation is not a universal constant for a particular molecule. Rather, it varies depending on concentration, length of the tube, etc

Photoelectric Effect

the ejection of electrons by certain metals when they absorb light with a frequency above a threshold frequency The photoelectric effect is the observation that electrons are ejected from a material when light of sufficiently high frequency is used—but not until a threshold frequency is reached. Einstein first published an explanation for these observations in the context of the particle nature of light. If light were purely a conventional wave, increasing the amplitude sufficiently high would always result in ejection of an electron—which is not seen. Instead, we observe that the energy of each individual photon (set by its frequency) must itself be high enough for an electron to be ejected. There is a one-to-one correspondence between photons and electrons.

Hydration number

the number of water molecules an ion can bind via this solvation process, effectively removing them from the solvent and causing them to behave more like an extension of the solute the number of water molecules in a sphere of hydration

Critical Point

the precise temperature and pressure above which liquid and gas phases become indistinguishable. At this point liquid and gas phases cease to exist, merging into a single phase called a super critical fluid liquid and gas phases cease to exist, merging into a single phase

s-block

the s-block is the first two columns

Melting Point

the temperature at which a solid changes into a liquid the temperature at which a substance changes state from solid to liquid. However, it is very important to realize that melting point and freezing point are exactly the same thing. You might think of freezing point as the temperature at which a liquid changes into a solid, but the value measured for mp or fp is simply a temperature, which indicates no direction of progress. For any substance, mp = fp.

Strength of the Field (gravity)

• For gravity near earth: g = F/m (from F = mg) --- For constant E-field: E = F/q (or E = V/d) • For real gravity: g = Gm/r2 --- For point charge E-field: E = Kq/r2

w=−pΔV

where P is the external pressure on the system, ΔV is the change in volume. This is specifically called "pressure-volume" work

KE = 3/2kBT

where kB is Boltzmann's constant; this shows the direct relationship between temperature and kinetic energy) Temperature = The average kinetic energy of the molecules. Many questions, for example, substitute a phrase such as "an increase in the average kinetic energy of the molecules" for the phrase "increase in temperature." Most students who read that phrase will not immediately recognize it as another way of saying "temperature." Increase in Avg KE= Increase in tempreature

Relationship between Free energy and Chemical Energy

∆G° = -nFE° ---n = number of moles of ELECTRONS transferred in a BALANCED redox reaction --- F= Faradays constant Faraday's Constant = the charge on one mole of electrons. positive E˚ = negative ∆G = spontaneous reaction A positive Cell potential means that a species will WANT to be reduced, it is more spontaenous towards a redox reaction, this looking at the equation, that is why a + E˚ = -∆G, which a -∆G is a spontaneous rxn.

(Springs) F = k∆x

(where ∆x is the displacement of the spring from its equilibrium point, NOT the overall length of the spring)--- For F, use the force applied in one trial, or the difference in the force applied between 2 trials F is force, x is length of extension/compression, k is constant proprtionality

∆G° = -nFE°

---n = number of moles of ELECTRONS transferred in a BALANCED redox reaction --- F= Faradays constant Faraday's Constant = the charge on one mole of electrons. ---F= ∆G°/(-nE°) ---Faraday's constant is the charge on one mole of electrons. ---One mole of electrons is 6.022 x 10^23 electrons. Each electron has a charge of 1.6 x 10^-19 C. ----Therefore, the charge on one mole of electrons is: (6 x 10^23 Moles)(1.6 x 10^-19 C) = 9.6 x 10^4 C/mol.

Energy Levels & Photon-Light Emission

Because energy levels are quantized, you cannot cause an electron to move up one energy level unless you add an amount of energy equal to the difference in energy between the current energy level and the higher energy level. If an electron is struck by a photon with an energy that is lower than the difference in energy between two energy levels in that atom the photon will pass through the atom without being absorbed. If an electron drops to a lower energy level, energy is released as a photon (i.e., as electromagnetic radiation). The energy released will be EXACTLY equal to the difference between the two energy levels. IN ORDER FOR THE ELECTRON TO BE FREED FROM THE NUCLEUS, IT NEEDS TO BE HIT WITH ENOUGH ENERGY THAT IS NOT ONLY EQUAL TO THE ELECTRON ENERGY LEVEL, BUT MUST BE IN EXCESS FOR TEH ELECTRON TO BE FREED. IT'S ALL ABOUT USING ENOUGH ENERGY FOR THE DIFFERENCE BETWEEN 2 ENERGY LEVELS, AND WHEN IT DOES HAPPEN, A PHOTON IS SHOT OUT WITH ENERGY REPRESENTING THAT DIFFERENCE.

Boiling Point Elevation:

Boiling point of liquid is elevated when a non-volatile solute is added according to: ---∆T = kbmi ; - kb is a constant - m is molality (NOT molarity) - i is the number of ions formed per molecule (a.k.a., The Van't Hoff Factor; i.e., for NaCl i = 2; for CaCl2 i = 3).

The Work Function in Energy Levels

Bombarding certain metals with energy can cause the ejection of an electron from their outermost shell (i.e., valence electron). The amount of energy required to do this is called the "work function," and is usually given the variable φ. This may sound similar to "Ionization Energy." However, they are NOT the same. Ionization energies are measured for lone atoms in a gaseous state. The work function refers specifically to valence electrons being ejected from the surface of a solid metal. If the energy added is less than the work function, the electron won't be ejected. If it is greater than the work function, the excess energy will be transferred into the kinetic energy of the ejected electron. KE = E - φ ; where E is the amount of energy added and KE is the kinetic energy of the ejected electron. Because energy is usually added via bombardment with photons, E can be replaced with hf, the formula for the energy of a photon. E = hf ; where E = the energy of a photon, h = Planck's Constant (which is always given) and f = frequency.

Other Derivations of the Ideal Gas Law:

Boyle's Law: P1V1 = P2V2 (assumes constant temperature) Charles' Law: V1/T1 = V2/T2 (assumes constant pressure) Note: We find the two laws above to be of limited value for the MCAT because the relationships they demonstrate can be intuited from either the Ideal Gas Law or the Combined Gas Law.

Beta Decay

A neutron is changed into a proton with the ejection of an electron. The neutron is changed to a proton to help keep it at the correct atomic mass number. THat is why the neutron converts to a proton

Galvanic Cells

Also known as Voltaic Cells Galvanic cells convert chemical energy into electrical energy. A current can be generated by using the reduction potentials (E° potential) between two metals, and generate a current along a wire that connects two metal electrodes submerged in solutions that contain metal ions. Why a salt bridge is necessary: ---In the cell above notice that over time there will be a buildup of negative charge in the copper vessel due to continual loss of copper cations, and a buildup of positive charge in the zinc vessel due to the continual production of zinc cations. This polarity resists the flow of electrons and would eventually shut down the cell if a salt bridge were not present. Within the salt bridge sodium ions can flow toward the copper vessel and nitrate ions can flow toward the zinc vessel, neutralizing the buildup of charge and allowing electron flow to continue. The metal cations themselves, as well as any other ions in the solutions, can also flow through the salt bridge. In an electrical sense, the salt bridge connects the circuit, allowing continual flow of electrons from electrode to electrode and then back through the salt bridge via ion diffusion.

Cyanide

CN-

Carbonate

CO3^2-

Springs and Calculating the Spring Constant

Calculating the Spring Constant from Hanging Weights: To calculate the spring constant, solve for k using Hooke's Law. For ∆x, enter the displacement from the equilibrium point for one trial, or the difference in displacement between two trials. For F, use the force applied in one trial, or the difference in the force applied between two trials. CAUTION: It is a common mistake to plug in the mass of the block hanging on a spring for the force. You need to convert that mass into a force using F = mg. Q40. A student hangs a 4 kg mass on a spring and it stretches 1 m. What is the spring constant, and how far will the spring stretch if he attaches a 2 kg mass? -The gravitational force downward equals the spring force upward, mg = k ∆x; solving for k, k = mg/∆x = 4 x 101 N/m, or 40 N/m. The gravitational force is halved, so the balancing spring force must also be halved. Since the spring force is proportional to displacement, it too is halved. Thus the displacement is 1/2m.

Titration Curves: Strong Acid titrated with a Strong Base

A strong acid in the flask will result in the pH being low, around 1 to 2 depending on the [SA]. As strong base is added, the pH will stay low and slowly rise until the equivalence point is reached and then it will go straight vertical for around 6 pH units. The middle of the equivalence region will be pH 7. After the equivalence point, the plot will slowly go to higher pH as more strong base is added

Use a rxn coordinate diagram to explain why the heat of combustion is greatest for the most unstable molecules

Carbon dioxide and water, compared to most other reactants or products, are very stable. Therefore, whenever you graph a combustion reaction you will expect the products to be very low on the y-axis (Energy). The heat of combustion, ∆Hcombustion, for the reaction will be equal to the difference in height between the products and reactants. So, the more unstable the starting products are, the higher they will be on the graph, and therefore the greater will be the difference in height between products and reactants.

Alternating Current vs Direct Current

AC vs DC Direct current is the direct flow of current through a circuit form + to -, or if it is an e- flow, then - to + --- It is used in automobiles because power comes directly form the battery --- If something uses a battery, IT IS DC CURRENT ----- examples- automobile electronics, cigarette lighters, cell phone Alternating current is that the polarity of the voltage and direction of the current periodically reverse, it creates a graph of current versus time for an AC through a sine wave --- Room mean Square- Calculating both voltage and current are necessay for AC because current and voltage over time are sinusoidal, thus having an origin of zero. This means you could have a 120 V in one instant and a voltage of -120V in the next, thus averaging out to be zero.

Acidity

ALways look at the stability of the conjugate base STability or lack thereof will be affected by EDG or EWG. Alcohols are weaker acids than water due to donating effect of the R groups RESONANCE STABILIZATION, if there is resonance, it makes it more acidic

Raoult's Law

AS the solute is dissolved the vapor pressure of the solvent decreases. P(A) = X(A)P(A Vapor Pressure w/ a Non-Volatile Solute = (mole fraction of the pure solvent, X)*(Vp of the pure solvent, Vp°) Vp = XVp° Total Vapor Pressure w/ a Volatile Solute = (mole fraction of solvent* Vp° of the solvent) + (mole fraction of the solute* Vp° of the solute). Vp,total = Vp,solvent + Vp,solute = (Xsolvent Vp°solvent) + (Xsolute Vp°solute)

Bases

Abstract protons/ hydrogens Electron dense and have full or partial negative charge strongest base forms strongest, stable bond with hydrogen, aka strong base favors conjugate acid basicity describes how much molecule wants to react but nothing about how quickly it will do so. More connected with thermodynamics, how badly something wants to react. HOw good is the bond! Bascity has to do with stability, so a more unstable base is a stronger base because it wants to create a bond to become stable. examples- NH2-; OH-- ; RO-- ; H:- ; RC:-- ; R3N ; H2O ; NH3

Lewis

Acids accept a pair of electrons bases donate a pair of electrons AlCl3 and BF3 are two common examples of Lewis acids. The electrophiles in all organic chemistry reactions are acting as Lewis Acids. NH3, OH- and anything else with an electron pair to donate will act as a Lewis base.

Bronsted-Lowry

Acids donate protons (H+) bases accept protons (H+)

Arrhenius

Acids produce H+ ions in solution; bases produce OH- ions in solution.

Vacuum Distillation

Air inside apparatus is evacuated to create a vacuum Vacuum distillation is used because it dramatically lowers the boiling point, allowing you to work at more manageable temperatures with substances that have much higher boiling points at atmospheric pressure. This observation is supported by the fact that liquids can be said to boil at the point where vapor pressure equals atmospheric pressure. By creating the vacuum we essentially drive down the atmospheric pressure to meet the vapor pressure.

Air Resistance

Air resistance is the force exerted on projectiles or falling bodies due to actual physical collisions with air molecules. o The following factors affect the magnitude of air resistance: 1) Cross-sectional Area: greater cross-sectional area = more air resistance 2) Shape: less aerodynamic = more air resistance -example- a flat surface vs an arrow surface 3) Velocity: increased velocity = more air resistance. o Always assume air resistance is being ignored, unless it specifically states otherwise in the question stem or passage. As an object falls, it picks up speed. The increase in speed leads to an increase in the amount of air resistance. Eventually the force of air resistance becomes large enough to balance the force of gravity. At this instant in time, the net force is 0 Newtons, thus the object stops accelerating. THINK OF A SKY DIVER...

Aldehydes and Ketones Nomenclature

Aldehydes are named with the -al ending; ketones are named with the -one ending. In either case, the parent chain must be the longest chain that includes the carbonyl. Aldehyde carbons are always considered carbon #1 for numbering purposes. If a ketone must be named as a substituent it is called an "-oxo" group, as in 4-oxopentanal. As has been mentioned previously, MCAT nomenclature primarily requires nothing more than the ability to recognize the necessary suffixes, functional groups, etc., or to be able to draw a molecule given its name. The MCAT has never required examinees to give proper IUPAC names for complex molecules. o Common Names: There are a few common aldehydes and ketones for which the MCAT will use non IUPAC names. These include formaldehyde (HCHO), acetaldehyde (CH3CHO), benzaldehyde (C6H5CHO), and acetone (CH3COCH3).

Ionic Character

All bonds that are not between two atoms of the same element have some ionic character. It is basically a measure of the polarity of the bond. Ionic species such as NaCl have close to 100% ionic character. Covalent bonds between two non-metals of nearly identical electronegativity have close to zero ionic character. Ionic character is due to a difference in electronegativity between the two atoms in a bond. So, a C-C bond, for example, would have zero ionic character. Theoretically, the greatest possible ionic character would exist in francium fluoride.

The Ion Product

Also referred to as the "Solubility Product." The ion product has the same relationship to Ksp as Q does to Keq. Plug in the values for the actual concentrations of each species at some point other than equilibrium (i.e., for an unsaturated or supersaturated solution). If the product is greater than Ksp, you know a precipitate will form. If it is less than or equal to Ksp, then you know that no precipitate will form. If the ion product happens to be exactly equal to Ksp, then the solution must be exactly saturated (i.e., at equilibrium).

Intensity

Amount of energy transported past a given area of the medium over time. Intensity=Power/area a measure of power per unit area. Waves have power because they transport energy from one point to another in a given amount of time. Intensity is proportional to the square of the amplitude and the square of the frequency, whenever a wave transitions from one medium to another there will be some reflection, which reduces intensity,

Aldehydes and Ketones

An aldehyde is any compound containing a carbonyl with one or more hydrogen substituents on the carbonyl carbon. A ketone is any compound containing a carbonyl with two carbon substituents on the carbonyl carbon. Aldeyhdes and ketones can act as H-bond recipients, but NOT as H-bond donors. Aldehydes and ketones do NOT hydrogen bond with one another, but they are both polar and will therefore have much higher boiling points than alkanes. Aldehydes and ketones can act as hydrogen-bond acceptors when dissolved in water, with water acting as the hydrogen bond donor. Therefore, aldehydes and ketones will be far more soluble than alkanes. Major function = electrophiles, their carbonyl carbon being attacked by a nucleophile. Substitution vs. Addition: Aldehydes and Ketones undergo nucleophilic addition due to lacking a good leaving group

Acid Chlorides

Any Compound containing a carbonyl with a chlorine substituent on the carbonyl carbon Nomenclature - oyl chloride for the ending, ex- propanoyl chloride - Formyl Chloride, Acetyl Chloride, Benzoyl Chloride

Esters

Any compound containg OR on carbonyl carbon Nomenclature- Use -oate- example- Methyl Penanoate --- know methy formate, methyl acetate, methyl benzoate --- Esters act as H-bond recipients, but not donors, slightly soluble in water, but less soluble than acids or alcohols

Hypochlorite

ClO-

Chlorite

ClO2-

Perchlorate

ClO42-

Archimedes' Principle

Any object displaces an amount of fluid exactly equal to its own volume (if fully submerged), or to the volume of whatever fraction of the object is submerged (if floating). The weight of the displaced fluid is exactly equal to the buoyant force pushing up on the object. The buoyant force on an object is equal to the weight of the fluid displaced by the object, so every object tis buoyed upwards by a force equal to the WEIGHT OF THE FLUID the object displaces.

Simple Harmonic Motion

Anything that oscillates back and forth, and can be represented by a sine wave graphically, constitutes Simple Harmonic Motion. There are many possible examples of SHM. A pendulum and a mass on a spring are the most common. Almost any circular motion, when viewed from the side, approximates simple harmonic motion. Waves sloshing back and forth in a container can approximate SHM. Molecular vibrations approximate SHM. Essentially, any movement that oscillates about an equilibrium position, and shows the characteristic sinusoidal pattern, qualifies as SHM.

Buoyant Force: Apparent Weight vs Actual Weight

Apparent Weight (AW) = Actual Weight (aW) - Buoyant Force (Fbuoyant) The apparent weight of a submerged object is the actual weight minus the buoyant force: The difference between the actual weight and the apparent weight tells you: 1) the buoyant force, and 2) the weight of that volume of fluid For example, suppose you are told that the density of a fluid is 2.0 g/mL and that a 5 kg object fully submerged in that fluid has an apparent weight of 40 N. The actual weight is 50 N. When we subtract the apparent weight of 40 N, we get 10 N. This is the buoyant force. More importantly, it tells us how much one "objects-worth" of fluid weighs (from #2 above). We already stated that the object weighs 50 N. Since it is fully submerged, that exact same volume of fluid weighs 10 N. If that exact same volume of fluid weighs only 10 N, then we know that the fluid must be 1/5 as dense as the submerged object

Atomic Radius

Atomic size gradually decreases from left to right across a period of elements. This is because, within a period or family of elements, all electrons are added to the same shell. The effect of increasing proton number is greater than that of the increasing electron number; therefore, there is a greater nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling the atom's shell closer to the nucleus. The valence electrons are held closer towards the nucleus of the atom. As a result, the atomic radius decreases.

P=1/f

Optical Power the flexing of the ciliary muscles results in an increase in the curvature of the lens. As the curvature of a lens increases, its focal point decreases. Because power is the inverse of focal length, we know that a more curved lens (i.e., contracted ciliary muscles) produces a shorter focal point and therefore a more powerful lens. Using the same logic as outlined for the previous question, a near-sighted person—because their lens has the shorter default focal length, also has the more powerful lens.

Oxidation and Reduction

Oxidation- Loses Electrons, Loses H+ REduction- Gains electrons, gains H+

Gamma Emission

Gamma rays are usually emitted as a byproduct of the types of decay outlined above. Gamma decay does not change the number of nucleons!

Heat Capacity vs Specific Heat Capacity

Heat capacity is general and can change depending on the values we have. A 400 mL vessel of water vs a 100 mL vessel of water, the 400 mL will have a higher heat capacity than the 100 mL. Specific heat capacity is always specific for substances, example, 1.33 cal/gC for water will always be the same.

Hydrogen BOnding

Hydrogen bond/acceptors: F, O, or N when bonded to a H, can act as either a hydrogen bond donor or hydrogen bond acceptor F, O, N atom with lone pairs that are not attached to a H, (ROR, RCOR, etc), cannot act Hydrogen bond acceptors Alcohols have much higher boiling points and melting points due to hydrogen bonding. So when compared to toher hydrocarbons with similar MW, hydrogen bonding is stronger than other forces

Alpha Hydrogens

Hydrogens on a carbon adjacent to a carbonyl carbon are acidic due to resonance stabilization of the conjugate base When there are two carbonyls separated by a single carbon, Hydrogens on the middle carbon are even more acidic The greater the partial positive charge on the carbonyl carbon, the more acidic alpha hydrogens will be Always lookout for EDG and EWG on the carbonyl carbon An electron donating group on the carbonyl carbon will decrease its partial positive charge and thereby make it less able to stabilize the conjugate base. An electron withdrawing group will make the carbonyl better at stabilizing the conjugate base and therefore the strongest electron withdrawing group would indicate the strongest acid (because it produces the most stable conjugate base).

The Work-Energy Theorem

If a net force does work on a rigid object, the work done on that object is equal to the change in KE of the object W= KE (final) - KE (initial) Focus on ∆E, remember that change of E, in whatever form of energy it may be in, you can figure out work without the work-energy theorem

Light- Conceptual

If you forget which lens is which, you can always figure it out by employing the "packets of light" visualization. Recalling that light going through the lens will be slower than the light going through the air surrounding it, you can predict which way a light ray will bend near the top of the lens and near the bottom of the lens. This will reveal whether the lens diverges or converges light. The MCAT loves to throw curve balls. What if they presented you with a scenario where a lens was submerged in a fluid with an index of refraction greater than that of the lens? Suddenly your memorized rules for converging and diverging lenses would be thrown out the window. If, however, you had learned via a method such as this to conceptualize how photons actually behave at any boundary, such a question would not be any more difficult for you than one given in the traditional format.

Indicators Weak Acids

Indicators are weak acids that change color as they dissociate from HA into H+ and A- To set up a titration, you must know beforehand the approximate pH of your equivalence point; you then select an indicator that will change color at that approximate pH The dissociation of the indicator and the acid/base reaction we are analyzing run simultaneously in the same beaker but are otherwise unrelated. The amount of indicator is so small compared to titrant and analyte that we can assume it has no impact on pH.

L= nλ/2 (harmonics)

L= nλ/2 --- only with a string or pipe with matching ends, both nodes or antinodes --- Gives harmonics n= 1, 2, 3 ---- can be rearranged to give wavelength, λ: λ=2L/n

Ion-Exchange Chromatography

Column or stationary phase is coated with cations or anions Mixture is passed through and oppositely charged ions adhere to the column Target molecules can then be eluted by washing with a salt solution Make the beads the oppisote ion of the protein you want. The protein you don't want goes through the column So if we want the protein that is +, we put in - beads to get it, then the - proteins elute out. The + protein is stuck to the - beads, then we put in a salt to release it.

Reaction Types:

Combination Decomposition Single Displacement Double Displacement (a.k.a. "metathesis reaction")

Anyhydride

Compound with two acyl groups connected to one another by a single oxygen Nomenclature: --Poic Anhydride ex benzoic acid-> benzoic anhydride -- Common names- Formic Anhydride, acetic anhydride, acetic formic anhydride VERY GOOD ELECTROPHILES, due to highly the carbonyl carbons are highly reactive to nucleophiles, due to LG is a resonance stabilized carboxylate ion

Alcohol Acidity

Less acidic than water Acidity increases form tertiary to secondary to primary, meaning a primary is mostly like to give it's H Both trends are explained by the fact that alkyl substituents are weak electron donating groups. When we look at the conjugate base of water there are no alkyl groups donating electron density to destabilize the oxygen with additional negative charge. With primary, secondary and tertiary alcohols there are one, two and three donating groups respectively. Therefore, tertiary alcohols are the least stable because the conjugate base in that case is destabilized to the greatest degree by induction. Carboxylic acids experience the exact opposite effect because the carbonyl is a strong electron withdrawing group. Further (and even more importantly) the conjugate base in the case of a carboxylic acid is stabilized by resonance.

Decarboxylation

Loss of CO2 from beta-keto carboxylic acid, leaves behind a resonance stabilized carbanion This is usually done by catalysis by a base The carboxylate ion usually retakes the hydrogen from the base, forming a keto-enol tautomer.

Carbocations

MEchanism will always proceed through the most stable carbocation (unless peroxide is present) Carbocation Stability: Tertiary > SEcondary > Primary

Count your carbons

Make sure each product has right number of carbons. Pay attention to those rxns that add to or take awa from length of the carbon.

Phase Changes

Phase is distinguishing between a solid, liquid, and gas forms or states of a substance. When molecules are of the same phase: a) same state b) same chemical composition c) structurally homogeneous (same structure) example- carbon can be diamond or graphite, same state and chemical composition, but is structurally different.

Gravity Filtration

Physical separation of a solid (either crystallized product or solid impurities) from a liquid by passing it through filtration paper Fluted filter paper is recommended, it increases surface area for filtration Whether you would want to filter hot or cold would be determined by the conditions. If you are filtering out a solid impurity filtering hot could prevent your product from crystallizing on the filter paper. However, if you are close to the freezing point of the solid then filtering hot could bring impurities back into solution. In other cases you may be trying to capture product that crystallized upon cooling of your reaction mixture. In that case you would certainly want to filter cold or else you would re-dissolve your product.

Triple Point

Point on a phase diagram, shows only point where substance can exist in equilibrium as a solid, liquid, and a gas. precise temperature and pressure at which all three phases (i.e., states) exist simultaneously in equilibrium with each other

Polar Aprotic Solvents

Polar aprotic solvens exibit diple-dipole Solvents solvate only cations well Anions are not well solvated because the solvent cannot hydrogen bond to them DOwn a column of the periodic table increases nucleophilicty in aprotic solvents

Use the Fundamental Thermodynamic Relation to predict the answer to MCAT questions such as:

Q12. If ∆H is positive and entropy change is negative, what will the sign of ∆G be? Q13. If the change in entropy is positive, and enthalpy is negative, the reaction is: a) spontaneous, b) non-spontaneous, c) can be either spontaneous or non-spontaneous depending on temperature. Q14. If a reactant is dissolved in solution, causing the temperature of the reaction vessel to increase, the G for this reaction must be a) positive, b) negative, or c) cannot be determined.

PV=nRT

R = 0.0821 L*atm/mol*K or 8.314 J/mol*K P= Pressure n= Moles V= Volume T- Temperature

R=K[A]^x[B]^y

R = Rate of rxn K= rate constant Orders determined experimentally by data. [A]^x= [B]^y= Overall order =3 https://www.khanacademy.org/science/chemistry/chem-kinetics/reaction-rates/v/rate-law-and-reaction-order

Nucleophilic Attack of Carbonyls

RCOOH + H₂O -> RCOOH₂⁺ + Nu:- → RCONu + H₂O

Hybridization

Definition: Atoms, when bonded, hybridize (i.e., mix) their higher and lower energy valence electron orbitals to form "hybrid orbitals" with intermediate energy. Carbon, for example, has two electrons in the s orbital and two electrons in the p orbital. However, carbon forms four orbitals of equivalent energy when hybridized as sp3. Determining Hybridization: Count the number of sigma bonds and add the number of pairs of unbonded electrons. This number will equal the sum of the superscripts on one of the following hybridizations: o sp, sp2, sp3, sp3d, sp3d2

Velocity of Sound waves in a solid

Densities of solids are way big, so elastic modulus are increased by an even larger factor This proper causes solids to spring back really fast after deformation Sound or compression waves in solids are much faster than sound in waves in gases sound waves increase in velocity when passing through a solid.

Vf=g*t

Determine the velocity of a falling object after a time of t seconds, shown from being dropped at rest.

Switches

Diagonal break in line between circuit components Closed= electrons flow, open - no electron flow

Linear Motion: Displacement and Velocity

Displacement- The shortest distance between two points Distance is simply the units of how far one has travelled, while displacement is distance travelled in a specific direction. Distance is scalar while displacement is a vector. Velocity is the change of distance in a specific direction, which is a vector, and speed is just a measurement of change, not in any specific direction, which makes it scalar. Remember that vectors have magnitude and direction, while scalars only have magnitude. ON THE MCAT, you can treat speed as the same as velocity, ONLY IF the question makes it clear that the distance travelled is along a straight line constant velocity means the following: no acceleration, no net force, all forces sum to zero, no change in direction, object is in equilibrium

Drawing Resonance Structures

Drawing Resonance Structures: o Atoms can never be moved. o Single bonds can never be moved. o All structures must obey the octet rule (excluding the exceptions outlined previously). o All structures must have the same number of total valence electrons (i.e., the number of electrons in bonds plus the number of electrons in lone pairs). This is NOT to say that individual atoms will not change their valence. In one structure they may have a formal charge and in another they may not, but in all structures the total number of valence electrons for the structure as a whole must be constant. o The tail of an arrow showing electron flow during resonance can only start from a lone pair, a double, or a triple bond.

E1/E2=√MW2/√MW1

E1 and E2 can represent either the effusion rate or the diffusion rate of gases 1 and 2 respectively RATE OF EFFUSION or DIFFUSION is INVERSELY proportional to the molecular weight of gas --- The lighter the gas, the faster the rate is --- The heavier the gas, the slower the rate is

∆E = q + w

E= Change in Temp in a system or the total change in internal energy of a system q= THe heat exchanged between a system and it's surroundings w=work done by or on the system

Bascity

EDG increases bascitity, EWG decrease Bascitity

Isobaric vs Isothermal

Isobaric means constant pressure. Isothermal means no heat exchange (i.e., constant temperature).

Resistance

It is similar to the drag in fluids or the friction between solids. It is applicable to heat flow and fluid flow R = ρL/A ; where ρ = resistivity, L = length, A = cross-sectional area Temperature Dependence- --- Good conductors, resistivity INCREASES LINEARLY with TEMPERATURE, only with good conductors or if one is already at room temperature. --- Semiconductors are oppisote- resistivity DECREASES with temperature Wires between any 2 elements in a circuit are assumed to be perfect conductors, meaning resistance is 0. Resistance on the molecular level is a function of the ability of the electron to travel in a free path between atoms The only way to change the resistance is to either: 1) physically remove one or more resistors from the circuit and replace them with other resistors that have different Ohms ratings 2) change the temperature of the resistor. If you were very careful, you could say it this way: "If voltage increases, in order for current to remain constant, I would need to increase the resistance in the circuit." Which is something I could do by adding more resistors.

Q21. If a projectile has an initial vertical velocity of 30 m/s, how long will it be in the air, how high will it go, and what will be its average velocity during the entire trip?

It will take 3 seconds to reach max height, and will be in the air for six seconds total. It will travel an average velocity of 15m/s during the upward trip for 3 seconds, which means max height will be 45m. Its average velocity for the return trip will be equal in magnitude to its average velocity for the upward trip, but opposite in direction, so the average velocity during the entire trip will be 0m/s. Alternately, you could reason that since average velocity is displacement/time, and the displacement of the complete trip is zero, the average velocity is also zero

Metals vs Non Metals

Metals: larger atoms, loosely held electrons, more likely to lose electrons form positive ions. Lustrous, ductile, malleable, conductors of heat and electricity. Ionic bonds with non metals Non-metals: smaller atoms with tightly held electrons. Nonmetals "like" to gain electrons and form negative ions. They have lower melting points than metals, and form covalent bonds with non-metals.

E2 Reaction

Elimination, Bimolecular depeonds on 2 species, thus second order Single step abstraction of a proton with collapse of electros to form a double bond and ejection of leaving group

Energy

Energy is the capacity to do work Kinetic Energy- --KE= ½mv^2 Gravitational PE- ---PE (gravitational)=Gmm/r or mgh Elastic PE- -- PE (elastic)½kx^2 Electrical PE- --PE (electrical)= Kqq/r or qEd or qV PE stored by a Capacitor- --PE (capacitator) = ½QV or ½CV^2 or ½Q^2/C Internal Energy Heat Energy Chemical Energy Mechanical Energy -- ME=KE + PE

Energy Levels

Energy levels represent the energies of the electrons in an atom. They are quantized! In other words, they look like stair steps, and do NOT look like a ramp. Electrons can be in energy level 1 or energy level 2, but never anywhere in between. The need more energy when they go higher in steps, when they then leave down the state, they show a color Ground state is most stable state of atom, excited state is any state other than the ground state of an atom. Electrons in atoms can only change to discrete energy levels

Permangate

MnO4-

Manganate

MnO4^2-

Reduction Synthesis of an Alcohol

Reducing agents like NaBH4, LiAlH4 and H2/pressure reduce a carbonyl to an alcohol NaBH4 can only reduce aldehydes and ketones LiAlH4 and H2/ pressure can reduce aldehydes, ketones, carboxylic acids, and esters

Inorganic Esters

Referred to as oxo acids, such as phosphoric acid, sulfuric acid, nitric acid Be familiar with those structures GTP, ATP, UTP,- inorganic triphosphate esters FADH2, NADH= Disphopshate Esters FMN, DNA, RNA= Monophosphate esters

Alkenes

Focus on general characteristics of alkenes and seeing them prat of beta-oxidation, dehyrdation of alcohols,etc. Anything with a double bond Alkenesact as nucleophiles, the pi electrons will attack, leaving a carbocation on one of the carbons as a carbocation. When located one carbon away from another atom, alkenes are weakly electron withdrawing, meaning there is resonance Alkene stability: Alkyl substituents (R-groups) increase alkene stability - tetra substitued> trisubstituted> monosubstituted> unsubstituted aka more r groups, more stability

Concave (mirror)

Follow the same rules as converging lenses. usually produces a positive, real, inverted image. When the object is inside the focal point it produces a negative, virtual, upright image.

Convex (mirror)

Follow the same rules as diverging lenses. always produces a negative, virtual, upright image.

Triacyglycerol Mechanism

Follows esterification to form triacylglycerols

Calculating pH for Strong Acids/Base

For Strong Acids/Bases: (e.g., pH of a 1 x 10-3M HCl solution) The pH or pOH = -log[strong acid or base] example= -log (1 X 10^-3)= pH=3

solution formation

For a solution to form, the intermolecular forces between the solute particles must first be broken, any intermolecular forces between the solvent particles must be broken to make room for the solute. New intermolecular forces are formed between the solute particles and the solvent particles: -If the new intermolecular forces formed are greater, more stronger/stable, than the sum of the intermolecular forces that had to be broken, the net energy is released and the solution is exothermic and has a negative Heat of Solution ΔHsolution < 0. Heat will be evolved -If the new IM forces are NOT more stable than the old ones, the solution has a positive ΔHsolution. The positive heat of solution means that energy must be added to the system to make the solute dissolve Entropy increases when a solution forms

A pan of water is placed upon an electric heating element on a stove. Describe all types of heat exchange expected to occur in this scenario

Most students will assume the pan of water is cold. However, this is a good reminder that more careful thinking is usually rewarded on the MCAT. If the pot and water happened to be at the same temperature as the heating element then no heat exchange would occur. If the pan was hotter than the element (say the element wasn't even turned on yet), then heat flow would occur in the opposite direction to that most students will propose.

Synthesis of Alkyl Amines

NH3 + CH3Br -> NH2CH3 + HBr o Formation of an alkylamine from an amine and an alkyl halide o STEPS: 1) Ammonia acts as a nucleophile, attacking the alkyl halide via SN2 and kicking off the halide ion. 2) The halide ion acts as a base, abstracting a hydrogen to quench the charge on the nitrogen. o NOTE: This reaction results in many side products because the resultant amine is still a good nucleophile and can react again.

COlloids

NOT SOLUTIONS Colloids are solvents containing UNDISSOLVED solute particles that are too small to be separated by filtration Larger than solute particles in true solution Scatter light, while true solutions do not examples: Paint, dust

Virtual (image)

No actual light emanating from or reaching the image The image formed behind a plane mirror

Electromagnetic Waves

No medium required Capable of propagating in a vacuum Transfer energy and momentum through space (visible light, microwaves, radio waves) - transverse only

SN2 Reaction

Nucleophilic Substitution, Bimolecular Rate depends on the concentration of 2 species, thus 2nd order 1) The single-step "back side attack" of the electrophile with simultaneous ejection of the leaving group.

Hydroxide

OH-

Static vs. Dynamic Equilibrium

Objects at REST are in STATIC equilibrium ---If the combined effect of all the forces acting on a body is zero and the body is in the state of rest then its equilibrium is termed as static equilibrium Objects moving at a CONSTANT velocity are in DYNAMIC equilibrium ---when a body is in state of uniform motion and the resultant of all forces acting upon it is zero then it is said to be in dynamic equilibrium. Net force experienced by the object is 0 in both cases Examples of Equilibrium: -Terminal velocity, constant velocity, objects at rest, balance fulcrums, boards hanging from a string, objects floating in a liquid

sp3d2 hybridization

Octahedral, Square Pyramidal, or Square Planar [90˚]

Chirality

Often referred to as "handedness." Any atom attached to four different substituents must be chiral. Any atom with less than four substituents cannot be chiral (and therefore cannot be an enantiomer). ALso no superimosable, SOmething may have chiral carbons, but if it is superimosable in it's mirror image, ITS NOT CHIRAL!

Reflection

Reflection is the bouncing of a wave off of an interface between two mediums.

Refraction

Refraction is the bending of light at an interface between two mediums with different indices of refraction.

Constructive Interference

Regions where amplitudes of superimposed waves add to each other, increasing amplitude, Constructive interference leads to addition of the amplitudes and thus greater intensity and greater brightness.

Destructive Interference

Regions where amplitudes of superimposed waves subtract from each other, decreasing amplitude. Destructive interference leads to cancellation of the amplitudes and thus zero amplitude, or no light.

Electromagnetic Spectrum order

Remember: Grannies Xylophone Usually Vibrates In Many Room In terms of frequency- -- gamma rays > x-rays > ultraviolet > visible light > infrared > microwaves > radio waves. for wavelength, it is just opposite

SN1/SN2 and E1/E2

Review these patterns SN1 competes with E1 SN2 competes with E2 SN1 does not compete with SN2 or E1 does not compete with E2 a 3' carbon must react via SN1 or E1 mechanism ALWAYS just on the MCAT

Alkanes- Cylic COmpunds

Ring Strain- Cycloalkanes create ring strain because they force bond angles to deviate from the optimum tetrahedral angle of 109.5°. Cyclohexane in its chair conformation has zero ring strain. Cycloalkanes with more or less than six carbons exhibit increasing ring strain as one moves away from six. Very large rings (i.e. 10+ carbons) have enough freedom to again approximate the tetrahedral angle. Bicyclic ring systems generally exhibit more ring strain than do monocyclic rings.

Distillation

Separate two substances by simple distillation, must have boiling points at least 25'c apart

Example of a Coffee Cup Calorimeter

A physics class has been assigned the task of determining an experimental value for the heat of fusion of ice. Anna Litical and Noah Formula dry and mass out 25.8-gram of ice and place it into a coffee cup with 100.0 g of water at 35.4°C. They place a lid on the coffee cup and insert a thermometer. After several minutes, the ice has completely melted and the water temperature has lowered to 18.1°C. What is their experimental value for the specific heat of fusion of ice? The basis for the solution to this problem is the recognition that the quantity of energy lost by the water when cooling is equal to the quantity of energy required to melt the ice. In equation form, this could be stated as Qice = -Qcalorimeter (The negative sign indicates that the ice is gaining energy and the water in the calorimeter is losing energy.) Here the calorimeter (as in the Qcalorimeter term) is considered to be the water in the coffee cup. Since the mass of this water and its temperature change are known, the value of Qcalorimeter can be determined. Qcalorimeter = m•C•ΔT Qcalorimeter = (100.0 g)•(4.18 J/g/°C)•(18.1°C - 35.4°C) Qcalorimeter = -7231.4 J The negative sign indicates that the water lost energy. The assumption is that this energy lost by the water is equal to the quantity of energy gained by the ice. So Qice = +7231.4 J. (The positive sign indicates an energy gain.) This value can be used with the equation from the previous page to determine the heat of fusion of the ice. Qice = mice•ΔHfusion-ice +7231.4 J = (25.8 g)•ΔHfusion-ice ΔHfusion-ice = (+7231.4 J)/(25.8 g) ΔHfusion-ice = 280.28 J/g ΔHfusion-ice = 2.80x102 J/g (rounded to two significant figures)

Polarimeter

A polarimeter is an apparatus that measures the rotation of plane-polarized light as it passes through a sample

Solution Chemistry

A solution is a homogenous mixture of two or more compounds in the same phase. (We usually think of all solutions as being in the liquid, or "aqueous" phase; however, a homogenous mixture of gases is also called a "solution".) Solvent vs SOlute: - Solute is the substance dissolved into solvent - solvent is more abundant than solute

Tautomerization

An enamine and imine interchange via a proton shift analogous to the keto-enol tautomerization

V = λf

Formula for wave speed Wavelength multiplied by frequency

Nitrite

Formula: NO2-

Formulas for Simple Harmonic Motion

Frequency is the number of occurrences of a repeating event per unit time. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. Recall that frequency is the inverse of period, so the above equations can also be used to calculate frequency for these systems. In that case, set frequency equal to the same equation, but inverted Q44. How will increasing the following aspects of a mass-spring system change the frequency of oscillation? a) mass on the spring, b) length of the spring, c) mass of the spring itself, d) gravity, e) the spring constant. -a) increasing the mass will decrease the frequency; b) the length of the spring has no effect as long as it does not change k; c) the mass of the spring itself has no effect, assuming it is far less massive than the massive object attached to it; d) increasing gravity would have no effect; e) increasing the spring constant would increase the frequency. It is helpful to substitute 1/f for T in the formula for these types of problems. This will make the correct relationships easy to see. Notice that the MCAT likes to tempt you to mix up the variables that uniquely impact mass spring systems, but do not similarly impact pendulums. Q45. How will decreasing the following aspects of a pendulum change the frequency of oscillation? a) mass of the pendulum bob, b) length of the pendulum, c) gravity. - a) decreasing the mass of the bob will have no effect; b) decreasing the length of the pendulum will increase the frequency; c) decreasing gravity would decrease the frequency.

Semiconductor

Material right in the middle of insulator and a conductor in terms of conductivity vs. resistivity

Resistor

Material that impedes flow of e- Even the best conductors exhibit some small degree of resistance to the flow of e- and even resistors do conduct e- to some small degree An electrical device that resists the flow of electrical current

Q1. Which is stronger, a sigma bond or a pi bond? Why?

Pi bonds themselves are weaker associations than are sigma bonds. However, a double bond (one sigma bond plus one pi bond) is stronger together than a single bond (one sigma bond only). Also, triple bonds are much shorter, stronger bonds than are single bonds, but are also more reactive. Reactivity has to do with the tendency of the third bond (a pi bond) to react. Bond strength is a measure of the energy needed to completely break the two atoms apart (i.e., break all three bonds). Sigma bonds are significantly stronger than pi bonds. This is because sigma bonds allow for electron density to be concentrated to a much larger degree between the two nuclei. The lowest energy state for an electron electrostatically attracted to both nuclei is between those two nuclei and as close to each nucleus as possible. In a pi bond the p orbitals overlap above and below the atom, localizing the electrons above and below the plane of the bond—a higher energy state compared to the head-on overlap of a sigma bond. You can also conceptualize that pi bonds are weaker simply because we know those electrons are in a higher-energy state. It is universally true that when a bond is higher in energy it will require less energy to break it.

Specific Rotation

Specific Rotation takes these factors into account by dividing observed rotation by the length of the tube and the concentration. Specific rotation could therefore be described as "observed rotation per length, per concentration unit."

Critical Pressure

THe pressure at the critical point the highest vapor pressure that a liquid can have (the vapor pressure of a liquid at the critical temperature)

Real (image)

There is actual light at the image (e.g., an image formed on your retina)

Conformational Isomers

These are NOT true isomers! They are the same exact molecule. When a molecule twists or rotates around its bonds these are considered "conformers" NOT isomers. Any compounds that have the same molecular formula and the same connectivity but that differ from one another by rotation about a sigma bond; conformational isomers are the exact same molecule

Two Lens Systems

(e.g., binoculars, telescopes, etc.) The image formed by the first lens becomes the object for the second lens.

sp hybridization

50% p character and 180 degree ideal bond angle

Positron Emission

A proton is changed into a neutron, with expulsion of a positron. We are doingP+N and P-1, we are reducing a number of protons. similar to electron capture

d=.5*g*t^2

Distace that a free falling object has fallen from a position. (1/2)at^2

Electrophiles

Electron poor species with full or partial positive charge accepts electrons from nucleophiles or bases, H+ ; R2C=O ; RX ; X2 ; HX ; R3C +

Hydraulic Lifts

Fm= mg(h1/h2) or Fm= mg(A2/A1) h1 & h2 refer to distances traveled by large plunger and small plunger respectively A1 and A2 refer to cross sectional areas of large plunger and small plunger respecitvely

Electrical Potential Energy (gravity)

For gravity near earth: PE = mgh ---For constant E-field: PE = qEd • For real gravity: PE = -Gmm/r^2 --- For point charge E-field: PE = Kqq/r^2 (attractive if it involves opposite charges, and repulsive if it involves like charges)

Attenuation

Gradual loss of intensity as a wave passes through a medium In non-dispersive mediums this is due to scattering/ reflection of some waves and absorption of wave energy

SN1 Reaction

Nucleophilic substitution, unimolecular KNow mechanism Depends only on concentration of one species, is thus first order 1) The dissociation of the leaving group, resulting in formation of a carbocation [slow step]. 2) Attack of the carbocation by the nucleophile [fast step].

Vf = √(2gh)

Velocity of a particle at the base of an inclined plane formula for acceleration down an inclined plane -a = gsinθ The formula V = √(2gh) is derived from the law of conservation of energy by equating mgh to (1/2)mv2 and solving for v. As long as friction and air resistance are ignored, energy will be conserved, whether the object falls directly to the ground, or rolls down a plane.

x=λL/d

x= distance between 2 fringes L= distance between the double slit and the final screen λ= wavelength of light used d= distance between two slits This formula focuses on seeing relationships, how when you change wavelength, distance between slits, will alter the pattern of fringes produces

∆Energy = W + Q

∆Energy = W + Q. Work= energy transfer via a force Heat= energy transfer via energy flow form hot to cold 1st law of thermodynamics: Energy change is not always completely due to work, some energy is often lost to heat. Work and heat are the only two ways energy can be transferred into or out of a system, often, this law is simply as the formula above

Charge

(-) charge= extra electrons (+) charge= relatively fewer electrons Positve charges are NOT little mobile masses with an inherent charge: this is a positron. While protons do fit the concept of positvely charge mass, CHARGES IN THIS SENSE ARE NOT PROTONS OR POSITRONS POSITIVE CHARGE IS ALWAYS A LACK OF ELECTRONS (-) charge is ALWAYS a SURPLUS of ELECTRONS ---ex- In a battery, (+) pole is electron deficient, thusneed more electrons to become neutral. (-) pole has excess electrons and would need to lose electrons to become neutral. Either atoms of material itself lack electrons ( cations/ fewer electrons than protons) or you are comparing a place of high electron density to a place of low electron density: it is never about actual positrons or protons moving around Misconceptions: --- Positive Charge in a battery: we say that one terminal of a battery is positive and the other is negative. Is the positive terminal positive because it has a large number of positrons? NO. It's due to electron deficiency in relations to other terminal --- Positively charged ions: Cations are (+) charged. Not due to excess positrons or protons, but due to electron deficiency: FEWER e- THAN protons ---Positive Charge as part of a dipole: Is the (+) side of polar bond (+) due to more positrons or protons? NO. Positive due to e- pull toward side of MORE electronegative atom, thus (-) side has more e- density and (+) side is slightly deficient in e- compared to normal ---Moving positive charges: When you see (+) charges lined up on surface of an object, this is often seen as induction or static electricity. these are NOT isolated protons or positrons: it is atoms deficient in e- and thus bear (+) charges. CHARGE IS QUANTIZED AS = e- = 1.6 X 10^-19 C

Calculating pH for Weak Acids

(e.g., pH of a 1 x 10-4M CH3COOH solution) 1) Write out the equilibrium equation (HA <-> H+ + A-). 2) Use x to represent the concentration of each of the two products (or 2x, 3x etc. depending on the coefficients in the balanced equation).- AKA BALANCE OUT THE EQUATION 3) Use "[HA] - x" for the concentration of the original acid. 4) Solve for x from the resulting equation: Ka = (x)(x)/[HA - x]. 5) If this results in a quadratic equation, assume that x is much smaller than [HA] (in step #3 above) and omit it. 6) Use -log[H+] to solve for the pH.

Fischer Projection

(horizontal lines project out of the page; vertical lines project into the page)

PE=-Gm1m2/r

(in space, or near the earth if one is NOT assuming g = 10m/s2) The negative sign is necessary because, without it, the formula would predict that as r increases, PE decreases. If you have an even basic concept of PE, you will see that this cannot be. A rock gets more PE as it gets farther from the center of the earth, not less. The negative sign makes it so that as r increases, we get a smaller negative number, which is actually a larger value. A negative value approaching zero is growing PE.

Step-by-Step Instructions for Balancing a Reaction:

1) Balance the number of carbons 2) Balance the number of hydrogens 3) Balance the number of oxygens 4) Balance the number of any remaining elements 5) If necessary, use fractions. For example, if you have seven oxygens on one side of the reaction and one O2 on the other side, put 7/2 in front of the O2. 6) Multiply all of the species on both sides of the reaction by the denominator of any fractions. 7) Double check your work by counting the number of atoms of each element found on each side of the reaction. One of the most common errors is failure to multiply by a coefficient. For example, you might accidentally count 2CO2 as 2 oxygens when there are actually 4 oxygens present. THE MCAT WILL GO YOU UNBALANCED REACTIONS..

Deriving a formula from percent mass

1) Change the percent mass for each element into grams (i.e., 15% = 15g), always do it out of 100g, its the easiest 2) Convert the grams of each element into moles by dividing by molar mass. 3) Look at the element with the lowest number of moles. Calculate approximately how many times it will divide into each of the other molar amounts for each of the other elements—this number will be the subscript for each element in the empirical formula. If the subscripts are not at their lowest common denominator, reduce to get the empirical formula. An empirical formula is all you can get from percent mass alone. To get the molecular formula, you must be given the MW of the unknown compound. If you have the molecular weight of the actual compound, simply divide that MW by the MW of the empirical formula. You should get a whole number. Multiply each subscript by that number to get the molecular formula.

How to solve a linear motion problem in your head:

1) Conceptually define acceleration: Acceleration is the change in velocity each second; or the change in m/s each second; or the "rate of change" of velocity. Because we know how velocity changes for all bodies under the influence of earth's gravity (10 m/s each second; ignoring air resistance), we can predict velocity at any time period. 2) Learn how to calculate average velocity quickly. To find average velocity, simply take the initial velocity and add it to the final velocity, then divide by two. You will only consider the upward half of the motion, or downward half of the motion, and then one of them will always be zero. Vavg = (V1 + V2)/2. 3) Calculate the distance (or height) traveled using Distance = rate*time. In steps 1) and 2) above, you just calculated the average velocity (rate) and the time. Multiply these together and you'll know exactly how far (or how high) the object traveled.

To calculate the "order" of each reactant using experimental data:

1) Find two trials where the [reactant] in question changed, but all other parameters did NOT (i.e., the concentrations of the other reactants, temperature, pressure, etc., all remained constant). 2) Note the factor by which the reactant concentration changed. 3) Note the factor by which the rate changed across those same two trials. 4) Solve for Y in the following equation: XY = Z ; where X = the factor by which the [reactant] changed, Z = the factor by which the rate changed, and Y = the order of the reactant. Recall that any number raised to the zero power is equal to one.

Linear Motion Graphs- The Steps for Interpreting Linear Motion Graphs

1) What does the slope represent? - 2) Is this slope (+) or (-)? What does the sign of the slope tell you? - The sign of the slope on a velocity vs. time graph tells us the sign of acceleration. This tells us which direction the acceleration vector points, and hence the direction of the net force. However, it tells us absolutely nothing about which way the particle is moving. Remember that velocity and acceleration can be—and often are—oriented in opposite directions. 3) Is the slope constant (straight line) or non-constant (curved line)? What does this observation tell you? -constant=equilibrium, which means NO acceleration 4) What value is on the y-axis? - Students tend to forget this important information. It is the quantity on the y-axis that is changing. If we see a flat line with zero slope, this means that whatever is on the y-axis is constant. 5) Is the y value (+) or (-) (i.e., is the line above or below the x-axis?). What does this observation tell you? -For example, on a displacement vs. time graph, when the line is above the x-axis, displacement is positive and the object is to the right of the origin. When the line is below the x-axis, displacement is negative and the object must be to the left of the origin. On a velocity vs. time graph, the location of the line above or below the x-axis tells you the sign of the velocity, regardless of whether the object is moving to the right or to the left. 6) Do you expect the value on the y-axis to be large or small at the beginning? - For example, for a ball being thrown up into the air, many students will pick an erroneous velocity vs. time graph that features a line starting at the origin. That's impossible. If initial velocity is zero, the ball won't travel upward! Velocity should have a large magnitude (i.e., high on the yaxis) at the beginning, and then decrease with time.

Amine Nomenclature

1)Name the alkane to which the N is attached (e.g., propane) 2) Add "amine" in place of the "e" on the end of "ane" (e.g., propanamine). It is also acceptable to separate the substituent name (e.g., propyl amine) 3) If the amine is secondary, the longest chain is included in the name as indicated above. The other chain is added at the beginning, proceeded by the letter "N-" (e.g., N-ethylpropanamine) 4) If the amine is tertiary or quaternary, add additional substituents to the front of the name in alphabetical order, all with the prefix N- included (e.g., N,N-diethylpropanamine, or N-ethyl-N-methylpropanamine, or N,N-dimethyl-N-ethylpropanamine)

Solving circuits using Ohm's Law: FIRST

1st- Have a simplied circuit: combine circuit compnents in following rules: -- Resistor in series: add resistance of each resistor directly ---- Rtotal= R1 +R2 + R3 -- Resistors in parallel: Add inverse of resistane for each resistor, take inverse of sum --- 1/Rtotal= 1/R1 + 1/R2 + 1/R3 --Capacitors in series: add the inverses of the capacitance for each capacitor, then take the inverse of that sum --- 1/Ctotal = 1/C1 + 1/C2 + 1/C3... --Capacitors in parallel: add the capacitance of each capacitor directly ---Ctotal = C1 + C2 + C3... -- Batteries in series: add the voltage of each battery directly; however, current (Amps) and capacity [amp-hours, (Ah)] will remain the same ---Vtotal = V1 + V2 + V3... --- Batteries in parallel: add current (Amps) or capacity (Ah) for each battery directly, but V remains the same ------Ex- If you wire 2 12 V battereis with a 50 Ah capacity together in series, you get 1 24V battery and 50 Ah capacity. If you wire same two 12 V battereis in Parallel, you get the one 12 V battery and twice the capacity, 100 Ah.

Hydrogen Half Cell

2H⁺ + 2e₋ → H₂ E° = 0.00 Volts E° values assigned to each half-rxn represent the relative reduction potential, aka the potential to gain e-, of that species compared to the E° of two H ions to gain 2 e- to form H gas This standard, the Hydrogen half-cell, is the standard which ALL other half rxns are compared, and it's E° is defined as E°= 0.00 V. Always compare half rxns to E°= 0.00 V. --- A species with + E° is more likely to gain e-, aka be reduced, than hydrogen ions --- A species with negative E° is less likely to gain e- than Hydrogen ions. It is all about what is compared to: a - reduction potential can be reduced as long as long it has a greater reduction potential than the species it is compared with: ex- -1.5v vs -1.8v, species -1.5v is reduced and species -1.8V is oxidized, so thus you do -1.5 + 1.8 and you get .3V, showing the cell potential, which is positive in this situation, would proceed spontaneously in a galvanic cell. FOr the MCAT, remember cations Cu⁺, Fe⁺,etc get reduced to form solid metals Cu (s), Fe(s), etc and solid metals get oxidized to form cations, but solid metals are NOT reduced

Catalysts:

A catalyst is any substance that increases reaction rate without itself being consumed in the process. Rate Laws for Catalyzed Reactions: Technically, the rate law is the sum of the rate law for the uncatalyzed reaction and the rate law for the catalyzed reaction. This fact, however, can usually be ignored, and you can assume that the rate law for the reaction is exactly equal to the rate law for the catalyzed reaction alone. Under such an assumption, write the rate law in the same way as normal, with the concentration of the catalyst added in as a reactant. The rate constant, k, is sometimes replaced with kcat. What do catalysts change?-They don't change Ea, but provide an alternate route that has a lower Ea What do they not change? -They do NOT change the equilibrium, Keq, enthalpy change, entropy change, Gibbs free energy, or any other thermodynamic properties.

Coordinate Covalent Bonds

A coordinate covalent bond is one in which both electrons shared in the bond are donated by one atom. metal ion complexes, several Lewis bases "donate" their "free" pairs of electrons to an otherwise naked metal cation, which acts as a Lewis acid and "accepts" the electrons. Dipolar bonds form and the resulting compound is called a coordination complex, and the electron donors are called ligands. Usually more than one of these "donor" molecules (i.e., Lewis bases) surround and bind a single "recipient" molecule (i.e., Lewis acid; usually a metal). For the MCAT, if a molecule does not have a lone pair of electrons it will NOT participate in a coordinate covalent bond. The complex formed by the metal and the molecules forming coordinate covalent bonds with that metal is called a "coordination complex."

Electric Dipoles

A dipole is a separation of (+) & (-) charges of equal magnitude When MCAT discusses dipoles, they will either be two opposite charges of equal magnitude very near one another in space, or any object/molecule with a charge separation, wherein one side bears a full or partial (+) charge or another side bears a full or partial (-) charge. When a dipole is exposed to an electric field, it aligns itself with that field A dipole that is NOT aligned with the electric field has POTENTIAL ENERGY because alignment with the field is a lower energy state than alignment against the field

Heating Curves

A graph of temperature (T) in Kelvin or Celsius vs. heat (q) in Joules. Occasionally, time is graphed on the x-axis instead of heat (if heat is added at a constant rate the temperature vs. heat graph and the temperature vs. time graph look approximately the same) the x-axis is usually a measure of the heat added/absorbed, but time can also be represented on the x-axis. The horizontal sections of the graph represent phase changes. The first flat section will represent the phase change between solid and liquid and the second will represent the phase change between liquid and gas. The graph remains flat during a phase change because changing the state of a substance requires energy. If heat is on the x-axis then the length of the first horizontal section represents the heat of fusion and the length of the second horizontal section represents the heat of vaporization. The slope of the lines between these horizontal sections represents the inverse (∆T/Q) of heat capacity (Q/∆T) for that particular phase of the substance. One should observe, therefore, that different phases of the same substance usually have different heat capacities—as indicated by the differing slopes of those sections of the following graph: THERE IS NO CHANGE IN TEMPERATURE DURING PHASE CHANGE, all the energy goes into breaking IM forces and none goes toward an increase in temperature

Racemic Mixture

A mixture that contains equal amounts of the (+) and (-) enantiomers. Racemic mixtures are not optically active.

A certain mixture has a large negative heat of solution. Describe the relative strength of a) the intermolecular forces between solvent molecules, b) the intermolecular forces between solute molecules and c) the intermolecular forces between solute and solvent molecules. Would you expect such a solution to have a higher or lower vapor pressure compared to a mixture with a positive heat of solution?

A negative heat of solution tells us that the dissolution releases heat. In order for this to occur, the solvent-solute bonds must be relatively stronger than the solvent-solvent and solute-solute bonds that had to be broken in order to dissolve the solute into the solvent. We would expect such a solution to have a lower vapor pressure than a solution with a positive heat of solution because—as stated at the outset—the negative heat of solution indicates strong solvent-solute interactions. It is these very intermolecular forces that must be overcome in order for solvent molecules to escape into the vapor phase. For a solution with a positive heat of solution, these attractions are relatively weaker, and therefore (at the same temperature) more of the molecules should have enough energy to enter the vapor phase.

Pendulums

A pendulum is any weight (often called a "bob") attached by a rod, string, wire, etc., to a fixed overhead point, and capable of freely swinging from side to side. Potential Energy (PE) is at a maximum at the maximum height of the bob, and is at a minimum at the bottom of the pendulum's arc. Kinetic energy (KE) is at a maximum at the bottom of the pendulum's arc and is at a minimum at the maximum height of the bob. Gravitational potential energy is usually assumed to be zero for a pendulum bob at the lowest point of its arc. In other words, at that point we assume that h = 0. What portion of the movement of a pendulum represents one cycle? - One cycle for a pendulum would be movement of the bob from one side to the other, and then back to the starting point. Many students make an error in thinking that one swing to the other side (without the return swing) is one cycle. Once clue to thinking of this correctly is the fact that the movement must be periodic, and therefore it must repeat. When the bob is swinging back, it is doing something it has not done before. Once it gets back to the starting point, however, it is repeating the same motion; the time to do this complete, non-repetitive motion is defined as one period What value must be low for a pendulum to exhibit Simple Harmonic Motion? - The angle of displacement must be small for SHM Why does the displacement of the pendulum gradually decrease over time? - The pendulum will not continue oscillating to the same height because of the influence of non-conservative forces such as air resistance. Energy lost to these sources is not available to the bob, so it cannot travel to its original height (or attain its original PE). a=-gsin(theta)

Specific Gravity

A ratio that describes how dense something is compared to water, the ratio of one density to another density. The specific gravity tells you the fraction that will be floating under water. ex. since ice has a S.G. of .92, 92% of an ice cube is under water. If a S.G. is >1, 100% of the object is submerged SG = Dsubstance/DH2O The density of a substance divide by the density of water For objects floating in liquids, the fraction of the object submerged = the ratio of the density of the object to the density of the liquid. If the liquid in which it is submerged is water, the fraction submerged is equal to the specific gravity. Q46. A ball is floating ¾ submerged in a liquid with a density of 2.0 g/cm3. What is the specific gravity of the liquid and the density of the ball? -Because the ball floats with ¾ of its volume submerged, it must be ¾ as dense as the liquid. Therefore, the density of the ball must be 1.5 g/cm3. This is 1.5 times as dense as water, so the SG of the ball is 1.5, and the SG of the liquid is DLiquid/DH2O = (2 g/cm3)/(1 g/cm3) = 2

Acceleration

Acceleration is any change in velocity. Acceleration describes how quickly the velocity is changing, not the magnitude of the velocity itself Acceleration has to do with changing how fast an object is moving. If an object is not changing its velocity, then the object is not accelerating. Acceleration is 10 m/s^2 and is ALWAYS negative in vertical projectile motion, meaning it is always working AGAINST a positive vector because of GRAVITY. Gravity is downward. The acceleration of a projectile is always downward... If there is no net force, there can never be acceleration according to Newton's Second Law there CAN be a force and no acceleration if there are other forces to counteract it. If force increases, acceleration increases (all other forces and factors remaining unchanged). If force increases linearly, acceleration increases linearly. If force increases exponentially, acceleration increases exponentially. If there is no acceleration, there could be a force acting on that object. However, if there is a force, we would know that it must be exactly canceled out by the sum of the other force vectors on that same object (i.e., the object must be in equilibrium). a change to either magnitude or direction constitutes a change—and therefore acceleration constant acceleration happens due to the velocity is changing by a constant amount each second. An object with a constant acceleration should not be confused with an object with a constant velocity. Don't be fooled! If an object is changing its velocity -whether by a constant amount or a varying amount - then it is an accelerating object. And an object with a constant velocity is not accelerating. ex- Walking at a constant speed around a corner constitutes acceleration due to the change in direction.

Newton's Third Law

Action-Reaction For every action, there is an equal and opposite reaction to the first object. Even if things are still different sizes, Newton's third law still stands. Even if the force is the same and there are different sizes, acceleration is what maintains this... Whenever one object exerts a force (action) on a second object, the second object always exerts an equal and opposite force (reaction) on the first object. -AKA FOR EVERY FORCE, THERE IS AN EQUAL AND OPPISOTE FORCE, so each object will feel forces exerted on each other. There are force pairs, that are always on different objects. The forces don't cancel each other out because the FORCES are on DIFFERENT objects! Examples- Examples of action-reaction pairs include: any contact force between two objects; gravitational force between any two objects (regardless of mass); electrostatic force between two charged particles (regardless of charge); magnetic force between two objects; plus many other possible scenarios. Car crashing a car, cheerleader getting hit, baseball bat hitting a ball

Acid-Base Equilibria:

All equilibrium constants (Keq, Ka, Kb. Kw or Ksp) are written via the law of mass action, with pure liquids (l) and solids (s) OMITTED think of Ka or Kb just as you do Keq. A large Ka (or a small pKa) indicates that at equilibrium there are far more products than reactants. For an acid dissociation, this would mean a lot of dissociation (i.e., a lot of H+ formed) and thus a very strong acid. -aka large Ka or small pKa, ALOT OF DISSOCIATION Similarly, a large Kb (or a small pKb) indicates a very strong base (i.e., a lot of OH- formed—either from dissociation of a hydroxide base such as NaOH, or from deprotonating water). The acid-base equilibrium constant, Ka, is a constant (as the name suggests) for a given reaction at a given temperature, and therefore the negative log of that constant would also be a constant.

Sound Resonance

All objects have natural frequencies at which they will vibrate when distrubed some objects produce a random array of dfiferent vibrational frequencies Other objects like musical instruments, vibrate at non-random natural frequencies which are at interger multiples of a number, 200Hz, 400 Hz, 600 Hz, 800 Hz. These frequencies are called harmonics When one object is vibrating near another object, it can cause the neighboring object to begin vibrating at that same frequency If the exact frequency at which the second object is caused to vibrate happens to be one of it's natural frequencies or harmonics, then two objects are in resonance. Constructive interference, 2 instruments can produce a much louder sound. If the 1st object causes a vibration in the 2nd object that is NOT a match to one of its natural frequencies, resonance does NOT occur.

Strong Base

All strong acids and strong bases dissociate 100% in water (making them good electrolytes). There is obviously a continuum of strength, not a hard, fast line, but for the MCAT we will consider a species "strong" only if it is included in the following lists Group IA hydroxides (NaOH, KOH, etc.), NH2- , H-, Ca(OH)2, Sr(OH)2, Ba(OH)2, Na2O, CaO.

Strong Acids

All strong acids and strong bases dissociate 100% in water (making them good electrolytes). There is obviously a continuum of strength, not a hard, fast line, but for the MCAT we will consider a species "strong" only if it is included in the following lists HI, HBr, HCl, HNO3, HClO4, HClO3, H2SO4, H3O+

α-β Unsaturated Carbonyls

An aldehyde or ketone with a double bond between the alpha and beta carbons. In terms of the MCAT, you should think of an α-β-unsaturated carbonyl as an electrophile. Nucleophiles either attack the beta carbon directly, or attack the carbocation that exists in the second resonance form. It might be tempting to think of the double bond between the alpha and beta carbons as a nucleophile that will undergo electrophilic addition. However, the withdrawing effect of the carbonyl decreases the electron density of the double bond deactivating it toward electrophilic addition. o STEPS: There are two possible ways to visualize this mechanism, based on which resonance form you start with: 1) With the double bond between the alpha and beta carbons, the nucleophile attacks the beta carbon, pushing the double bond over one carbon and forcing the C=O electrons up onto the oxygen. 2) With a carbocation on the beta carbon, the nucleophile simply attacks the beta carbon directly. Starting with either resonance form, the oxygen will get protonated to form an alcohol. Note that the protonated oxygen is really just the enol form of a keto-enol tautomer.

Amines

An amine is any organic compound that contains a basic nitrogen atom Can act as either a base or a nucleophile: --normally with primary or secondary amines acting as nucleophiles --tertiary acting as a base. Amine Basicity: ---Decreases from tertiary to primary to ammonia due to EDG effects of R-groups --- Tertiary amines are less basic then primary amines, slightly more basic than ammonia --- 3 R groups on tertiary amines create steric hindrance, interferes with abstraction of proton by nitrogen and ability of water to solvate and stabilize protonated amine --- SEconadry amines are more basic than primary amines --- Aromatic amines are less basic than standard amines Amines are capable of hydrogen bonding - Weaker than OH due to OH having greater electronegativity...

Electron Withdrawing Groups

An electron withdrawing group or EWG draws electrons away from a reaction center. Makes it less nucleophilic When this center is an electron rich carbanion or an alkoxide anion, the presence of the electron-withdrawing substituent has a stabilizing effect Nitro groups, cyano groups, sulphano groups, carbocylic acids, esters (unless attached to Oxygen of an OR, then EDG), quanterary amines,

Electron Withdrawing Group

An electron withdrawing group will make the carbonyl better at stabilizing the conjugate base and therefore the strongest electron withdrawing group would indicate the strongest acid (because it produces the most stable conjugate base). 1) closer the EWG is to acidic hydrogen, stronger the acid will be (more stable) 2) more electronegative the EWG the stronger the acid 3) more EWGs means stronger acid

Carboxylic Acids

Any compound with a carbonyl containg a hydroxyl substituent on the carbon Nomenclature for Carboxylic acids: --end with an "-oic Acid" -- When loses proton, it has an "-ate" ending, ex- formic acid-> formate Common names: HCOOH- Formic acid, CH₃COOH- Acetic Acid, C₆H₅COOH- Benzoic Acid Very high boiling points due to ability to form dimers involving two hydrogen bonds Without long alkyl chains, they are soluble in water and short chain carboxylic acids are soluble in non-polar solvents due to having no net dipole moment Key features: 1) Resonance Stabilization: Very stable due to this 2) Induction- Look at Alpha substituents, they can either donate or withdraw from carboxylate ion, to increase or decrease acidity, -- Remember: To predict acidity, examine STaBILITY of the conjugate base, if more stable, then it is more acidic 3) Hydrogen bonding: DUE TO HYDROGEN BOND, AND DIMER! (LOOK AT PICTURE)

Systems not in Equilibrium

Any problem where there is a net force, non-zero acceleration Solve same way as equilibrium problems, but add "ma" to losing side. Since there is an acceleration we know that the net forces acting from either side are not equal. That combined net force is what causes the object to accelerate. By adding ma to the weaker side we are making them equal again. The imbalance in forces causes the mass to experience an acceleration. Of course, you could solve by summing all forces to the net force, then substitute ma for that net force. you must carefully track signs. example- If looking for a upward force F (down) = F (up) + ma

Alcohols

Any species with -PH funcitonal group Can act as nucleophiles or as lewis acidwhen oxidized to a carbonyl group Nomenclature- Alcohols have -ol suffix, butanol, cycloheanol, 1,3-hexanediol Boiling Point- Goes up with increasing molecular weight and decreases with increased branching Melting Point- Goes up with polarity and H-bonding and the effect of branching on melting point depends

Dipole Moment

Any time charge is not evenly distributed within a bond (i.e., when the two atoms have non-identical electronegativities) that bond will have a dipole moment q= charge and r= distance between charges Molecules with two or more dipole moments can still have no NET dipole when their geometric orientation causes the dipole moments to cancel each other out example- CO2 the oxygens cancel each other out, while CO has the oxygen pulling on the carbon

Aromaticity:

Aromatic compounds are conjugated, unsaturated ring systems that exhibit greater stability than one would expect based on either resonance or conjugation alone. For example, benzene shows far greater stability than other unsaturated compounds with three double bonds and two resonance forms. Conjugated systems are always very stable, but benzene is far more stable than a conjugated straight-chain alkene. Hückel's Rule: To exhibit aromaticity, a ring system must have exactly 4n + 2 pi electrons.

Titration Curves: Weak Acid with Strong Base

As with the strong acid titration, this one will start at a pH below 7, but since the weak acid only partially dissociates, the pH will be higher than it is for a strong acid, or usually around 3 to 5. For WA w/ SB: pH > 7 As strong base is added, the pH will increase slowly through the buffer region and then go vertical at the equivalence point. The equivalence point won't cover as many pH units as it did for the strong acid titration and leading up to it and after it, the pH will more quickly rise than it did for the strong acid. The half way pH of the equivalence point will not be 7 as it is for a strong acid, it will be higher than 7. This is because the conjugate base of the weak acid is now present, creating a basic solution. After the equivalence point, the pH will slowly rise as more base is added.

Absolute COnfiguration

Assign priority to all four substituents based on molecular weight, with higher molecular weight atoms receiving higher priority. Rotate the lowest priority substituent to the back (i.e., into the page). If proceeding in order from one to three requires a clockwise motion, the absolute configuration is R; If the smallest atom is coming out of the page, you reverse it, so ex- if it is R, but smallest atom is out of the page at 4, reverse it to S, and i'll be correct. If proceeding in order from one to three requires a counter-clockwise motion, the absolute configuration is S. Remember how things change if the heaviest is into the page, it is always the reverse The lowest priority R group is pointed away from you. You then consider the priority of the other three R groups. If that priority descends in a clockwise fashion, the molecule is R. If it descends counterclockwise, then the chiral center is S.

Turbulence

At low velocities real fluids exhibit laminar flow. As velocity increases, and especially for non-viscous fluids, flow becomes turbulent—meaning that although the net flow is still in one direction, there are random eddies, changes in direction, changes in velocity, and so forth.

Terminal Velocity

At terminal velocity, mg = Fair. At terminal velocity, the object has stopped accelerating; the forces of gravity and air resistance are now balanced. OBJECT HAS STOPPED ACCELERATING Where there is air resistance, more massive objects fall faster than less massive objects. Why? Because the amount of air resistance depends upon the speed of the object. A falling object will continue to accelerate to higher speeds until they encounter an amount of air resistance that is equal to their weight. A heavier object will accelerate to higher speeds before reaching a terminal velocity. THus more massive objects fall faster than less massive objects because they are acted upon by a larger force of gravity. For this reason, they accelerate to higher speeds until the air resistance force equals the gravity force. This is why lighter objects initially accelerate slower than heavier objects, because they can reach terminal velocity faster than heavier objects. Larger surface area reaches terminal velocity faster

What increases or decreases as you go across a period or down a group of the period table

Atomic size decreases going across the table or up any column. Fluorine is the smallest atom, except for hydrogen and helium (the noble gases are actually larger in size than the group 7A elements). From this we can intuit anything Electron Affinity: greatest for the smallest atom and least for the largest atom. Electronegativity: greatest for the smallest atom and least for the largest atom. Ionization Energy: very small for a very large atom and larger for a smaller atom Atomic Radius: Atomic size decreases going across the table or up any column Metallic Character: Metallic character will increase with the size of the atom do NOT want students to memorize these trends. ONLY to learn the patterns for changes in atomic radius and then use intuition to quickly determine the pattern for whatever characteristic they are evaluating.

Bernoulli's Equation

Bernoulli's Equation demonstrates the Law of Conservation of Energy: the random vibrational energy of the fluid molecules is given by P (a.k.a. "Pressure Energy"); the gravitational potential energy per volume of the fluid is given by Graviational PE where h is height, not depth; and the kinetic energy per volume of moving fluid molecules is given by KE equation. Within a horizontal flow of fluid, points of higher fluid speed will have less pressure than points of slower fluid speed. So within a horizontal water pipe that changes diameter, regiosn where the water is moving fast will be under less pressure than regions where the water is moving slow. The sum of these three forms of energy in an ideal fluid is always equal to a constant (K). Energy is transferred from one form to the other, but the sum of the components will never change. The MCAT has applied Bernoulli's equation to many different fluids, including air (even though, technically, Bernoulli's assumes an incompressible fluid). Remember that both gases and liquids are fluids!

Cations vs Anions

Cation- atom with fewer electrons than protons Anion- Any atom that has more electrons than protons Metals form Cations but non metals form anions Cations are smaller than their neutral counterpart and anions are larger than their neutral counterpart This size difference between anions, cations, and neutral atoms is due to the following: Cations are smaller because the relative charge in the electron cloud and nucleus increase by 1 unit, causing the electron cloud to suck in. Another reason on the differences in size is due to the fact that most cations form due to losing electrons to match electron configuration of nearest noble glass. This means they lose an entire shell and therefore volume. Anions are larger because those additional electrons take up additional space in the electron cloud, and repel one another, thus making electrons larger.

Covalent vs. Ionic:

Covalent: formed between two non-metals and involve sharing of electrons within the bond. This sharing need not be equal, and is in fact usually not due to differences in electronegativity. ex- HCl, CO2 Ionic: Ionic bonds are usually formed a between a metal and a non-metal and are due to an electrostatic attraction ex- NaCl, cation + anion, solid at room tempreature They can be conceptualized in two ways. First, you can visualize the two species as previously formed ions. For example, Na+ and Cl-. It is fairly obvious that these two species will be strongly attracted to one another by an electrostatic force. Alternatively, you can also visualize it as if the two atoms came together in their ground states (not as ions) and the more electronegative atom (Clin this case) pulled one electron completely away from sodium. This would result in essentially the same result, a sodium cation and a chloride anion

Calorimeters

Device used to calculate enthalpy change (∆H). We are assuming that q (which is what the calorimeter actually measures) is equal to ∆H. This is true at constant pressure. The assumption behind the science of calorimetry is that the energy gained or lost by the water is equal to the energy lost or gained by the object under study. So if an attempt is being made to determine the specific heat of fusion of ice using a coffee cup calorimeter, then the assumption is that the energy gained by the ice when melting is equal to the energy lost by the surrounding water. It is assumed that there is a heat exchange between the ice and the water in the cup and that no other objects are involved in the heat exchanged. This statement could be placed in equation form as Qice = - Qsurroundings = -Qcalorimeter which in essense is the following: q=∆H Coffee Cup Calorimeter: use q=mc∆T Bomb Calorimeter: Solve using: q = C∆T. This does NOT give enthalpy, but change in internal energy, ∆U or ∆E. Use heat capacity (big C) instead of specific heat capacity (little c). -

Titrations

Drop by drop mixing of an acid and a base with an indicator Titrant vs Anylate One "equivalent" = the amount of acid or base necessary to produce or consume one mole of [H+] ions. Pay special attention to where the titration curve starts. Strong acids titrated with anything (strong or weak base) should start low on the y-axis Strong bases titrated with anything should start high on the y-axis. The end of the titration curve should correlate with the pH of the titrant. For example, if you're titrating with a strong base, near the end of the titration the curve should flatten out at a point high on the y-axis. If titrating with a weak base, however, the curve should end much lower due to the base not being as basic as the strong base

Ohm's Law

V=IR V= Voltage I- Current R= Resistance First, remember it CANNOT be said that if V increases, and current remains constant, resistance will increase. This is not true. The correct terminology is that increasing voltage will increase resistance IF and ONLY current remains constant. This is like saying that increasing force while acceleration is held constant will increase mass

Electronegativity

Electronegativity can be understood as a chemical property describing an atom's ability to attract and bind with electrons From left to right across a period of elements, electronegativity increases. If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one. Electronegativity measures an atom's tendency to attract and form bonds with electrons. This property exists due to the electronic configuration of atoms. . Because elements on the left side of the periodic table have less than a half-full valence shell, the energy required to gain electrons is significantly higher compared with the energy required to lose electrons. As a result, the elements on the left side of the periodic table generally lose electrons when forming bonds. Conversely, elements on the right side of the periodic table are more energy-efficient in gaining electrons to create a complete valence shell of 8 electrons. The nature of electronegativity is effectively described thus: the more inclined an atom is to gain electrons, the more likely that atom will pull electrons toward itself.

Electrophilicity

Electrophiles are always electron poor they will ALWAYS have a full or partial positive charge Always attacked by electron rnich species

Empirical vs Molecular Formula

Empirical formulas represent the lowest possible number of moles of each element that can be present in a compound while still maintaining the same mole-to-mole ratio between the elements. A molecular compound is the actual number of moles of each element found in a specific compound. For example, CH2O is the empirical formula for glucose, and C6H12O6 is the molecular formula for glucose. However, CH2O is also the empirical formula for all other carbohydrates. The subscripts for a molecular formula and its empirical formula will always differ by a factor of some whole integer. The two formulas can be the same. For example, the empirical formula for water is also the molecular formula.

Rotation of Plane-Polarized Light

Enantiomers rotate plane-polarized light. R and S enantiomers rotate this light to the same degree but in opposite directions. R enantiomers can rotate this light in a clockwise or counterclockwise direction, as can S enantiomers. If a compound rotates light clockwise it is called (+) or d (dextrorotary) If a compound rotates light counterclockwise = (-) or l (levorotary) However, if you know one enantiomer is dextrorotary, then the other enantiomer must be levorotary.

UV Spectroscopy

Energy difference between 2 adjacent molecular orbitals, is the amount of energy created by electromagnetic radiation in UV spectrum When a molecule is exposed to UV radiation, electrons within that molecule will often absorb that energy and excite to the next highest level Absorbance is recorded on a UV spectrum Focus on these: - Molecules containing only single bonds show low or no UV absorbance - Double and triple absorb UV strong (double<triple) -Conjugated systems absorb UV even more strongly than do isolated double or triple bonds -UV spectrum is a X-axis absorbance vs Y axis wavelength (NM) ---The greater the degree of conjugation, the farther to the right the species will absorb Greater bond strength results in higher absorption of energy

The Law of Conservation of Energy

Energy in an isolated System is always conserved If you add up all possible forms of energy in a system (Internal energy, Kinetic energy, all forms of PE, heat, etc), the total will always remain constant Energy is transferred back and forth between forms, but never lost Open System- Both mass and energy can be exchanged with surroundings Closed System- ENERGY, not mass, can be exchanged Isolated System- Neither MASS nor ENERGY cannot be exchanged

Forming and Breaking Bonds

Energy is released when bond is formed and is required when bond is broken Heat of Combustion: When molecules are combusted, all of the bonds are broken and then reformed via a radical reaction. The less stable the bond, the greater will be the heat of combustion. The more stable the bond, the lower the heat of combustion. That is the key to understanding why less stable molecules release more energy: the energy of the products is always going to be the same (i.e., the energy of CO2 + H2O). Therefore, the higher the energy of the reactant the greater will be the difference in energy between the reactant and the combustion products

First Law of Thermodynamics

Energy neither be created nor destroyed IMPORTANT NOTE: By convention, work done on the system is positive, work done by the system is negative (chemistry definition); o Two Common Ways to Define the First Law of Thermodynamics: 1) The total energy of an isolated system is always constant-An isolated system is a system for which neither mass nor energy can be exchanged with the surroundings 2) The energy change in a closed system is equal to the heat absorbed by that system plus any work done on that system by its surroundings.- A closed system is a system that can exchange energy with its surroundings but not mass. Definitions1 and or 2 are essentially saying the same thing: in definition 2, the surroundings and the closed system are considered an isolated system. Therefore, heat or work can be transferred back and forth between parts of the system and the total energy of the entire isolated system would not change. To further illustrate, let's say that 10J of heat were transferred to the system and 10J of work were also done on the system by the surroundings. -Any work or heat that goes into or out of a system changes the internal energy. However, since energy is never created nor destroyed (thus, the first law of thermodynamics), the change in internal energy always equals zero. If energy is lost by the system, then it is absorbed by the surroundings. If energy is absorbed into a system, then that energy was released by the surroundings: ∆E = q + w

Vacuum Filtration

Vacuum filtration is performed with a Hirsch or Buchner funnel. A vacuum is created inside of the flask which creates suction to pull the filtrate through the filter paper. The filter usually has holes in it which are covered by the filter paper. The primary advantage is that it is faster than gravity filtration.

Enthalpy ΔH

Enthalpy = the energy contained within chemical bonds we can calculate ∆H for a reaction (i.e., the change in enthalpy) by finding the difference in total bond energy between the products and the reactants Enthalpy is a state function which depends entirely on the state functions T, P, U. U is internal energy, T is temperature, P is pressure. If temperature and pressure remain constant, enthalpy is given in this state: ΔH=ΔU+PΔV MUST BE DONE AT A CONSTANT PRESSURE The units of Enthalpy is done in Joules Standard State: A set of specific conditions chosen as the reference point for measuring and reporting enthalpy, entropy, and Gibbs free energy Elements in their standard state have ∆Hformation° = zero. -This is because elements in their standard state are used to define the enthalpy scale and thus there is no change in energy to create them from themselves. Do NOT confuse standard state with STP

Constant Electric Fields

Equates to assumed gravity or gravity near earth constant and its strength does not vary with distance MCAT often uses variable d for distance when talking about constant or uniform electric fields A constant electric field exists between the two plates of a parallel plate capacitor If there are perpindicular lines, then it ISN'T constant

Equilibrium

Equilibrium is the state reached in the progress of a reversible reaction wherein there ceases to be any additional NET progress in either the forward or reverse direction. The reaction is still proceeding to a very small degree in both directions, but these movements cancel one another out Equilibirum is the rate going in the forward direction is the equal in the rate going backwards, but this doesn't mean the concentrations are the same, it just means concentrations wont' change anymore When a chemical reaction has attained the equilibrium state, the concentrations of reactants and products remain constant over time, and there are no visible changes in the system. However, there is much activity at the molecular level as the reactant molecules continue to form product molecules while product molecules react to yield reactant molecules. Chemical equilibrium is achieved when the rates of the forward and reverse reaction are equal and the concentrations of the reactants and products remain constant Under those exact conditions the entropy for that reaction is at its maximum possible value. Those conditions are also the lowest possible energy state for that reaction. Gibbs Free Energy will be exactly zero at equilibrium. This makes complete sense because the reaction would not proceed spontaneously in either direction because it is already at its most favorable state Students frequently confuse equilibrium with rate. For many students it seems intuitive (BUT IS ABSOLUTELY WRONG) that if a reaction has a large Keq this means the reaction "really wants" to reach equilibrium and will therefore proceed toward it quickly. You should be drilling into your students the conviction that equilibrium and reaction rate describe totally different things. Many reactions have high Keq values, but proceed very, very slowly. A high number for Keq simply tells us that at equilibrium there will be a lot more products than there are reactants. This tells us the reaction is spontaneous and will strongly favor the products side of the reaction, but tells us nothing about how fast it will get there. 1) At equilibrium, the rate of the forward reaction is equal to the rate of the backward reaction. 2) Since both reactions take place at the same rate, the relative amounts of the reactants and products present at equilibrium will not change with time. 3) The equilibrium is dynamic, i.e., the reactions do not cease. Both the forward and reverse reactions continue to take place, although at equal rates. 4) A catalyst does not alter the position of equilibrium. It accelerates both the forward and backward reactions to the same extent and so the state of

Titration of a WA w/ SB or WB w/ SA:

Equivalence Point/Stoichiometric Point = midpoint of the nearly vertical section of the graph at this point [titrant] = [analyte] However, because the acid and base are not both "strong" (i.e., dissociate 100% in water) the [H+] does NOT equal [OH-]. This also tells us that the pH does NOT equal 7 An MCAT question will simply ask: "What is the pH of the solution at the equivalence point?" or an answer choice will say "The concentration of hydroxide ions equals the concentration of hydrogen ions at point B." You will need to remember that the first thing you must do on such a question is decide which type of titration is being performed. For WB w/ SA: pH < 7 For WA w/ SB: pH > 7 For SA w/ SB: pH = 7

Quantum Mechanics

Every electron in an atom has a unique "address" or "location." Electron addresses consist of four numbers. One could think of the first number as giving the street name (i.e., shell), the second as giving the house or apartment (i.e., subshell), and the third as giving the room within that apartment (i.e., orbital). Electrons can come in pairs, with two electrons sharing one orbital. They are like two siblings sharing the same room. They are differentiated by their "spin." Quantum numbers 1, 2, 3, and 4 n, orbitals, # electrons in orbital, #electrons in shell so n=1, then ℓ=0, which there is 1 s orbital, and mℓ=0, and the fourth quantum number there are 2 max electrosn in 1s, and 2 electrons in the shell (2n^2) If n=2, ℓ=0,1 thus have 1 s orbital, mℓ= -1,0,+1, thus 3 different orientations, 3 different p orbitals, 2 electrons in 1s, and 6 electrons in 3p orbitals, and thus (2*2^2)=8 electrons in the shell n=3, ℓ=0,1,2, thus 1s, 3p, and 5d orbitals, mℓ= -2,-1,0,+1,+2=5 d orbitals, thus we have 18 electrons

Electric Fields

Field= An invisible influence that can exert a force on a mass or charge Field Lines: Always draw with tails at (+) charge pointing away or pointing toward (-) charge. --- Closer lines represents a strong field --- Looser lines represent weak field Field lines should always be drawn with their tails toward the positive charge and their heads toward the negative charge. Current is said to flow from positive to negative, so it could be compared to the orientation of field lines. Electron flow, however, goes from a high concentration of electrons (negative charge) to a low concentration of electrons (positive charge)—or the exact opposite orientation. E= F/q or E= Newtons/coloumbs F=qE for a F charge in a field

Q34. For a reaction with two reactants, A and B, a graph of ln[A] vs. time is linear. How many of the following statements are true? 1) Reactant A must be first order, 2) Reactant B could be first order, 3) Reactant B cannot be impacting rate, 4) Reactant B must be in excess.

Getting a positive result (i.e., a line for one of the graphs) gives us much more information. Because the graph of ln[A] is linear we know that statement 1 is true, reactant A is indeed first order. We also know, however, that no other reactants are impacting rate. Statement 2 is NOT known. Reactant B could be first order; however, if it is first order then we know it MUST be in excess because only reactant A is impacting rate. Reactant B could also not be first order. It could be zero order and not impacting rate at all—an alternative explanation for why only reactant A is impacting rate. Statement 3 is known for this exact moment and set of conditions. Reactant B cannot be impacting the rate; if it were, the graph of ln[A] would not have been linear. Statement 4 is NOT known but could be true. We know that reactant B is not impacting rate, but that could be either because it is in excess or because it is zero order.

Ideal Gas Law Assumptions

Focus on Following ideal conditions for the MCAT: 1) Gas molecules themselves are of negligible volume compared to the volume occupied by the gas. 2) All inter-molecular forces between gas molecules are negligible. Focus on the first two assumptions; they are responsible for most of the differences between what PV = nRT predicts, and how real gases actually behave. • To simplify things even further: THINK OF IDEAL GAS MOLECULES AS HAVING NO volume and NO inter molecular forces! Other Ideal Gas Assumptions: 3) All collisions between gas molecules are perfectly elastic 4) Gases are made up of a large number of molecules that are very far apart from one another 5) Pressure is due to collisions between gas molecules and the walls of the container 6) All molecular motion is random 7) All molecular motion follows Newton's laws of motion 8) The average kinetic energy (KE) of gas molecules is proportional to temperature --- types of gases don't matter, all gas in terms of ideal gas behavior are indistinguishable, ex- Cl2 same V has H2 gas --- # of moles of gas is the only measurement of molecules themselves we consider --- Gas molecules do not dissipate energy because of the assumption that all of their collisions— whether with each other or with the walls of the container—are perfectly elastic. As we recall from Physics 2, energy is conserved in a perfectly elastic collision.

Heating curve of water

For a heating curve of water the phase change from solid to liquid should be shorter than the phase change from liquid to gas. This is because to change phases from solid to liquid only some of the intermolecular forces must be broken. Recall that hydrogen-bonding (the strongest type of intermolecular attraction) is prevalent in liquid water. In order to change phase from liquid to gas, all of these intermolecular hydrogen bonds must be completely broken (because no intermolecular forces exist between molecules in water vapor)

Voltage (gravity)

For gravity near earth: V = gh -For constant E-field: V = Ed (d is distance change going against the field, measured against E) • For real gravity: V = -Gm/r --- For point charge E-field: V = Kq/r

Far vs Near

For objects that are far away, assume the light rays hitting the lens are all parallel. Considering converging lenses now, the rays will be focused to the focal point a distance f away from the lens. As the object approaches the lens, however, the image will no longer be exactly at the focal point f. Parallel rays will all converge to the focal point. That's the definition of the focal point (see the left figure below). If the object is closer to the lens, the rays will not be able to bend enough to converge at the same spot. They will converge, or "focus" at a spot farther away. That is the image location, not the focal point.

Plane Mirror

For plane mirrors only, the image and the object will always be equal distances on either side of the mirror.

Carbonyl Functional Group

For the MCAT, you can treat most carbonyl analogues, such as S=O or N=O, as you would carbonyls. However, it is quite possible that the MCAT would require you to use your basic knowledge of electronegativity, bond polarity, atomic radius, etc., to predict difference in reactivity between an analogue and a carbonyl. Properties: The carbonyl double bond is shorter and stronger than an alkene because Comparing to two carbons, a carbon and an oxygen can get closer to one another because oxygen has a smaller atomic radius. This allows for more pi overlap and therefore a stronger bond. Key Features of Carbonyls: 1) Partial positive charge on the carbonyl carbon: This makes the carbon a good electrophile. 2) Alpha hydrogens: Hydrogens on the alpha carbon are surprisingly acidic—especially given that alkane hydrogens normally CANNOT be removed. 3) Electron donating/withdrawing groups: The reactivity of a carbonyl with a nucleophile is dramatically affected by the presence of electron donating or electron withdrawing groups on the carbonyl carbon. Donating groups decrease the reactivity of the carbonyl carbon and withdrawing groups increase its reactivity. 4) Steric hindrance: Bulky substituents attached to the carbonyl carbon decrease its reactivity. 5) Planar stereochemistry: The sp2 hybridized carbonyl carbon is planar and can therefore be attacked from either side. When the two substituents on the carbonyl carbon are NOT identical, an addition reaction could therefore create both R and S enantiomers in a racemic mixture.

Manipulating Equations

For the purposes of manipulating equations and seeing relationships between variables only, know these three equations: 1) X = (½)at^2 2) V = √(2gh) [Which can also be written V = √(2ax)]. This is the only equation we'll allow you to plug and chug. Use it when asked for final velocity, given drop height. You can also use it as a stepping stone to find the final velocity. Once you know final velocity, you can intuit all other parameters of the motion using the same conceptual steps given previously. 3) tair= 2V/g (Used only to calculate "round trip" times, or in other words, the total time in the air. The variable V must be the vertical component of initial velocity).

Force

Force = any influence capable of causing a mass to accelerate Examples of Force: The force due to gravity, contact forces, electrostatic forces, torque (a force at a distance from a point of rotation), tension, magnetic forces, etc Forces are vectors and can thus sum to zero. This is called "no net force" and is the same as if no force existed at all. If one of those forces is suddenly changed, a net force is instantly created. o Measured in Newtons F=ma ( mass X acceleration)

Newton's Second Law-

Force equals Mass times acceleration Whenever force, mass, or acceleration are asked for, first try to solve using Fnet = ma. First, a constant force will NOT cause an object to accelerate faster and faster; it will cause a constant (non-changing) acceleration. Only a changing force can cause a changing acceleration. That being said, a constant force can cause an object to move faster and faster—in which case the displacement is changing non-linearly, the velocity is changing linearly, and the acceleration is not changing at all (i.e., it is constant)-- A related misconception is that a constant force applied to an object will cause it to travel at a constant velocity. This is absolutely NOT true. A constant net force will always cause a constant acceleration—and therefore a changing velocity. Rehash these relationships until they are perfectly clear in your mind. Second, you CANNOT accelerate a ball horizontally across the room by throwing it-- To accelerate, an object must be either 1) in contact with the object creating the force, or 2) be under the influence of a field force (e.g., gravitational or electrical) at that exact moment. Thus, the ball only accelerates horizontally during the brief time it is in contact with the object creating the horizontal force—in this case, your hand. In the vertical direction the ball is always accelerating (after it leaves your hand) because it is always under the influence of earth's gravitational field. -aka Acceleration occurs when in contact with an object creating a force or under influence of a field force - this is why horizontal force is constant after thrown or launched from hand - There is influence in vertical direction due to gravity

F = qvBsin(theta)

Force exerted on a charged particle moving in a magnetic field theta= angle between v and B - perpindicular -Parallel has NO FORCE Units of B= N*s/C*m or Kg/A*s^2=Tesla The charged particles must move within the magnetic field for any force to be created;

Acetoacetic Ester Synthesis

Formation of a ketone from a β-keto ester. o STEPS: 1) A base abstracts the acidic alpha hydrogen, leaving a carbanion. 2) The carbanion attacks an alkyl halide (R-X), resulting in addition of the -R group to the alpha carbon. 3) Hot acid during workup causes loss of the entire -COOR group

Synthesis of an Alkane from an Alkene:

Formed from alkenes through rxn with H2 with metal catalyst Syn addition- H2 added to same side anti- new bonds formed on opposite sides CH2=CH2 + H2/Pd(catalyst) -> CH3CH3

Universal Law of Gravitation

Formula: F = Gm1m2/r2 G is the universal gravitational constant r is distance between 2 objects The m1 and m2 are masses F is force The Universal Law of Gravitation is true everywhere. Near earth, however, we make an assumption that gravity is a constant 10 m/s2, despite the fact that this law shows that gravity actually varies ever so slightly with height. Based on the near-earth assumption, we can simplify the equation to: F = mg

Harmonics

Frequency of the first harmonic is called the fundamental frequency, all the harmonics after have its own unique f and λ f of ANY harmonic is = to n X (fundamental f) --- n= harmonic number --- FUNDAMENTAL f, first frequency Each harmonic has one more node and one more anti node than the previous harmonic The distance between any two adjacent nodes will be one-half of a wavelength. The distance from node 1 to node 3 will be one wavelength. The distance from node 1 to node 4 will be 3/2 of a wavelength. Overtones For oscillators with MATCHING ends, the wavelength λ of the 2nd harmonic - the length of the string or pipe ---- λ=L

Inorganic Nomenclature

General Ionic Compunds: Name the cation first, then the anion (i.e., calcium sulfate is CaSO4, not SO4Ca, and is not called "sulfate calcium") Transition Metals: When written in words, compounds that include transition elements must have a roman numeral showing the oxidation state of the metal (e.g., iron(II)sulfate vs. iron(III)sulfate) Monatomic Ions: Named by replacing the last syllable with "-ide." (e.g., sulfide ion, hydride ion, chloride ion, etc. Acids: Follow the "ate-ic - ite-ous" convention. If the ion name ends in "-ate," replace that ending with "-ic" as in: Nitrate Nitric Acid. If the ion name ends in "-ite," replace that ending with "-ous" as in: Nitrite Nitrous Acid. If the parent is a single ion rather than a polyatomic ion, replace the "ide" ending with "-ic" and add "Hydro-" as a prefix, as in: Iodide Hydroiodic Acid. Binary Compounds: Name the element furthest down and to the left on the periodic table first; use poly prefixes as necessary (e.g., Nitrogen Trioxide, Carbon Monoxide, Sulfur Dioxide, etc.). Some have common names such as ammonia and water.

Fluid Pressure

General Pressure- P = F/A Atmospheric pressure is the fluid pressure due to the earth's atmosphere at that location. You could conceptualize it as the weight of the column of air above that point—explaining why atmospheric pressure decreases with increased elevation. Fluid pressure is the force per unit area at some point within a fluid. Therefore, atmospheric pressure is really just a type of fluid pressure wherein air is the fluid. If we examine common usage, however, when people refer to "fluid pressure" they are usually referring to the pressure at some depth within a liquid. Gauge pressure is measured with respect to atmospheric pressure, where atmospheric pressure is defined as zero gauge pressure. Put another way, gauge pressure is the amount of pressure in excess of the ambient atmospheric pressure. The absolute pressure would be the actual total pressure of the atmosphere, plus gauge pressure. An example most students are familiar with would be tire pressure. If your tire had a pressure of 1 atm at sea level, it would appear to you to have no pressure whatsoever. However, it clearly has some pressure—it is just the same pressure as the air around you. When you inflate the tire to 35 psi, you are really inflating it to 35 psi ABOVE atmospheric pressure. Atmospheric pressure is about 15 psi at sea level, so the actual total pressure is 50 psi. It is the gauge pressure that is 35 psi.

PE=mgh

Gravitational Potential energy is the energy stored in an object as the result of it's vertical position or height. Thus the variable of h is necessary to know the PE. More massive objects have greater gravitational PE.

Gravity

Gravity is a field that exists between any two objects with mass. Field = an invisible influence capable of exerting a force on a mass or charge Objects pick up speed at the same rate regardless of weight when gravity is the ONLY force. When there is air resistance, then there is different speeds. Free fall can only occur where there is no air, thus gravity is the only force acting, thus mass don't matter. Vf=g X t: determines velocity d=.5 X g X t^2: distance fallen after a time of t seconds given in a formula

Grignard Synthesis

Grignard Synthesis: Production of an alcohol with extension of the carbon chain KNOW MECHANISM o CH3COCH3 + CH3MgBr -> CH3COH(CH3)2 Use H3O+ to protonate the O atom Produces an alcohol by adding RMgX (most frequently RMgBr; called an organometallic compound) to a carbonyl. Results in an increase in the number of carbons. The Grignard Reaction will also work with other electrophilic double bonds such as C=N, cyano groups, S=O and N=O STEPS: 1) Due to the very low electronegativity of Mg, the R group in RMgBr gains significant electron density and more or less acts as if it were a carbanion (R:- ), attacking the electrophilic carbonyl carbon. This occurs in a single step, kicking the electrons in the C=O bond up onto the oxygen. 2) The negatively charged oxygen is protonated, yielding an alcohol. https://www.khanacademy.org/science/organic-chemistry/alcohols-ethers-epoxides-sulfides/synthesis-alcohols-tutorial/v/synthesis-of-alcohols-using-grignard-reagents-ii

Energy of a Photon

H= Plank's constant= 6.62607 X 10^-34 Js You can combine the formula E = hf with the wave speed formula c = fλ (c = the speed of light) to obtain E = hc/λ. Since h and c are constants, this allows you to calculate the energy of a photon knowing only its wavelength. The MCAT has presented multiple problems that would require this approach.

Acid Dissociation

HA + H2O <->H3O+ + A- (H3O+ is the same as H+) Ka = [H+][A-]/[HA]

Bicarbonate

HCO3-

Electron Flow

HIgh to low concentration in rxns, so form a full or partial negative charge to a species with a full or partial positive charge. Bases and Nucleophiles attack electron poor species called electrophiles For the MCAT focus on the function: if a species abstracts a proton it is acting as a base and if it attacks a carbon it is acting as a nucleophile. Most students could simply benefit from seeing and being more familiar with each of the above classes so they begin to get a better intuition for each functional group.

Nitric Acid

HNO₃

halogens

Halogens are the group 7A elements just to the left of the noble gases

Simple Distillation

Heat mixture in a flask Liquid with lower boiling point evaporates first, enters a collecting arm, cools and drops into a collecting flask Cooling the condensing arm or placing the collecting flask on ice can improve the separation process

(Springs ) Hooke's Law

Hooke's Law: Springs, and many other items such as resilient solids, rubber, and even bonds between atoms, follow Hooke's Law. o F = k∆x (where ∆x is the displacement of the spring from its equilibrium point, NOT the overall length of the spring) The law itself states the F, the force needed to extend or compress a strong by distance X, is proportional to that distance, with the spring being a factor. So this means that the amount tha the spring extends is proportional the amount of force with which it pulls. The spring constant k is the ratio of F/x. If this ratio is low, then there is a large displacement for any given F value.

IR Spectroscopy

If a bond that has a dipole, exposing that bond in a external electric field will cause atoms to move within that field like a charged particle attached to a spring, infrared radiation is used to create an oscillating electric field, which in turn causes dipolar bonds to oscillate at a specific vibrational frequency To produce an IR spectrum, the frequency varies the IR radiation. When IR radiation matches frequency of vibration of a particular bond, that bond is said to be in resonance and absorbs some of the IR energy. This absorbance is what is picked up by the detector A BOND WITH NO DIPOLE WILL NOT BE DETECTED BY IR Essentially we are finding the vibration for the specific bond. The vibrational frequency is determined by the strength of the bond and MW of the bonded atoms It correlates to f = (1/2pi) √(k/m). Strong bond- large k, and small bond- small k Strong bond, smaller atom- higher vibration frequency vs large atom, small bonds/ weaker bonds- lower vibrational frequency

Ranking Resonance Structures:

If determining the relative contribution of various resonance structures to the actual structure, the individual structure that contributes the most to the actual structure is the one that: 1) Allows the most atoms to have a full octet (unless atom is a common exception to the octet rule). OCTET rule, octet preferred! 2) Has the least formal charge (i.e., no charge is better than some charge and one formal charge is better than multiple formal charges). The lower the charge, the more stable it is 3) Places formal charge on the atom most receptive to that charge (i.e., it is preferable to have a negative formal charge on oxygen than on carbon because oxygen is more electronegative). o Among similar species that both experience resonance, the more stable specie will be the one with the most possible resonance structures (i.e., ClO4 - is more stable than ClO3 - because perchlorate has four resonance forms and chlorate has only three).

Solving circuits using Ohm's Law: Second

If no simple circuit, use Kirchoff's rules Kirchoff's 1st Rule: total current into a node = total current out of a node Kirchoff's 2nd Rule: in any closed loop circuit, the sum of the voltages equals zero (i.e., the sum of the voltage drops across each resistor equals the total voltage of the battery) Kirchoff's rules will often provide you with the missing piece of information. Then you may need to return to the rules above to finish simplifying your circuit.

Velocity vs time graph

If the acceleration is zero, then the slope is zero, aka a horizontal line If acceleration is positive, then the slope is positive If the acceleration is negative, then the slope is negative A positive velocity means the object is moving in the positive direction and a negative velocity means the object is moving in the negative direction. Negative is below x axis and positive is above the y axis Speeding up vs slowing down- Speeding up means that the magnitude of the velocity is speeding up. Similarly, an object with a velocity changing from -3 m/s to -9 m/s is also speeding up. Either way, the magnitude of the velocity, the number itself, is increasing; thus speed is getting bigger. If the line is getting further away from the x-axis, then the object is speeding up. If the line is approaching the x-axis, then the object is slowing down. Remember using velocity averages to find acceleration

Maximum Static Friction

In cases of static friction, the friction created before an object begins to slide will always remain equal to the net applied force which the friction is opposing. For example, if you push on a boulder with 20 N of force, there will be 20 N of static frictional force opposing you. If you increase the force you apply to 100 N, the static friction will also increase to 100N. This continues up to the "maximum static friction." Once this value is exceeded, the object will begin to slide and we then have a case of kinetic friction, NOT static Q33. 500 N is applied to an object and it does not move. 501 N is applied and it just begins to slide. Describe the amount of force that must be applied to the object continuously to move it at a constant velocity across the surface. --Between the same two surfaces, kinetic friction is always less than static friction. To maintain constant velocity, the applied force must exactly counterbalance the kinetic friction. Therefore, we would expect that some force less than 501N will be required. If the same force of 501N remains on the object, we can predict that it will accelerate

Ionization Energy

Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase. Conceptually, ionization energy is the opposite of electronegativity. The lower this energy is, the more readily the atom becomes a cation. Generally, elements on the right side of the periodic table have a higher ionization energy because their valence shell is nearly filled. Elements on the left side of the periodic table have low ionization energies because of their willingness to lose electrons and become cations. Thus, ionization energy increases from left to right on the periodic table. Another factor that affects ionization energy is electron shielding. Electron shielding describes the ability of an atom's inner electrons to shield its positively-charged nucleus from its valence electrons. When moving to the right of a period, the number of electrons increases and the strength of shielding increases. As a result, it is easier for valence shell electrons to ionize, and thus the ionization energy decreases down a group.

Kinetics

Kinetics is the study of reaction rate. how quickly the reaction proceeds. This is usually measured in terms of how fast the reactants disappear by tracking changes in the concentration of the reactants as a function of time (i.e., Molarity/second ; M/s) think of rate as depending on how fast the reactant molecules are moving (how much KE they have) and the relative height of the Energy of Activation "hill" that they must surmount in order to turn into products. The reactant molecules must also collide with the right orientation to one another. At any given time molecules in the mixture of reactants will have a variety of different energies. Some will have enough to react while others will not. Because temperature is a measure of the average KE of the molecules, increasing temperature will cause a greater fraction of the molecules to have sufficient energy to overcome the barrier and therefore more of them will react. if the reactants have more KE (higher temperature) they will be moving more quickly and collide more often, increasing the probability two reactants will strike one another with the correct orientation needed to react It is IMPERATIVE that students understand that the rate of a reaction is independent of its thermodynamic properties. It is trying to confuse you with the fact that solids and liquids are always left out of the formula for the equilibrium constant (Keq).

Writing Rate Laws:

Know how to write a rate law, how to determine one from a table of experimental values, how to predict experimental results based on a given rate law. Rate laws assume the following: 1) Reactions only proceed forward (we ignore the reverse reaction) 2) We only consider the first few seconds of the reaction, when there is a high concentration of each reactant and any catalysts (e.g., enzymes). o Rate Law Exponents: Students often get the false idea that the exponents in the rate law are given by the coefficients in the balanced equation. The exponents equal the "order" of each reactant. Only if you are specifically told that the reaction is "elementary" do the coefficients equal the exponents in the rate law. For the MCAT, always assume that they do NOT. TEMPERATURE MATTERS, if temprature is given, you can only get a rate law from concentrations that have similar tempreature.

L= = nλ/4 (harmonics)

L= = nλ/4 --- only one node and antinode, pipe open at one end ONLY --- n- 1, 3, 5..... odd numbers ---- Can be rearranged for λ=4L/n For a pipe open at one end and closed at the other, the first harmonic features a node at one end and an antinode at the other. It is impossible to have a node at the open end of a pipe and impossible to have an antinode at the closed end of a pipe. The logical "next step," if you will, to move to the next harmonic from the first one is to add a node—this is impossible, however, because it would require that there be nodes at both ends of the pipe. Thus, we skip this step and add one node and one antinode to get the third harmonic. Notice that this follows the general pattern explained in the lessons that each successive harmonic will have one additional node and one additional antinode. In the case of resonators with mixed ends, however, the "next" harmonic will be the next odd harmonic—or the next possible harmonic given the limitations just described.

Visualize Photons as physical packets of light

Light is physical packets of energy called photons Think of photons as little square packages Visualize one of these packages striking a flat boundary at an angle It is easy to see that one corner of our little light packet is going to hit the surface first, before other corners If the light is passing form a low index medium to a high index medium, that first corner is suddenly going to be forced to go slower than any other part of the packet that is still in the less dense medium, much like when a car tire goes off the road and hits a soft shoulder The light packet will pivot around the corner that is stuck in the higher index medium Without plugging anything into snell's law or memorizing a rule about which scenario causes light to bend toward the normal vs away from the normal, we can intuit exactly which way the light will bend Some of the refraction angles may be exaggerated to make the direction of refraction clear. Students may be surprised by the two scenarios in which the light does not bend back to a line that is parallel with the incident ray. This occurs because the first refraction sends the light onto a surface that is perpendicular to the original interface. The entering and exiting rays will ONLY be parallel to one another if the two interfaces are also parallel to one another. If these cubes had been rectangles tall enough that the refracted ray always hit the opposite side, the normal pattern of parallel entry and exit would have been observed.

Gas Chromatography

Liquid is used as the stationary phase Mixture is dissolved into a heated gas and passed through the liquid Various components reach the exit port at different rates based on 1) boiling point and 2) polarity Only consider polarity if two substances have almost identical boiling points On a gas chromatograph, there will be one peak for each unique compound in the mixture. Also think about how PV=nRT will affect it. If it is at a lower temperature, the gas particles will slow down,thus a better picture of the peak! The height of the peak in a gas chromatograph is relative to the abundance of that component, thus the more there is of X, it will have a bigger peak.

Bascity vs. Nucleopohilicity

Steric Hindrance favors bascitity over Nucleophilicity - Nucleophiles must have VERY little hindrance, -primary nucleophiles most common -secondary atoms can often as as bases or nucleophiles -tertirary atoms will only act as bases Reactivity (low stability) favors bascicity over nucleophilicity - if an atom has a full negative charge it will almost always act as a base (halides are notable exceptions)

Henry's Law

Most important: The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas over that liquid. Primarily used to describe the solubility or partial vapor pressure of gases dissolved in liquids. There can be some confusion here, because Henry's Law is defined in multiple forms; Vapor Partial Pressure of solute = (mole fraction of solute)*(Henry's Law Constant) Vapor Partial Pressure of solute = (concentration of solute)*(Henry's Law Constant) Vapor Partial Pressure of solute = (concentration of solute)/(Henry's Law Constant) You must look up the constant that is specific to 1) the solute involved, and 2) the form of the equation you are using. Because of this complexity and potential for confusion, if Henry's Law shows up on the MCAT they will define it for you and give you the appropriate constant. We recommend you treat this section as background information only and focus on the following principle illustrated by Henry's Law above ↑↑↑

POWER

ONLY THINK OF POWER IN THIS EXACT WAY IN THIS EXACT ORDER 1) P = ∆E/t 2) P = W/t 3) P = Fdcosθ/t 4) Pi = Fvcosθ (P= F * v) Caution- Equation 4 only gives "instantaneous power," it should only be used when you are asked to solve for power USING FORCE AND VELOCITY Units are always in watts= J/s,

F=Gm1m2/r^2

Often referred to as the "inverse square law" because force varies inversely with the square of the distance r. G, the gravitational constant, is 6.67 x 10-11 Nm2/kg2, but this value is usually given.

Reading H-NMR Spectra

Peaks: Each peak represents all of the hydrogens in a molecule that share an indistinguishable chemical enviornment, aka equivalent hydrogens Spin-SPin SPlitting: Presence of neighbors, non equivalent H attached to neighboring carbon, causes splitting of the peak. The peak for a set equivalent hydrogen will be split into exactly "n + 1 sub-peaks" which will assist you in deducing which parts of a molecule are represented by each peak. --- The number of sub peaks tells you how many hydrogens are represented by that peak ( # subpeaks - 1) which will help you find which parts of a molecule are shown by each peak Area under the peak: Relative representation of the number of hydrogen accounted for by that peak. An integral trace make this easier to determine. The relative area under each curve is given by the height of each step. Relative we mean that if one peak is 2 units high and the other is 6 units high, this tells you only the latter is accounted for by 3 times the number of hydrogen, not the first peak accounting for 2 hydrogen and second for 6 hydrogen. Absorbance Range: 0 - 12 ppm; 12 ppm is downfield = deshielded 0 ppm is upfield = shielded; reference comppund TMS as 0 ppm https://www.youtube.com/watch?v=k0eR8YqcA8c

Plane-polarized light

Planepolarized light is light that exists in only a single plane. Normally, light waves are oriented in an infinite number of planes from zero to 360°. A polarizer can sift out all of these leaving, for example, only vertically oriented waves.

Extraction

Purpose: Use to separate two compounds or to remove a desired product from a rxn mixture Two liquids, a polar and non-polar are used. The separation depends on the target molecule having differential solubility in two solvents How it works: --- The two solvents used will ideally have widely different polarities and densities and will have a distinct line of separation --- If target product is already dissolved in a solvent that fits these requirements, it can serve as one of the two immiscible liquids, if not, the mixture containing the target will be added to the separatory funnel along with two other immiscible solvents --- Contents are mixed, thus allowing the solvents to fully separate after sitting --- If target is a polar compound that was synthesized in a non-polar solvent, then the target should easily move into the polar layer during mixing (like dissolves like) --- If the target is a non-polar product, it should readily move into the non-polar solvent --- After the two players are fully separated, the bottom layer is drained out through the stopcock ---- Solvent layer contain the product is then evaporated to obtain the target Like product and solvents attract... polar to polar and non polar to non polar FOR THE MCAT, non polar is less dense and will always be on top and polar is more dense and will always be on the bottom

Flow rate and it's relation to cardiac output

Q = AV Q is flow V is velocity A is area of cross section Area in this equation is always total cross-section area. Therefore, if a large pipe splits into to smaller pipes you must add the cross-sections of both new pipes to get the new area. This formula is often used to describe fluid flow in the cardiovascular system. The variable A is the cross-sectional area of the blood or lymph vessel, and V is velocity. Q is a function of cardiac output. Cardiac output = stroke volume x heart rate Q53. Use the relationship Q = AV to explain how velocity varies as blood flows throughout the human circulatory system (i.e., aorta to arteries to arterioles to capillaries venules to veins to vena cava). - The cross-sectional area of individual vessels decreases as you go from the aorta to the capillaries. However, it is the TOTAL cross-sectional area that we would apply to Q = AV. Total cross-sectional area increases as you go from aorta to capillaries. Because area is greatest at the capillaries, the velocity of blood is lowest at the capillaries. The reverse is true on the return trip: cross-sectional area decreases as we go from capillaries back to the vena cava. Therefore, velocity increases.

Formation of Acid Chlorides

RCOOH + PCl₃ → RCOCl + H₂O Normally use PCl₃, PCl₅, SOCl₂ to form Acid Chloride Remember: Addition of Chloride ion Cl- to a carboxylic acid does NOT produce an acid chloride due to Cl- being already stable on it's own. MOST REACTIVE CARBOXYLIC ACID DERIVATIVES due to: 1) The withdrawing power of the Chlorine 2) Chloride is an awesome leaving group

Esterification

RCOOH + ROH -> RCOOR + H2O Reaction of an alcohol with a carboxylic acid to form an ester. You've probably realized by now that the hydroxyl group will never leave without being protonated first to form the "good leaving group water"; thus this reaction requires an acid catalyst. This is how triacylglycerols are formed: A glycerol undergoes esterification with three fatty acids. o Higher yields can be obtained by reacting an anhydride with an alcohol.

Friction

REMEMBER: Friction opposes sliding, NOT motion Which way does the friction force vector point for a car driving east down a straight road? For a skidding car with locked brakes? For a gecko climbing a wall? For a car driving around a corner? For a car driving east, the friction vector between the road and the tires also points east. The tendency of the tires is to slide past the road, toward the back of the car; and friction opposes that tendency. When a car locks its wheels, however, friction points opposite to the direction of the car's tendency to slide forward. Friction would point up the wall for a gecko, because the gecko's hands would tend to slide down the wall. For a car going around a bend, momentum makes the car continue naturally in a direction tangent to the circle. Friction points toward the center of that circle, keeping it in circular motion

Decibel System

Rating system for intensity of sound within range of human hearing A sound 10 times more intense is 10 decibels higher A sound 100 times more intense is 20 decibels higher a sound 1,000 times more intense is rated as 30 decibels higher Intensity in Decibels = 10*log(I/Io) I= Intensity of sound wave in W/m² Io= Threshold of Human hearing, 1 X 10⁻¹² W/m² example- Sound level suddenly rises form 20 decibels to 60 decibels, how much louder or intense is the sound at the end of this increase? Its 10,000 times more, not 1,000,000, you take the difference remember that each factor of +10 in decibel number is the same as x10 in intensity. Starting at 0 dB = 10-^12 W/m2 , adding +10 to dB gives you 10^-11 W/m2 , adding another +10 gives you 10^-10 W/m2 , adding another +10 gives you 10^-9 W/m2 , and finally adding a fourth +10 to get a total of +40 dB must give you 10^-8 W/m2 .

Galvanic Cells cont.

Reduction always happens at the cathode Oxidation always happens at the anode this ALWAYS happens for ALL electrochemical cells Cathode= + Anode= - This is only for galvanic cells, NOT electrolytic cells Cell Potential is ALWAYS positive for galvanic cells, NOT electrolytic cells A functioning Galvanic cell can be created using ANY two metals, regardless of their reduction potentials: this means that a current will always be produced between two species and the e- flow will occur from the lower reduction potential to the species with higher reduction potential

Four Lens/Mirror Rules

SINGLE LENS SYSTEMS ONLY Keeping track of signs: You MUST use the correct signs for every variable in these lens/mirror formulas or you will get a wrong answer. The rules outlined below will help you determine the sign of f, dI and do. If you get a negative number for the magnification, M, that result simply tells you that the image is inverted. 1) Object distances (do) are ALWAYS (+) 2) Image distances (di) or focal point distances (f) are (+) if they are on the same side as the observer, and (-) if they are on the opposite side from the observer. 3) The observer and the object are on the same side for a mirror, and on opposite sides for a lens (You have to be behind your glasses to see through them!) 4) PRI / NVU: "Positive, Real, Inverted" and "Negative, Virtual, Upright" These two trios of image descriptors always stick together. As long as you can confidently establish that the image has one of those three characteristics, you automatically know the other two!

Bohr Model of An Atom

Size of Components: A nucleus is made up of protons and neutrons held together by a strong residual force. Protons are positively charged, neutrons neutural, and about same size and mass. Electrons are much smaller, to the point that the electron cloud is mostly dead space. Charges: Protons are +, neutrons are neutral, electrons are - orbital filling corresponds to modern electron configuration diagrams—specifically to the number of electrons that can be held in an s, p, d and f orbital: 2, 6, 10 and 14. These numbers also match perfectly with the periodicity seen in the periodic table. Electrons can and do jump from one level to another if they receive the exact quantum of necessary energy and will release a photon equal in energy to the difference between two energy levels when they "relax" back to a lower energy level Electrons have both wave like and particle like nature, similar to light Electrons do not orbit the uncleus in circular patterns like rings Electrons have S, p d, and f orbitals with unique shapes

Solubility vs Solubility Product Constant

Solubility is a measure of "how much" of a solute can be dissolved in a given solute. For example, the solubility of iron(III)chloride in water is 74.4g/100mL The solubility product constant, or Ksp, is defined as the product of the dissolved ions in a saturated solution (i.e., at equilibrium) raised to their coefficients in the balanced equation. Ksp and solubility are directly related to one another (i.e., a large Ksp indicates a large solubility), but are not the same thing. An analogous comparison would be to ask "how much" of a strong acid will dissociate in 100mL of water and then compare that to the Ka of that acid. Because Ksp and solubility are not identical, a ranking of Ksp values for various substances may or may not match the order of a ranking of solubilities for those same substances. As an example, the solubility of NaCl is approximated by the square root of the Ksp (i.e., Ksp = [x][x]), but the solubility of CaCl2 is approximated by the cube root of one fourth of the Ksp (i.e., Ksp = [x][2x]2 = 4x3 ). Finally, the two quantities have different units.

SOlubility

Solute's tendency to dissolve in a solvent The amount of a solute that will dissolve in a given solvent at a given temperature. Temperature is usually specified because for most solids dissolved in liquids, solubility is directly related to temperature. On the MCAT, solubility is usually measured in either g/mL, g/100mL, or mol/L. "Like dissolves like:" This phrase refers to the fact that polar substances are soluble in polar solvents and non-polar substances are soluble in non-polar solvents. Polar and non-polar substances do NOT form solutions.

Bomb Calorimeter

Solve using: q = C∆T. This does NOT give enthalpy, but change in internal energy, ∆U or ∆E. Use heat capacity (big C) instead of specific heat capacity (little c). -utilizies constant volume, The bomb calorimeter is a sealed steel container, meaning volume cannot change. However, because volume is constant any gases produced or consumed during the reaction will change the pressure. bomb calorimeter is used to measure heat flows for gases and high temperature reactions. In a bomb calorimeter, the reaction takes place in a sealed metal container, which is placed in the water in an insulated container. Heat flow from the reaction crosses the walls of the sealed container to the water. The temperature difference of the water is measured, just as it was for a coffee cup calorimeter. Analysis of the heat flow is a bit more complex than it was for the coffee cup calorimeter because the heat flow into the metal parts of the calorimeter must be taken into account

Concentration Cell

Special type of Galvanic Cell A concentration cell is a limited form of a galvanic cell that has two equivalent half-cells of the same composition differing only in concentrations. One can calculate the potential developed by such a cell using the Nernst Equation. Same electrodes and solutions are used in both breaks One beaker, the metal is oxidized via oxidation half reaction Other beaker, it is reduced via reduction half-reaction The beakers use the SAME metals, thus E° cell is always E°cell = 0.00 V. Remember that E°Cell for a concentration cell, will ALWAYS equal 0, because you are using the same species for both the anode and cathode, for the reduction and oxidation half equation Based on this cell potential, it appears that nothing would happen. However, all E° values are given for standard conditions (the reason for the naught symbol). You do NOT need to know those conditions for the MCAT, but one aspect of standard conditions happens to be 1M concentrations for both solutions. Concentration cells are therefore nonstandard conditions by definition. They have a positive reduction potential E (no naught symbol, signifying nonstandard conditions) if there is a difference in the molarities of the two solutions. The Nernst equation is used to calculate the cell potential based off of the E˚ of the species and the concentrations of the two solutions. Yes, you do need to know the Nernst equation—it has shown up on the MCAT at least twice before.

Specific Heat Capacity

Specific Heat Capacity, however, describes energy absorption for one individual substance only and is defined per unit mass. Little "c" is used instead of big "C". The amount of heat needed to increase the temperature of one gram of a substance by one degree is the specific heat capacity Specific heat capacity is SPECIFIC FOR EACH SUBSTANCE! It doesn't change Heat capacity can change c = q/m∆T ; often re-written as: q = mc∆T Specific Heat of Water = 1.0 cal/g˚C or 4.18 J/g˚C

Formation of Acetals/Hemiacetals and Ketals/Hemiketals

Students seem to have a difficult time remembering the structure of these four species and telling them apart. Acetals/ketals have two -OR substituents and hemiacetals/hemiketals have one -OR substituent plus one alcohol substituent (-OH group). The MCAT will sometimes refer to both hemiacetals and acetals as simply "acetals." On other occasions they have differentiated the two. Be aware of both conventions. STEPS: 1) An alcohol acts as the nucleophile, attacking the electrophilic carbonyl carbon and pushing the pi electrons from the C=O bond up onto the oxygen 2) The negatively charged oxygen is protonated to form an alcohol and the original alcohol is deprotonated to form an ether. This yields a hemiacetal if it was originally an aldehyde, or a hemiketal if it was a ketone. 3) The alcohol is protonated again to form the good leaving group water, and a second equivalent of alcohol attacks the central carbon as shown below. 4) Deprotonation of the second alcohol results in another ether, yielding an acetal if it was originally an aldehyde or a ketal if it was a ketone.

Examples of Coordinate Covalent Bonds

Students will see two types of coordinate covalent bonds. The first one is illustrated any time a nucleophile with a lone pair abstracts a proton: NH3 + HCl -> NH4 + Cl- . The amine binds a fourth hydrogen, but the electron belonging to that hydrogen stays with the chlorine. Both electrons that were part of the amine lone pair now form the new covalent bond between nitrogen and the fourth hydrogen. Another example, and the one we've seen most on the MCAT, is easily recognizable. It involves a metal coordinated with one or more molecules that have lone pairs. When you see something like [Fe(NH3)4] 2+ or [Co(NH3)6] 3+ these structures should stand out because they look almost like ionic compounds, but obviously the amine does not have a charge (so they cannot be ionic). This thought would lead one to wonder how the amines are attached to those metals? The answer is via coordinate covalent bonds. A common and very applicable example of coordinate covalent bonds in the human body is the binding of iron in the heme unit of hemoglobin:

Batteries

Symbol: 2 vertical lines of unequal length --- Longer line represents + terminal and shorter line represents - terminal. think of batteries as e- pumps that push e- onto the negative terminal of the battery- meaning it creates a separation of charge and a potential difference between terminals to drive e- flow around the circuit to the + terminal ---- Remember: ANYTHING THAT SEPARATES A CHARGE CREATES A VOLTAGE AND CAN BE THOUGHT OF AS A BATTERY

Resistors

Symbol: zig zag line There is always a voltage drop across any resistor when the current flows through it INTERNAL RESISTANCE: Batteries have internal resistance due to resistivity of internal compnents, resulting in slight voltage drop in terminal voltage of battery Current flow through parallel resistors is always apportioned INVERSELY based upon resistance, EXAMPLE: IF ONE RESISTOR HAS 2X RESISTANCE, it will only receive HALF the current

Le Chatelier's Principle

Systems already at equilibrium, that experience change, will shift to the left or to the right to reduce the effects of that change and re-establish equilibrium. When you disrupt the equilibrium, creating a "shift" according to Le Chatelier's principle, what happens to Keq? Does it change? -Keq doesn't change, the value of equilibirum constant for the rxn does not change. Predict the effects of doing each of the following to a reaction at equilibrium: 1) adding/removing reactants- adding shifts right/ removing shifts left 2) adding/removing products- Adding shifts left, removing shifts right 3) increasing/decreasing pressure- Increasing pressure shift rxn to side with fewer moles of gas, decreasing pressure shift rxn toward side with more moles of gas 4) increasing/decreasing temperature.- Increasing temp changes Keq and shifts the rxn: -exothermic increase temp shift rxn to left and Keq decreases -endothermic rxn increasing temperature, shifts to the right and Keq increase -decreasing temp will have the exact opposite for each.

Constant Volume vs. Constant Pressure Heat Capacities

Systems can be confined by rigid walls (constant volume) or can be open to the atmosphere like water in a beaker (constant pressure Q3. What happens when heat enters a system? Does the temperature always increase? Is any increase in temperature always exactly proportional to the heat absorbed by that system? (Hint: Think of adding energy to a sealed steel container vs. adding energy to a balloon; remember that temperature is the average kinetic energy of the molecules.) PV work is the work necessary to produce an increase in volume. For example, when a sealed balloon is heated, the gases inside the balloon will expand and must do work on the rubber walls of the balloon and the air around it to accomplish this expansion. Because some of the heat energy added to the balloon was used for pv work, only the remaining portion of the heat will go toward increasing the average kinetic energy of the molecules (i.e., temperature). So, when heat enters a system, if the system is capable of volume change, heat can go to pv work, increased temperature, or both. For this reason, the addition of a certain amount of heat will NOT necessarily be exactly proportional to the resultant increase in temperature. Some of the temperature which is energy, is doing work or PV, thus energy is lost, the remaining energy goes directly to increasing temperature, but it has lost some of the energy due to work. If the system is not capable of changing volume then no pv work can be done, so all of the added heat will go toward an increase in temperature Q4. For the same system, which heat capacity will be greater, the constant volume heat capacity or the constant pressure heat capacity? If the volume is held constant, then 100% of the energy added will go toward an increase in temperature. If the pressure is held constant the volume can still change and therefore some of the added heat will go toward pv work. If we think of heat capacity as "the amount of energy we can add before the system increases by one temperature unit," it is fairly easy to see that the system capable of pv work will be able to absorb more heat before increasing by one degree Celsius or Kelvin. It is much like asking how many gallons of water can be added to Tank A vs. Tank B? Tank A and Tank B are both 5-gallon tanks, but Tank B is connected via a hose to a reserve tank that holds 2 gallons. So, you can add 5 gallons to Tank A before it is "full" (analogous to a one unit increase in temperature). However, you can add 7 gallons to Tank B before it is full (the reserve tank being analogous to pv work). We would therefore say that Tank B has the higher "water capacity" in terms of our analogy. This indicates that the constant pressure heat capacity (allows for pv work; i.e., includes the 2-gallon reserve tank) will be more than the constant volume heat capacity (does not allow for pv work; i.e., no reserve tank) for the same system.

Real Gases

THe Greatest Deviation between ideal gas behavior and real gas behavior occurs when: a) temperature is extremely low--- produce smaller pressure than predicted by ideal gas law b) the pressure is extremely high--- gas molecules occupy greater volume At very high pressure, the molecules are pushed really close together, and their actual size becomes comparable to 0, meaning there is no distance between them. At every low temperature- the interaction of gas molecules becomes more important. Both cases result in deviations from ideal gas low 2) Increase inter-moleculer attractions decreases pressure in real gases, aka large a' = small P --- If PV/nRT > 1 it is due mostly to the molecular volume assumption 3) Increased molecular volume, increases volume in real gases --- If PV/nRT < 1 it is due mostly to the inter-molecular forces assumption In real gases volume is MORE than would be predicted by the ideal gas law because real molecules do occupy some volume. Notice that this is an INCREASE. By contrast, in real gases pressure is LESS than predicted by the ideal gas law. This is because real molecules do experience intermolecular attractions—forces that tend to slow down the molecules as they collide with the walls of the container and therefore pressure. Notice that this is a DECREASE. Looking at the ratio PV/nRT, we see that both pressure and volume are in the numerator. As a result, the "real" deviations just described that increase volume will cause PV/nRT to increase to greater than one, and "real" deviations that decrease pressure will cause PV/nRT to decrease to less than one. Thus use Van der Waals Equation, but not important for MCAT

Condosity:

The "condosity" of a solution is the concentration (molarity) of an NaCl solution that will conduct electricity exactly as well as the solution in question. For example, for a 2.0 M KCl solution, we would expect the condosity to be something more than 2.0. Why would we expect it to be above 2.0? Because potassium is more metallic than sodium. Thus, we know that it will be a better conductor. This means the NaCl solution will have to be slightly more concentrated in order to conduct electricity as well as the KCl solution. (look at metallic character, more metallic character, it's a better conductor... ALWAYS COMPARING TO SODIUM CHLORIDE Q16. What is the expected condosity of a 3.0 M LiCl solution? Sodium is more metallic than lithium, so we would expect an NaCl solution to conduct electricity better than an equimolar LiCl solution. This means the NaCl solution would need to be less concentrated in order to conduct equally as well. This predicts a condosity of something less than 3.0 for a 3.0M LiCl.

Geometric Isomers

The E/Z Convention: prioritize the two constituents on each carbon by molecular weight (as you do for R/S). If the two higher priority substituents are on the same side = Z. If the two higher priority substituents are on opposite sides = E Remember the following regarding geometric isomers: a) Cis isomers often have a dipole moment, but trans isomers usually do NOT (i.e., cis- 1,2-dichloroethene vs. trans-1,2-dichloroethene) b) Cis isomers often experience "steric hindrance," resulting in a higher energy molecule, but trans do NOT. Less stable molecules have higher heats of combustion than do stable molecules, so the cis- version will have a higher heat of combustion than the -trans version. Boiling Point- Since cis has dipole moment, this increase intermolecular forces thus increasing boiling point Trans molecules stack better then cis, thus trans have higher melting points because cis can't stack as well.

Gas Solubility

The solubility of gases in liquids follows a trend that is exactly the opposite of the solubility of solids in liquids. For gases dissolved in liquids, increased temperature decreases solubility and decreased temperature increases solubility. o Increasing the vapor pressure of gas X over a liquid increases the solubility of gas X in that liquid (This is why they pressurize soda pop cans with excess CO2). o Polar and non-polar gases easily form homogenous mixtures.

Intermolecular Forces: Surface Tension

The intensity of intermolecular forces, per unit length, at the surface of a liquid. Q55. Explain conceptually why an entire pin can float on water, but a small section cut from the end of the very same pin will not float. Doesn't the small section of the pin weigh less? Surface tension is a function of the strength of the intermolecular forces between the molecules of the liquid. To break through the surface of the liquid, a certain number of these bonds must be broken. The greater the ratio of length to mass, the greater the chance that the mass of the object can be supported by a large number of bonds. This is the case when the pin is whole. For the small section of the pin, however, it does not cover a very large area of the surface and therefore fewer intermolecular forces are involved. In this second case, the mass is greater than what can be supported by the small number of intermolecular bonds, and it is therefore able to break through the surface. A water skeeter can stay afloat atop the water because of this principle. However, if the water skeeter tried to balance on one leg, he would quickly sink!

Metallic Character

The metallic character of an element can be defined as how readily an atom can lose an electron. From right to left across a period, metallic character increases because the attraction between valence electron and the nucleus is weaker, enabling an easier loss of electrons. Metallic character increases as you move down a group because the atomic size is increasing. When the atomic size increases, the outer shells are farther away. The principle quantum number increases and average electron density moves farther from nucleus. The electrons of the valence shell have less attraction to the nucleus and, as a result, can lose electrons more readily. This causes an increase in metallic character.

Mass Spectrometry

The molecules of the sample are bombarded with electrons causing them to both break apart into smaller pieces and ionize This produces fragments iwth different masses and charges These fragments are accelerated through a narrow curved magnet called a flight tube Only particles with a certain mass-to-charge ration (m/z) will follow the the curved path and NOT hit the wall and exit onto the detector at the end of the flight tube. The strength of the magnetic field is varied from low to high, changing the curvature until all fragments have hit the detector THE HEIGHT OF EACH PEAK GIVES THE RELATIVE ABUNDANCE OF THAT FRAGMENT Parent peak= Original molecule - 1 electron --- Usually the last peak to the right, also known as M⁺ Base peak= Most common fragment and most stable, 100% in relative abundance. It is the highest peak on the spectra and the height of all other peaks will be a function of how abundant that fragment is compared to the base peak --- Always the Tallest peak

Valence

The number of bonds an atom "normally" makes: carbon and its family are tetravalent; nitrogen and its family are trivalent; oxygen and its family are divalent and fluorine and its family are monovalent. The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.

. For a reaction with two reactants, A and B, a graph of 1/[A] vs. time is non-linear. Which of the following is known? 1) The reaction cannot be second order in A and independent of B, 2) Reactant B must be involved in the rate law, 3) Reactant B cannot be in excess.

The observation that a graph of 1/[A] is non-linear is somewhat inconclusive. The graph could have been non-linear because both reactants are impacting the rate (violating the rule that these graphs will only be linear if only one reactant species is impacting rate). However, it could also be non-linear if reactant A is the only reactant impacting rate, but reactant A is not second order. For example, suppose that reactant A is actually first order; the graph of 1/[A] would not be linear, but the graph of ln[A] would be. Statement 1 is the best choice because if reactant A was second order and reactant B did not impact rate, we would expect a linear plot. Statement 2 is NOT known. Reactant B could be in the rate law and that is why the graph is not linear; however, it is equally plausible that reactant B is NOT in the rate law and the graph of 1/[A] is not linear because A is first order, not second order. Statement 3 is NOT known either. As we have already explained, the graph could be linear either way. If reactant B is in excess then the graph could be non-linear because reactant A is actually first order, not second order. If reactant B is not in excess (and is in the rate law) then the graph could be non-linear because both A and B are impacting rate.

Elastic Potential Energy

The potential energy stored in a compressed spring (or in any other object that follows Hooke's Law). It is the energy that is stored as a result of APPLYING A FORCE to deform an elastic object. Examples of this is with pulling a rubber band, an archer's stretched bow, a bent diving board PE = (1/2)k∆x^2 Although the above formula can obviously be used to solve for k, ∆x or PE, it is more likely to be used in connection with the conservation of energy. If a ball with velocity v strikes a spring, compressing it, all of the ball's kinetic energy will turn into elastic potential energy. Setting the initial kinetic energy equal to the final potential energy allows you to predict how far the spring will compress (∆x). -KE=PE -1/2(mv^2)=(1/2)k∆x^2 -REMEMBER, ITS ALWAYS FROM THE EQUILIBRIUM POINT, WHETHER IT'S FROM HORIZTONAL OR NEGATIVE POSITION. In the vertical position, you don't need to worry about the spring stretching, conceptually, the gravity and weight creates a new equilibrium point. When the PE has reached equilibrium position after springing, it will turn into KE Q41. True or False? 1) A ball moving with twice the kinetic energy can compress a spring twice as far. 2) A ball moving with three times the velocity can compress a spring three times as far. 1) False. Whatever KE the ball has will be transferred completely into elastic PE so we can write KE = (1/2)kx^2. We see that KE is related to the square of x, so it will require four times the kinetic energy to compress the spring twice as far. 2) True. We can also write (1/2)mv^2 = (1/2)kx^2. This shows that velocity and the distance of compression, x, both have a square; and are therefore directly and linearly related.

Enzyme vs Catalyst

The word catalyst is a more general term for any substance that increases the rate of a reaction without being altered or consumed during the process. An enzyme is one type of biological catalyst. Enzymes are long protein chains folded into complex tertiary structures that feature an active site that is unusually specific to the reactants and/or transition state of the reaction it catalyzes It could be said that all enzymes are catalysts, but there are many catalysts that are not enzymes. In fact, the catalysts you will encounter in general chemistry are almost always inorganic compounds or solid metals. Some texts define "catalyst" as being inorganic molecules that catalyze reactions, and enzymes as being organic molecules that catalyze reactions. However, because an enzyme is still "catalyzing" a reaction, we think the use of the term "catalyst" as a more categorical term makes the most sense.

Theoretical Yield

Theoretical Yield: the amount of product in grams that would be produced if the reaction ran 100% to completion. In other words, you take your limiting reagent, do a mole-to-mole conversion to get moles of product, and then convert that to grams. Actual Yield: Actual yield is just what it sounds like, the amount of product in grams you obtain at the end of the actual experiment in the lab Percent Yield: The percent yield is just the ratio of the actual yield over the theoretical yield multiplied by 100. Remember that yield is a function of reactants and equilibrium, NOT rate, FOCUS ON THESE TWO WAYS TO INCREASE YIELD: 1) Start with more reactants 2) Shift the equilibrium to the right using one of the actions described by Le Chatelier's Principle The most common method of shifting the equilibrium in this way is to remove products as they are formed. By doing so, you force the reaction into a constant state of "catch up." The reaction continually produces more product in an attempt to reach equilibrium. CAVEATS: Action 1) above will increase overall quantity of yield, but NOT percent yield. Furthermore, it will only work if you add more of the limiting reagent. Adding more of any non-limiting reagent (i.e., a reagent that is in excess) will have no effect. Moles of Oxygen Needed for Combustion: You will occasionally be asked to predict the species that will require the most oxygen to combust. Here is a simple ranking system to make such predictions quickly: o Add 1.0 for each carbon and subtract 0.5 for each oxygen. The higher the resulting number the more oxygen necessary for full combustion. This is NOT, however, the actual number of moles required—this is only a ranking system. The only way to determine the exact moles of oxygen required for a combustion reaction is to write out and balance the combustion equation.

ΔH RXN the enthalpy change for a reaction:

This is usually calculated by adding reactions (and their associated enthalpy changes) from a table. You must select the reactions from the table that—when added together—will produce the net reaction for which you are calculating ∆HRXN. To calculate ∆HRXN you will add all of the values given for each of the reactions you use, paying careful attention to signs and stoichiometry. If the reaction proceeds in the same direction as it would in the net reaction, use the value given directly. If it proceeds in the opposite direction, change the sign of the value given. You MUST multiply the number given in the table by the coefficient in the balanced net reaction. For example, suppose one of the reactions given was the formation of liquid water from the elements hydrogen and oxygen: 1/2O2 + H2 -> H2O ∆H° f = -285 kJ/mol, but in your net reaction water is a reactant rather than a product. You would need to change the sign of ∆H° to be positive and combine it with the enthalpy changes from the other reactions used. If your balanced net reaction contained two moles of water, you would need to double the value given, and so forth.

Q35. Describe how you could use the rate order graphs to determine the order of each reactant in a multi-reactant reaction experimentally in the lab: What would you need to measure? What would you do with the data?

To determine the order of each reactant experimentally you would only need to ensure that all other reactants were in excess and measure the concentration of the limiting reactant as a function of time. You would then use the measured concentration of the reactant in question in each of the types of graphs. If all other reactants are in excess, one of these graphs should be linear. You may be tempted to think that you wouldn't get a positive result if the reactant you were testing was NOT impacting rate. However, that would produce a line for [A] vs. time (i.e., the reaction would zero order in that species). Remember that zero order reactants are not included in the rate law!

Enantiomers

Two molecules with the same molecular formula and the same bond-to-bond connectivity that are non-identical, non-superimposable mirror images. They contain at least one chiral center. Non-superimposable mirror image • Remember the following regarding enantiomers: a) They have opposite R/S configurations at every chiral carbon (mirror images). b) They rotate plane-polarized light to the same degree, but in different directions. c) They have all the same physical properties (boiling point, reactivity, etc.) EXCEPT for: a) how they rotate plane polarized light b) the products they form when reacted with another chiral compound.

Equilibrium on an Inclined Plane

Use altered Coordinate system Write down all of the forces acting on the object in two separate columns All forces acting down= Down forces --- F=mgsin (theta) force due to gravity All forces acting up= Up Forces Force friction always parallel to plane but opposite of sliding motion After accounting for all possible forces, set the sum of down forces= sum of up forces and solve for unknown F (down)= F (up)

V = √(2gh)

Use it when asked for final velocity, given drop height. You can also use it as a stepping stone to find the final velocity. Once you know final velocity, you can intuit all other parameters of the motion using the same conceptual steps given previously.

Right Hand Rule

Used for magnetic fields Use for (+) charges Thumb is velocity Pointing finger is direction of magnetic field Middle finger is direction of magnetic force or using other right hand rule, palm of hand is the direction of magnetic force, thumb is velocity/direction, fingers is direction of magnetic field

NMR Spectroscopy

Used to differentiate molecules based on differing chemical environments of Hydrogen Nuclei (H-NMR) or differing carbon nuclei (C13-NMR) H-NMR is tested about 90% of the time An atom must have either an odd atomic number or an odd mass number to register on an NMR All nuclei with an odd atomic or mass number will have a nuclear spin, analogous to electron spin, causing a changing electric field aka a magnetic field With a magnetic field is applied to nuclei, nuclei align their magnetic fields with the direction of the external magnetic field. If nuclei are exposted to photons, some nuclei will absorb the photon energy and flip their orientation so that they are lined up against the external field The absorbed energy is picked up by NMR. Different nuclei will require a different frequency photon to cause this flip in orientation, THESE DIFFERENCES CAUSED BY THE DEGREE TO WHICH EACH NUCLEUS IS SHIELDED BY NEIGHBORING HYDROGENS

Affinity Chromatography

Used to isolate a specific molecule or product based on a very specific affinity or binding interaction Example- Molecules in mixture react via acid-base neutralization with molecules on the column. To elute the bound target molecule, one must disrupt the binding interaction. This can be done with a salt solution or a chemical reversal of the reaction bound to the target to the column.

Vapor Pressure

Vapor Pressure (Vp) is the partial pressure of the gaseous form of a liquid that exists over that liquid when the liquid and gas phases are in equilibrium. Vapor Pressure Elevation/Depression: 1)temperature- --- ↑ Temp,= ↑ Vp due to ↑ in KE, thus higher avg KE with ↑ Temp 2) non-volatile solute- ---↑ non-volatile= ↓Vp 3) Volatile Solute- --- ↑ V.S.= ↓ Vp: if Vp of V.S. < Vp of pure solvent ---↑ V.S.= ↑ Vp: if Vp of V.s. > Vp of pure solvent,

Acid/Base Clarification

When we add an acid or base to water, the equilibrium of that acid or base will directly impact the equilibrium for the ionization of water according to Le Chatelier's Principle Notice that the addition of either an acid or a base shifts the equilibrium for the ionization of water to the left! The equilibrium for the ionization of water is always present in aqueous solutions. Adding an acid shifts the reaction to the left, and increases the relative [H+] Adding a base shifts the reaction to the left, and increases the relative [OH-] Kw, Ka and Kb are used to describe these three equilibriums. At 25°C, Kw = Ka*Kb; this should make sense because 1) we demonstrated above that this is mathematically true, and 2) if we always remain at 25°C the Kw for the ionization of water should never change—per our rule that temperature is the only thing that changes Keq.

Force Vectors in Two-Dimmensions

With force in 2D, example if force is at angle of 30' to horizontal, add to table that the formula that predicts the compnent of the force actin gup, down, left or right Example- A rope is attached to a box on the right side at an angle of 60' to the horizontal and applies a force of 100N, on your scratch paper, under forces to the right, put 100cos(theta), this formula will give the rightward force in the x-direction exerted on the box by the rope

Pressure-Volume (PV) Work

Work is energy transfer via a force (physics), or via a change in volume at constant pressure (chemistry). PV Work = P∆V (requires constant pressure, any change in volume tells you there is pv work) On a pressure vs. volume graph, the area under the curve is pv work. Q7. Which of the calorimeters described above allows for pv work? - Coffee calorimeter, because it utilizes constant pressure and utilizes a change in volume.

Calculating Solubility

Write out the Ksp expression. Substitute into the expression the value given for Ksp. Substitute a factor of x into the equation for the concentration of each ion, using 2x, 3x, etc., if more than one mole of each ion is produced (Hint: Ask yourself, "If x moles of the reactant are dissolved, how many moles of each ion will be produced?"). Solve for x. Your answer, "x" is the "solubility" of that particular specie.

Calculating ΔHRXN Using Bond Energies:

You can also calculate the enthalpy change of a reaction using bond energies To do so, simply add up the bond energies of all of the products and reactants. If a bond is broken during the reaction, energy is required, so the bond energy should be given a positive sign. If a bond is formed, energy is released, so the bond energy should be given a negative sign Bonds made= - Bonds broken= + Once again, multiply all bond energy values by their coefficients in the balanced equation.

Activation Energy (Ea)

You can think of the activation energy as a barrier to the reaction. Only those collisions which have energies equal to or greater than the activation energy result in a reaction. Remember that for a reaction to happen, particles must collide with energies equal to or greater than the activation energy for the reaction

Solving circuits using Ohm's Law: Third

You can use Ohm's Law across a single resistor. Doing so may be necessary to get a piece of information needed to simplify the circuit. Be sure you are using only information for that resistor and NOT for the main battery, current through the circuit as a whole, etc. Ohm's Law across a resistor states that: Voltage drop across that resistor = current through that resistor multiplied by the resistance of that resistor.

Young's double Slit Experiment

Young shone a monochromatic light through a screen with a single slit in it Purpose of this slit was to create coherent wave-fronts. Behind the 1st screen he placed a second screen with two narrow, parallel slits, these created the diffraction pattern Finally, behind the second screen he placed a third screen Light raveled through the first two screens and formed alternating patterns of light and dark bands on the third screen

Van Der Waal's equation

[P + a'(n/V)² X [(V/n)-b']= RT a' is a constant that represents the actual strength of intermolecular attractions b' is a constant that represents the actual volume of molecules The Van der Waals equation has never been on the MCAT and it should NOT be memorized. We present it here because it demonstrates a few important principles you should know for the MCAT: 1) Rules for manipulating Equations, you cannot use manipulating equation skills we presented on an equation that involves addition or subtraction 2) Increase inter-moleculer attractions (a') decreases pressure in real gases, aka large a' = small P 3) Increased moleculer volume (b') increases volume in real gases

Cell Potential

aka Cell EMF or E° cell The cell potential or E° cell is the SUM of E° potentials for two half rxns that make up an electrochemical cell Remember the following: 1) Half rxns ALWAYS come in pairs- one reduction half rxn + one oxidation half-rxn ---When one species is reduced, the other must be oxidized 2) Normally, reduction half rxns are given in tables. The oxidation half rxn is the REVERSE of the REDUCTION half-rxn --- E° for any oxidation halfrxn is simply the negative of E° for the associated reduction half rxn --- example- if a two species compared were -.32V vs -.5V, due to -.32V being greater, it is the reducing half rxn and -.5V is oxidation, thus its -.32V + .5V= .28V for the E° cell 3) You CANNOT add two E° values directly of a half-rxn table, all the reduction half rxn, thus you need one reduction and one oxidation: REVERSE the half rxn of the species with the LOWEST reduction potential and take the sum to get cell potential (E°cell) 4) DO NOT USE STOICHIOMETRY, one mole of Cu²⁺ has the same reduction potential (E° potential) as two moel-s of Cu²⁺ A strong oxidizing agent has a HIGH reduction potential, it is going another agent to be oxidized, and the oxidizing agent itself is gaining e-

Hydrate

an inorganic compound in which water molecules are permanently bound into the crystalline structure. The nomenclature of a hydrate is altered to reflect the presence of water molecules. For example, anhydrous cobalt(II)chloride contains no water, but cobalt(II)chloride hexahydrate [CoCl2∙6H2O] contains six water molecules complexed with each cobalt

Electron Orbitals

an orbital equates to a room and each room has two beds to be occupied by a maximum of two persons/electrons. There is only one room in an s subshell (studio apartment) and it can hold two electrons. There are three bedrooms in a p subshell and each bedroom can hold two electrons for a total of six. There are five bedrooms in a d subshell and each bedroom can hold two electrons for a total of ten. There are seven bedrooms in an f subshell and each bedroom can hold two electrons for a total of fourteen. Much like teenagers, electrons do NOT like to share rooms. Therefore, they will always fill empty orbitals first and only pair up inside the same orbital once it becomes necessary.

Unsaturated Solution

any solution that contains less than its maximum amount of dissolved solute. For unsaturated solutions the Ksp is greater than the ion product. A super-saturated solution is a solution that contains more dissolved solute than predicted by the solubility product constant—in other words, the ion product exceeds the Ksp without a precipitate forming

Converging Lense

convex, positive usually produces a positive, real, inverted image. When the object is inside the focal point it produces a negative, virtual, upright image. ex- human eye, magnifying glass When the object is inside the focal point it produces a negative, virtual, upright image. This is the case with a magnifying glass. In order to see the magnified image the object must be inside the focal point of the lens. This is also supported by the formula for magnification, which shows us that in order for the image to be magnified the distance between the object and the lens must be less than the distance between the observer (image) and the lens (M = -di/do).

How does the addition of a non-volatile solute affect vapor pressure?

decreases. it occupies a portion of the surface area available for vaporization 2) non-volatile solute- ---↑ non-volatile= ↓Vp due to n.v. occupies portion of limited surface area for vaporization. This causes liquid molecules unable to exit due to non-volatile solutes stopping the exit ports. ---Vp = XVp° ---Vp + n.v.s= some fraction of vapor pressure for pure solvent, X= mole fraction, Vp equal actual Vp, and Vp°= Pure solvent Vp

Electron Donating Groups

donate electrons and thus stabilize positive charge; make a molecule more basic; decrease acidity of alcohols An electron donating group on the carbonyl carbon will decrease its partial positive charge and thereby make it less able to stabilize the conjugate base.

Isotopes

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element. Isotopes of an element will contain the same number of protons and electrons but will differ in the number of neutrons they contain. In other words, isotopes have the same atomic number because they are the same element but have a different atomic mass because they contain a different number of neutrons An isotope is one of multiple versions of the same atom that have differing numbers of neutrons. All isotopes must have the same Z number because it is the number of protons that defines the atom as a specific element (carbon, hydrogen, etc.). If you know the Z number you know the element. All isotopes do not have an odd mass number (carbon-14), although many do (iron-57). For example, carbon is normally present in the atmosphere in the form of gases like carbon dioxide, and it exists in three isotopic forms: carbon-12 and carbon-13, which are stable, and carbon-14, which is radioactive.

Electrolytic Cell

electrolysis is a technique that uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. It is a galvanic cell to which an external voltage is applied, forcing the electrons to flow in the OPPOSITE direction Oxidation still occurs at the anode and reduction at the cathode The species with the LOWER reduction potential will be REDUCED, unlike the galvanic cell- ex= .32V vs .88V, .32V has lower reduction potential is thus reduced and .88V is oxidized The cell potential E° cell will ALWAYS be negative The sum of the externaly applied voltage (V battery) and the negative cell potential (-E° cell), in volts, must be positive Cathode= (-) Anode= (+) reduction still ALWAYS happens a the cathode This is different compared to galvanic cells

Electron donating Groups

electron donating group (EDG) or electron releasing group (ERG) is an atom or functional group that donates some of its electron density into a conjugated π system via resonance or inductive effects, thus making the π system more nucleophilic. Alkyl groups are weak EDG Amines are EDG Alcohols are EDG

Solvation

the process of surrounding solute particles with solvent particles to form a solution process wherein solvent molecules surround a dissolved ion or other solute particle creating a shell. Hydration is a specific kind of solvation wherein water is the participating solvent. Water molecules, being polar, can surround both negatively and positively charged solutes by directing either their partially-negative oxygen, or partially positive hydrogen, moieties toward the ion.

Limiting Reagent

o You must have a balanced equation. o You must convert to moles first. o Compare the number of moles you have to the number of moles required to run one cycle of the reaction, as indicated by the coefficients. The reactant you will run out of first is the limiting reagent. o The reactant you have the least of, in either grams or moles, is NOT necessarily your limiting reagent. For example, suppose for the combustion of methane you have 1.5 moles of O2 and only 1.0 mole of methane. Because you need two moles of O2 to react with one mole of methane, you will run out of O2 first and it is therefore your limiting reagent—even though you have more moles of O2 than you do methane. https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/limiting-reagent-stoichiometry/v/limiting-reactant-example-problem-1

Third Quantum Number

o a.k.a. "mℓ" or "the magnetic quantum number" o Gives the orbital orientation; has a value of -ℓ to ℓ (from the azimuthal quantum number) Designates the orientation of the subshell where an electron is most likely to be found (i.e., which "dumbbell" of a p subshell) The orientation of the orbital around the nucleus mℓ= -ℓ to +ℓ So if ℓ=0, then mℓ=0, means there is only one orientation around the nucleus, and a sphere only has one orientation around the nucleus ℓ=1, mℓ= -1, 0, +1, 3 possible values, this tells us that there are 3 possible orientations. We have 3 possible orientations for the p orbital, or the dumbbell shape.

pOH = -log[OH-]

pH of pure H2O at 25°C = 7.0, and the [H+] = [OH-]; pH > 7 = basic, and the [H+] < [OH-]; pH < 7 = acidic, and the [H+] > [OH-]; pH = 7 is defined as "neutral" and the [H+] = [OH-]

Axial vs. Equatorial

red=axial blue= equatorial On the chair conformation of cyclohexane the axial substituents rise vertically from the ring and the equatorial substituents extend horizontally. Large substituents are more stable (i.e., lower energy) when in the equatorial position. cis-1,2- dichlorocyclohexane cannot exist with both chlorines in the equatorial position. For neighboring carbons, two equatorial substituents would be trans to one another. Thus the need for the two neighboring substituents can be cis to one another, but one must be in the axial position and one in the equatorial position.

∆G° = - RTlnKeq

relates the equilibrium constant to the Gibbs free energy (Note: Remember that the ln of any positive number less than 1 is negative). A useful rearrangement of the above equation: Keq = e^-ΔG/RT Q15. If the value of Keq is known, what can we infer about ΔG°? If a reaction is spontaneous, what can we infer about the rate of that reaction? If the value of K is greater than one then the reaction will be spontaneous. To be more precise, if we are starting at the standard state conditions, then we know the reaction will proceed spontaneously. We know this because the natural log of a number greater than one is positive, which will result in a negative Gibbs Free Energy per the equation given. If the value of K is less than one then the reaction will not proceed spontaneously from standard state conditions. We know this because the natural log of a number less than one is negative. This negative will counteract the existing negative in front of the equation and therefore the sign of Gibbs Free Energy will be positive. If K = 1, then ∆G = 0 because the natural log of one is zero. Again, a key principle in this section is that kinetics is "walled off" from thermodynamics: the value of K will not tell us anything at all about the rate of the reaction.

Phase

relative measure of how closely two waves (typically with the same frequency) are oriented to one another in space, expressed in radians or degrees. Two waves that are "in phase" should cross the x-axis at the same point, but may have different amplitudes. The easiest way to think of phase is as horizontal displacement of the sine wave from the y-axis on a graph. Two waves cannot have different wavelengths and share the same displacement cycle after cycle. Neither can they match if they have different frequency or period. It also helps to visualize that only waves EXACTLY in phase can add via totally constructive interference. Two waves with different amplitudes could still add entirely, but differences in frequency, period or wavelength would make them offset and unable to add via totally constructive interference.

Heat of Combustion

the amount of energy released when a molecule is combusted with oxygen. All covalent bonds are broken and reformed in a radical reaction. The higher the energy of the molecule (i.e., less stable) the higher the heat of combustion. LESS STABLE BONDS=LOW ENERGY BONDS=HIGH ENERGY MOLECULE=HIGHER HEAT OF COMBUSTION Why do bonds form? Is energy required or released when a bond is formed? -Atoms are without feelings and don't "want" to form bonds. They only do so in situations where the resulting bond is a lower energy state than was the unbonded form (or than the previous bonds they were engaged in with other atoms) As a result, FORMING BONDS ALWAYS RELEASE ENERGY. This is a major point of confusion for students. ATP is often the molecule that exacerbates this confusion. The transition from ATP to ADP does release energy, but only because the forming of the new bonds in ADP releases more energy than was required to break the bonds in ATP—NOT because breaking the bonds in ATP released energy. FORMING BONDS RELEASE ENERGY

Mechanical Waves

the energy is transferred by vibrations of medium (medium = matter) ex/ ocean waves move through water Require a medium to propagate; cannot propagate in a vacuum; transfer energy in the direction of propagation, but do not transfer matter. Whether or not mechanical waves transfer momentum is something physicists like to debate, so the MCAT won't test that question directly. (e.g., sound waves, a wave on a string, ocean waves, etc.) Transverse (e.g., strings on a musical instrument); Transverse mechanical waves require a fairly stiff medium to propagate and therefore cannot propagate in liquids or gases. Longitudinal (e.g., sound waves)

Bond Energy

the energy stored in the bond. This is also the amount of energy that will be required to break the bond Don't confuse this; stable compounds such as N2 have the highest bond energies. Unstable compounds, such as ATP, have LOW bond energies. ATP- highly unstable= low energy bonds H2- Highly stable- high energy BONDS When something is said to be a "high energy" molecule that does NOT mean it has high bond energy. In fact, it means the very opposite. It is unstable and thus requires very little energy to dissociate the bond. ATP is high energy, thus highly unstable Bond energy is a measure of the strength of a chemical bond. The larger the bond energy, the stronger the bond HIGH ENERGY MOLECULE= LOW ENERGY BOND LOW ENERGY MOLECULE= HIGH ENERGY BOND

Thermodynamics

the thermodynamics of a reaction reflect the potential reactivity (for example, given infinite reaction time) and includes all measurements of energy flow and relative stability. ∆H ∆G ∆S Keq A simple, but effective conceptual approach to thermodynamics is to think of it as differences in energy across a reaction. If the bond energies of the reactants are lower than the bond energies of the products, then the products are by definition more stable. We would expect therefore, that as the molecules transform from a less stable state to a more stable state there would be a release of energy (i.e., an exothermic process). If the reverse is true we would expect that energy would be required (i.e., endothermic) to drive the molecules from a more stable state (higher BE) to a less stable state (lower BE). Entropy works in a similar way, but it is a measure of randomness or disorder and has the units of energy/temperature (J/K). It requires energy to create order. Conversely, there is an energy release associated with going from a more ordered state to a less ordered state. Gibbs free energy combines these concepts and represents the total free, available energy either produced or required by a reaction as a function of BOTH changes in the bond energies (∆H) and changes in the entropy state (∆S). It is IMPERATIVE that students understand that the rate of a reaction is independent of its thermodynamic properties.

Coffee Cup Calorimeter

use q=mc∆T c= specific heat capacity NOT HEAT CAPACITY - When a chemical reaction occurs in the coffee cup calorimeter, the heat of the reaction if absorbed by the water. The change in the water temperature is used to calculate the amount of heat that has been absorbed (used to make products, so water temperature decreases) or evolved (lost to the water, so its temperature increases) in the reaction. -Utilized constant pressure, The coffee cup calorimeter allows for an increase in volume of the solution inside the coffee cup, but remains at atmospheric pressure throughout -A coffee cup calorimeter is a constant pressure calorimeter. As such, the heat that is measured in such a device is equivalent to the change in enthalpy. A coffee cup calorimeter is typically used for solution based chemistry and as such generally involves a reaction with little or no volume change. A coffee cup calorimeter is great for measuring heat flow in a solution, but it can't be used for reactions which involve gases, since they would escape from the cup.

KE = E - φ

where E is the amount of energy added or photon energy KE is the kinetic energy of the ejected electron The amount of energy required to do this is called the "work function," and is usually given the variable φ, or the work function of the metal E can be replaced with hf, the formula for energy of a proton One of the most important take-home messages is that more INTENSE light [i.e., same wavelength, but more photons striking the metal per second] does NOT increase the KE of ejected photons, but DOES increase the number of photons ejected. Meanwhile, changing to a higher frequency light [i.e., blue light replacing red light] DOES increase the KE of the ejected electrons [as long as the work function has been exceeded].) Light intensity or wavelength does not increase KE, only increases # photos ejected Higher frequency DOES affect speed or KE of photons being ejected ex- 700J at a rate vs 1 X 10^5 protons vs 350J and a rate of photos at twice the first rate, means that the second source will eject twice as many electrons as the first. The left energy will be KE, which can be used to solve for velocity using 1/2mv^2=KE

The Doppler Effect

Δf/fs = v/c Δλ/ λs=v/c REMEMBER 3 KEY POINTS: a) v is RELATIVE velocity, not velocity of either object b) variable c is speed of wave, either 3 X 10⁸m/s for light or 340 m/s for sound c) the answer is the CHANGE in frequency or wavelength, this value most be added or subtracted to the initial value to get the actual value due to doppler effect. ---- Add the frequency (subtract from wavelength) if the relative motion is toward each other and add if relative motion is away from each other Perceived by the observer is depended upon the RELATIVE VELOCITY between the SOURCE and OBSERVER ---- The greater the relative velocity, the greater the shift in frequency of wave length, so when we see something faster, we see a greater change in λ or f ---- these patterns only hold true when relative velocity, v, is smaller than speed of wave, c ----- Greater relative velocity results in greater Doppler shift ----- Light, begin much faster wave than sound, produces a much smaller fractional change in f for same relative velocity There will be no doppler effect if two objects are traveling in the same direction at same velocity, but there will be if they are traveling two different directions even at the same velocity

Gibbs Free Energy (∆G)

∆G = the amount of "free" or "useful" energy available to do work (excluding pv work ΔG can predict the direction of the chemical reaction under two conditions: constant temperature and constant pressure. If energy is available and the system can do work, Gibbs Free Energy is negative If energy must be added to the reaction (e.g., heat must be added to the system) to make it proceed, Gibbs Free Energy is positive. o Units: Joules Spontaneous - is a reaction that is consider to be natural because it is a reaction that occurs by itself without any external action towards it. Non spontaneous - needs constant external energy applied to it in order for the process to continue and once you stop the external action the process will cease negative ∆G = Spontaneous process; free energy available to do work. -ΔG<0 : reaction is spontaneous in the direction written (i.e., the reaciton is exergonic) positive ∆G = Non-spontaneous process; no free energy available; energy is required. -ΔG>0: reaction is not spontaneous and the process proceeds spontaneously in the reserve direction. To drive such a reaction, we need to have input of free energy (i.e., the reaction is endergonic)

Important signs of Enthalpy, Entropy, Temperature, Gibbs

∆G = ∆H - T∆S +∆S = increased randomness, and thus more energy available to do work. becoming less ordered -∆S = decreased randomness, and thus less energy available to do work., becoming more ordered -ΔG<0 : reaction is spontaneous in the direction written (i.e., the reaciton is exergonic) (ΔG is negative) +ΔG>0: reaction is not spontaneous and the process proceeds spontaneously in the reserve direction. To drive such a reaction, we need to have input of free energy (i.e., the reaction is endergonic) (ΔG is positive) +ΔH>0: Endothermic reaction -ΔH<0: Exothermic Reaction When temperature is high, entropy is favored When temperature is low, entropy isn't favored