UWORLD - General Chemistry

Arrhenius Equation

"Collision Theory of Kinetics" assumes that molecules must collide to react. These collisions must have enough kinetic energy to overcome the activation energy. This is expressed mathematically below. K=Ae^(-Ea/RT) K- rate constant (proportional to reaction rate, adversely affected by inhibitor) A- collision frequency (depend on concs) Ea- Activation Energy R- gas constant T- Temperature (K) (^temp^ rxn rate) Ex: If you increase the concentration of a reactant you will increase the collision frequency. If you increase the temperature that will result in a greater number of collisions. Adding an inhibitor would decrease frequency of collisions.

Molarity

# of moles of solute per liter of solution. Describes concentration M = Mol/l

Oxidation state of Oxygen in Cl-O^-

-2

Ionic bonds typically form with what kinds of atoms?

1 metal and 1 non metal

Out of the following Ka's, which is closest to the pH value of 6? 1.7 x 10^-7 6.5 x 10^-11 4.0 x 10 ^-3 2 x 10^-8

1.7 x 10 ^-7 has a pKa of 7, meaning it has a pH of 7 which is the closest to 6

20 ng of radioactive Y undergoes 3 half lives (half life is 64 hours). How much is left?

1/2^n, n = 3 1/2^3 = 1/8 = 2.5 ng

Molar mass of H2O

18 g/mol

Rank the orbitals in increasing energy

1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s

Decomposition of H2O2 results in what products?

2 H2O2 ---> 2 H2O + O2

Covalent bonds typically form with what kinds of atoms?

2 Non metals

To fully neutralize a solution that has H2PO4^-1, how many equivalences of NaOH are needed?

2, one for each acidic proton

Which group will contain atom w/ lowest second ionization energy? Group 1, 2, 14, or 16?

2. 1/2 automatically because they are metals and metals usually have lower ionization energy vs non metals. 2 especially because it has 2 valence electrons so the 2nd ionization energy would be removing 2 valence electrons. 1 has only one valence electron so it would have to remove a valence and core electron.

Balance the following equation: Ca(C2O4) + K3(C6H5O7) ---> Ca3(C6H5O7)2 + K2(C2O4)

3Ca(C2O4) + 2K3(C6H5O7) ---> Ca3(C6H5O7)2 + 3K2(C2O4)

Formal Charge of the oxygen from Cl-O^-

6 (valence e) - [ 6 (# of dots) + 1 (# of lines) ] = -1

If an atom has 8 electrons how many protons does it have?

8 protons! have EQUAL number of protons vs electrons

Homogenous Catalyst

A catalyst that is in the same phase as the reactants

Heterogenous Catalyst

A catalyst whose phase is different from the reactants. Typically solid interacting with gases and liquids, so more surface area on the solid catalyst = higher reaction rate. This is because adsorption occurs (one chemical substance collects on the surface of another substance)

Conductivity

A material's ability to allow heat or electric charges to flow. Metals > Metalloids > Nonmetals

Entropy

A measure of disorder or randomness. Increase in entropy (+∆S)? More thermodynamically favorable (non-spontaneous) as... ∆G = ∆H - T∆S Delta S

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons He attracts more electrons the Ca

Titration of a WA w/ a SB leads to what pH at the equivalence point?

A pH > 7 b/c you used a SB. If you titrated a WB w/a SA you would have a pH<7

First Order Reaction

A reaction in which the reaction rate is proportional to the concentration of only one reactant. So if you double both reactants concentration and the rate is only doubled, then it is a first order reaction as the rate is only doubled meaning it is only proportional to one reactant and not both. If It was proportional to both, then doubling the reactants concentration would quadruple the reaction rate and would be a second order reaction. One reactants conc is doubled? Reactant rate is doubled. Rate = k [A]^1 or k [B]^1 Dependent on only ONE of the reactants

Second Order Reaction

A reaction whose rate depends on the concentration of one reactant raised to the second power or on the concentrations of two different reactants, each raised to the first power. Quadruples the rate. Rate = k [A]^2 or k [B]^2 OR k[A]^1[B]^1

Periodic Table of Elements

A table that classifies elements by their physical and chemical properties; rows are called periods; columns are called groups;

Standard Temperature and Pressure (STP)

A temperature of 273 K, a pressure of 1.00 atm, and 1 mol of gas occupies 22.4 L

Beta Emission

A type of Beta Decay where ejection of an electron or a positron from the nucleus occurs. 1. B- decay (electron emission) - neutron converts to a proton and emits electron 226. 226 Ra ---> Ac 88. 89 2. B+ decay (positron emission) - proton converts to neutron and emits positron 226 226 Ra ---> Fr 88. 87 As atomic # changes the identity of the element changes accordingly

Delta S positive but Delta H negative is spontaneous RXN or not?

ALWAYS spontaneous b/c Temperature measured in Kelvin and Kelvin is NEVER Negative

Ka = [H+][A-]/[HA]

Acid disassociation constant

Acidosis and Alkalosis

Acid-Base Imbalances Acidosis = pH < 7.35 greater acid than base Alkalosis = pH > 7.45 greater base than acid

Titrations

Acid-base neutralization reactions can be used in titrations with an indicator to determine the concentration of an acidic or basic analyte. Analyte is the compound with unknown concentration which you wish to measure. The titrant is a measured amount of solution with a known concentration that is added to a solution containing the analyte. For example you add a base (titrant) to an acid (analyte) with an unknown concentration. This resulting acid base neutralization reaction produces a change in pH which is monitored by and Indicator. An indicator signals the equivalence point of the neutralization (point where acid and base equal a pH of 7). By assessing the equivalence point of neutralization, the volume of titrant required can be correlated to the amount of an analyte present in solution.

Polyprotic Acids

Acids that have more than one ACIDIC proton (H+ ion) that can dissociate in water and be donated.

Percent Yield

Actual yield/theoretical yield x 100 Efficiency of a reaction. Ratio of mass obtained from experiment/ the mass you should obtain in theory.

Acids and bases can

Aid the solubility of non polar analytes (compound in titration with unknown concentration that you wish to measure) by forming more soluble ionic salts. This gives it solubility in solvent which can then be titrated. If polar base needs to be dissolved in a non polar solvent, add an acid to protonate the base to make it non polar. Then you would want to titrate with a BASE since you made the solution acidic.

Half Life for Radioactive Particles

Amount of time needed for half the quantity of a substance to decay. The fraction of substance remaining after a number of halve-lives can be calculate by 1/2^n, where n is the number of elapsed half lives.

Electrons flow from the...

Anode (positive) to cathode (negative). Oxidation occurs at the anode and reduction occurs at the cathode. There are more anions at the anode and fewer cations. There are less anions at the cathode and more cations.

Density and Temperature Relationship

As temperature increases, density decreases. As temp decreases, density increase. INVERSELY proportional. Except with H2O, then decreased temp, decrease density

Are there mode cations at the cathode or anode?

At cathode. Cathode is where reduction occurs. AOCR

Paramagnetic

Atom or substance containing unpaired electrons and is consequently attracted by a magnet.

Neutrons

Atomic mass - Atomic number (proton #) = # of neutrons

Isotopes

Atoms of the same element just with different # of neutrons in nucleus. So mass number will be different (sum of # of protons and neutrons in nucleous). Since Isotopes have same number of protons (which determines their identity) they are the same elements and there for have the SAME chemical properties (electron config, and bonding/reacting tendencies). Since they have different number of protons however, Isotopes DIFFER in physical properties (mass/density)

Covalent Bond

Atoms share electrons through end to end overlap of atomic orbitals

Tendency to lose electrons

Atoms tend to gain, lose, or share electrons to achieve a full valence shell. For atoms with valence electrons 1-3, it is energetically more favorable to lose electrons and drop to the lower full occupied shell then to gain electrons to complete an octet in the partially filled higher shell. For atoms with 5-7 valence electrons, it is more energetically favorable to gain additional electrons for an octet as it is so close already.

Open System

Both heat and matter can be exchanged with surroundings.

Balance this equation C12H22O11 + O2---> CO2 + H2O + heat

C12H22O11 + 12 O2---> 12 CO2 + 11 H2O

Stoichiometric mole ratios and molarity

Can be used to assess the moles in an aliquot of solution.

Temperature dependence on solubility and the common ion effect

Can be used to assist in selectively precipitating compounds during separations of mixtures

Infrared Spectroscopy (IR Spectroscopy)

Can be used to detect structural changes within molecules during chemical conversions by monitoring successive sample spectra for the emergence or disappearance of peaks that are unique to a given structural feature of a molecule. For instance determine between Cis or Trans

Catalysts

Can change the rate of the reaction by lowering activation energy by stabilizing the high energy transition states. Catalysts cannot change the spontaneity (∆G, ∆H, ∆S, or T) or the amount of product produced.

Coordination Complexes

Consist of central metal ions surrounded by ligands which are bound to the metal center by coordinate bonds. Ligands act as a LEWIS BASE(electron donor) and the metal center acts as LEWIS ACID (electron pair acceptor).

Reactions that go to completion do what?

Consume all intermediates produced before or during the final step. They also must have the same number of each type of atom on left and right side of rxn arrow. Ex: Step 1 (O2 --> 2O) Step 2 (2O+ 2O2 --> 2O3) Essential that there is that 2 infront of Oxygen to add them to get product... Net Rxn ( 3O2 --> 2O3)

Conversion from mass of a substance to volume of a sample

Convert solute units to match units of mass, Then divide by the solution concentration. Always start with mass or volume given

Small electronegativity promotes what kind of bond formation?

Covalent bond formation

Polyatomic Ions

Covalentally bonded groups of two or more atoms that HAVE a net formal charge. If the total # of electrons exceeds # of protons it will be negatively charged (and visa versa) ex: SO3^-2 sulfite anion protons exceeded by two electrons

What happens to equilibrium if you add Cu2+(NO3)2 to a solution of CuF2 thats trying to be dissolved in H2O?

CuF2<-> Cu2+ + 2F- is the normal formula, so if you add Cu2+(NO3)2 that will contribute more Cu2+ ions, shifting equilibrium to the left side resulting in less dissolution and more precipitate

ionic radii group trend

Decreases in size across a period (L->R) Increases down a group (Top-> bottom)

Common Ion Effect

Decreases solubility of an ionic compound by adding more of that same Ion. Ex: Have CuF2, and add more F- results in decreased solubility as it makes eq favor the reactants.

Change in Gibbs Free Energy

Delta G = - R(T)ln(Ka) or Keq = [-A][H+]/[HA] If T or Ka increases? Delta G DECREASES

Change in Gibbs free energy equation

Delta G = Delta H - T (Delta S) T is temperature in KELVIN (never negative) Delta G is the spontaneity of a reaction Delta H is the enthalpy/ energy of a reaction Delta S is the entropy/disorder of a reaction

In order for. reaction to be endothermic and spontaneous, what must be true?

Delta G is negative, Delta H must be positive, then Delta H also must be less the (Delta S x Time )

Formal Charge

Distribution of charge to the atom in a lewis structure based on bonding configuration # of valence electrons - ( # dots + # lines)

Pauli Exclusion Principle

Each orbital within a sub shell can hold maximum of two electrons, which must have opposite spins

Nuclear Charge

Each proton in the nucleus of an atom contributes one unit of positive charge that exerts an electrostatic attraction on the negatively charged electrons around the atom. In atoms with several electrons, core electrons positioned in-between the nucleus and valence electrons provide a "shielding constant, S", that counteracts part of the full "nuclear charge, Z" attracting the valence electrons. As a result the valence electrons experience an "effective nuclear charge, Zeff" that is less then full nuclear charge. Zeff = Z -S S equals # of core electrons Z is the number of protons Ex: effective nuclear charge of Flourine? It has 2 shells, first shell contains 2 CORE electrons, second shell can hold up to 8 valence electrons, but since fluorine has 9 e/p's the valence shell only holds 7 electrons. This means Z = 9 and S = 2 so Zeff= 7. (1s2 2s2 2p5) Effective nuclear charge of Al? 3 shells, 13 e/p's total, so first shell holds 2 CORE electrons, second shell holds maximum 8 CORE electrons, meaning the outer "valence" shell holds 3 electrons. Z= 13 S = 10 Zeff = 3 to determine the number of core electrons, do total number of electrons (equals total # of protons) minus valence electrons present.

Hund's Rule

Electrons fill orbitals in such a way as to maximize the # of unpaired electrons

Representative Elements

Elements in groups 1, 2, 13, 14, 15, 16, 17, and 18. Everything except transition metals

Do elements directly to the left or right share similar chemical properties (same row or period)? Or do elements directly above/below (same column or group)?

Elements in the same column/group have more similar chemical properties because they all share the same configuration of valence electrons. ex: Ti, and Zr both have 4 valence electrons so are more similar then Ti and V

Alpha Decay

Emission of an alpha particle (contains 2 neutrons and 2 protons). Resulting nucleolus will have an Atomic Weight four less then original, and an Atomic Number 2 less then original. Ex: Alpha particle ejected 94 -2 92 Pu -Alpha Decay- U 244 -4 240 As long as proton number is the same it is still classified as that element. Atomic mass isn't as important Has a 2+ charge, most harmful

Reactions with positive Enthalpy (delta H) are endo or exothermic?

Endothermic. Heat makes rxn go from lower energy state to a higher energy state as heat is put in. Products have more energy then reactants

Positive Delta H and Delta S is what kind of reaction?

Endothermic. Rxn is spontaneous (-G) at high temperatures, non spontaneous (+G) at low temperatures.

∆H equals

Energy products- Energy of reactants. So endothermic processes have +∆H's while exothermic reactions have -∆H's

First Ionization Energy

Energy required to remove the first, most loosely bound electron from an atom of an element. Valence electrons are removed first before any core electrons b/c removing core electrons takes much more energy. Elements with loosely bound valence electrons have lower first ionization energy. Atoms with larger size have electrons bound less tightly as they occupy increasingly higher energy levels (bigger n). So typically smaller atoms have the higher first ionization and are therefor less reactive. Ex: Li is least reactive, Cs is most reactive More reactive? Easier to Ionizes Metals have a lower 1st ionization energy vs non-metals.

Second Ionization Energy

Energy required to remove the second electron from an atom of an element. Valence electrons are removed first before any core electrons b/c removing core electrons takes much more energy. Metals have a lower 2nd ionization energy vs non-metals EXCEPT when the second electron being removed is not a valence electron.

Adding Ligands that can form coordination complexes with metal ions in a solution does what?

Enhances the solubility of ionic salts. Le Chateliers principle says that this removal of the metal due to the bonding to the liana results in EQ shifting to the products. Ex: CuF2<-> Cu2+ + 2F- add ligand (CH3NH2) then.... NH2CH3 + Cu2+ <-> [Cu(NH2CH3)] so there will be less Cu and therefor EQ goes towards products = increased solubility

Catalyst affect reaction rate but don't affect...

Enthalpy (Delta H) Entropy (Delta S) Temperature (T) measured in kelvin (never negative) Equilibrium (Ka)

Double Replacement Reaction

Exchange of bonding partners between two reacting compounds and results in the formation of two new product compounds. Ex:

Similar Chemical Properties

Exist between atoms in the same group or column as they have the same number of valence electrons

Difference between exergonic and exothermic rxns? difference between endergonic and endothermic?

Exothermic and Endothermic refer to changes in enthalpy. Endothermic reactions have +∆H (gaining heat) and Exothermic reactions have -∆H (losing heat) Exergonic and endergonic rxns involve a change in the Gibbs free energy. Exergonic reactions have a -∆G as reactants have less energy then products (NRG released from reaction, kinda like releasing heat). Endergonic reactions have a +∆G as reactants have more energy then products (NRG is gained from the rxn)

Negative Delta H and Delta S is what kind of reaction?

Exothermic. Rxn is spontaneous( -G) at low temp, non spontaneous(+G) at high temps

Polar Covalent Bond

Extreme differences in electronegativity can result in unequal electron sharing which results in electrons in bond pulled closer to atom of greater electronegativity. This results in a DIPOLE moment.

Electron Affinity

Favorability to accept electrons. Change in energy when an electron is added to each atom. More energy is release when He releases an electron vs Ca Electron affinity values with a more negative magnitude indicate elements that more readily accept the addition of an electron

Charles Law

For a fixed amount of gas at a constant pressure, the volume of the gas increases as the temperature of the gas increases and the volume of the gas decreases as the temperature of the gas decreases V1T1=V2T2 bc PV = nRT

Covalent bond

Formed by shared valence electrons between two atoms (usually nonmetals)

Equilibrium is achieved in a reversible reaction when...

Forward and reverse reaction occur simultaneously at the SAME rate M=mol/l

Reduction

Gain of electrons or hydrogens

Galileo Thermometer

Has a cylinder filled with a liquid and many isolated system bulbs filled with liquid that have the same density as the surrounding fluid in the cylinder at 25 degrees Celsius. As temperature decreases, density of liquid in cylinder will increase (as same mass is occupying a contracted volume), this will then cause the isolated systems to float to the top. Same if temp increases, then density of fluid will be less then that of isolated systems and the bulbs will sink This thermometer is only useful for measuring temperatures around 16 to 34 degrees Celsius

pH = pKa + log A-/HA

Henderson-Hasselbalch equation, used to find pH of a buffer system. Eq shows that when pH of a solution is EQUAL to the pKA of a w.a., there are EQUAL amount of the w.a. and its conjugate base in solution.

Oxidation Number Rules

Hydrogen +1 Group #1 (column 1) is +1 Group #2 (column 2) is +2 Group #17 Halogens is -1 (F, Cl, Br, I) Oxygen is -2 Net charge of oxidation #'s MUST = 0 Ex: K2MnO4 K = +1 Mn= ? O = -2 sooo... K2 = +2 O4 = -8 Mn = ? +2 + (Mn) -8 = 0 Mn = +6

Ideal Gases

Hypothetical gas whose molecules occupy negligible space (no volume) and have no interactions (no intermolecular forces). Ideal gases prefer low pressure spaces as that decreases the chances they will interact with each other in a nonelastic way (as density isn't as great). Otherwise at high pressure molecular volume occupied by the gas particles becomes significant relative to the volume of the container.

Van 't Hoff Plot

If slope of line is negative that equals a positive Delta H (endothermic). Slope is positive? then Delta H is negative (exothermic)

Increasing surface area of a catalyst does what?

Increases rate of reaction

Ionic Bonds

Ion-ion interactions between two charged species. Formed between atoms when the valence electrons from one atom are transferred to another atom, resulting in charged ions held together by electrostatic attractions.

In an Isoelectric series

Ionic Radii DECREASE with increasing atomic number.

Large electronegativity promotes what kind of bond formation?

Ionic bond formation

Length of a Sigma (single) bond

Is the sum of the atomic radii, so the bigger the radii of bonded atoms, bigger length. Radii decreases doing down and to the left of periodic table

Sulfur(F6) has what hybridization state?

It has 6 electron dense regions so it violates the octet rule and puts it in an excited state. The normal electron config of sulfur at ground state is 3s2,3p4, so it occupies 1 s orbital and 3 p orbitals. When sulfur is bound to 6 florins and is excited, then is occupies 1 s orbital, 3 p orbitals, and 2 d orbitals. sp3d2 https://www.quora.com/What-is-the-hybridization-of-SF6

If you lose some solid precipitate during filtration, how does that effect your percent yield?

It will decrease it because you will have less actual yield which will result in a smaller percent (as it is divided by theoretical mass)

2 NO2 <--> N2O4 and Keq = 8 atm. What is the pressure of dinitrogen tetroxide when pressure of nitrogen dioxide is 0.5 atm?

K eq = Products/reactant K eq = N2O4/ 2(NO2) 8 atm = N2O4/ 2(0.5) N2O4 = 2 atm

∆G increases Keq......? -∆G increases, Keq.....?

Keq < 1. (equilibrium favors reactants) and Keq > 1 ( equilibrium favors products)

Oxidation

Lose electrons, hydrogens, or gain oxygens Ex: Cu to Cu2+

Law of conservation of mass

Matter is not created nor destroyed in any chemical or physical change: Only rearanged

Electron shells can hold a maximum of how many electrons?

Max amount of electrons a shell can contain is represented by 2(n)^2. n=1 can hold 2 electrons, second shell n=2 can hold 8 electrons, third shell n=3 can hold 18 electrons and so on. 7th shell can hold 98 electrons In theory, though no element exists. Also shells won't necessarily fill up like that, typically go 2, 8, 18, 32, 32, then varies, want to stay stable

Buffer with a Ka of 1.9 x 10^-5 tells us what about its pKa (which is equivalent to pH)?

Means its pKa is 5, there for that buffer would be best to buffer a system with a pH of 5 naturually

pKa

Measure of acidity of a particular proton in a molecule. In buffer system... pH = pKa, then [HA] = [A-] pH > pKa, then [HA] < [A-] pH < pKa, then [HA] > [A-] based off: pH = pKa + log A-/HA [A-] De-protonated conjugate base [HA] undissociated acid

Calorimetry Experiments

Measure the temperature as a reaction progresses. The change in temperature ∆T can be found by subtracting the final temp (peak of graph) by initial temp (base of graph)

Ionization Energy

Measures energy required to remove an electron from an atom (opposite of electron affinity) Harder to remove electron from He vs Ca

Energy of Activation

Minimum energy that must be put in to activate the reactants sufficiently for the completion of the reaction. (minimum energy needed to reach highest energy transition state) Ea = energy difference between the highest peak and the reactants.

Ligand

Molecule that donates the necessary electrons to form coordinate covalent bonds with metallic ions

How are things detected via IR Spectroscopy?

Molecules are considered IR-Active when vibrational modes produce a net change in a dipole. That will result in an absorbance peak on the spectrum.

Delta S is negative but Delta H is positive is spontaneous RXN or not?

NEVER spontaneous

Exothermic Reaction

Negative ∆H b/c heat is lost by the system (released to surroundings). When ∆S is negative too the process is spontaneous(-∆G) at low temperatures and non spontaneous(+∆G) at high temperatures. When Delta S is positive the process is ALWAYS spontaneous ( -∆G)

Is the neutral covalent compound and the polyatomic ion version the same compound?

No because the # of electrons and the bonding configuration is different. Ex: SO3^-2 and SO3 have same elemental composition but different # of electrons and composition

Isolated System

No exchange of heat or matter with surroundings

Closed System

No exchange of matter but there is an exchange of heat with the surroundings

Diamagnetic

No unpaired electrons, won't interact with magnetic field

When Delta G is greater then 0 the reaction is...

Nonspontaneous

Atomic number of an element

Number of protons (at the top)

Atomic Weight

Number of protons + neutrons (at bottom)

B-Sheet formation in proteins

Occur due to strong non covalent hydrogen bonding interactions between A.A

Less Effective Nuclear Charge

Occurs when there is a gain of electrons which forms an anion. Now there is more shielding between the protons of nucleus and the valence electrons, so valence electrons feel less effective nuclear charge (or less pull) from protons.

Greater Effective Nuclear Charge

Occurs when there is a loss of electrons which forms a cation. There is less shielding between the protons of nucleolus and the valence electrons, so valence electrons feel a greater effective nuclear charge (or pull) from the protons.

Balance the following equation Ca + H2O ---> Ca(OH)2 + H2

On both sides you have 1 Ca On left side you have 2 H's, 1 O On right side you have 4 H's 2 O's to balance, multiply left H2O by 2 Ca + 2(H2O) ---> Ca(OH)2 + H2

When a polyprotic acid is titrated with a SB, it will show how many equivalence points for each acidic proton?

One equivalence point

Decomposition Reaction

One reactant species breaking down into two or more product species

Reaction Free-Energy Diagram

Plot of Gibbs free energy (y-axis) and progress of a reaction pathway (reaction coordinate (x-axis). Transition states are characterized by elevated energy, high energy maxima peaks. So every peak is a transition state. Two peaks? two transition states. Energy of Activation minimum energy needed to reach highest energy transition state in order for reaction to go to completion

Endothermic Reactions

Positive ∆H b/c heat is added to the system (absorbed from surroundings). When ∆S is positive(gain disorder) too the process is spontaneous (-∆G) at high temperatures and non spontaneous (+∆G) at low temperatures. When Delta S is negative(loss of disorder) the process isn't spontaneous (+∆G) at ANY temperature

Hybridization

Process by which two or more atomic orbitals (s, p, d, f) combine to form new hybrid orbitals that have different shapes and spatial orientations

Buffer Systems

Protective systems regulating amounts of hydrogen ions in body fluids. Made up of WA and its conjugate base, or WB and its conjugate acid. These combinations provide both acidic and basic species to counter act H+ or OH- ions from any SA or SB added to solution. Have to be in much HIGHER CONCENTRATION then amount of SA/SB added, and when this is the case it results in SMALLER CHANGE in pH

Beta Decay

Radioactive decay in which an electron is emitted, occurs in 3 forms, mass number always stays the same, atomic number (protons) varies. 1. B- decay (electron emission) - neutron converts to a proton and emits electron 226 226 Ra ---> Ac 88 89 2. B+ decay (positron emission) - proton converts to neutron and emits positron 226 226 Ra ---> Ac 88 87 3. Electron capture - proton captures electron & converts to neutron w/no positron or electron emission 226 226 Ra ---> Ac 88 87 As atomic # changes the identity of the element changes accordingly

If when reactant B's concentration is doubled the rxn rate goes up 4 times (quadrupled), and when reactant A's concentration increase by 1.5, the rxn rate increases by 1.5 as well, this means the expression for the rate of this reaction is...

Rate = k[A][B]^2 (third order rxn)

Rate Equation

Rate = k[A]^m[B]^n K is the rate constant and m and n are the orders of reaction with respect to that specific reactant 2nd Order reactions k[A]^2[B]^0 k[A]^1 [B]^1 1st Order reactions k[A]^1[B]^0 k[A]^0[B]^1 3rd Order reactions k[A]^2[B]^1 k[A]^1[B]^2 k[A]^3[B]^0 k[A]^0[B]^3 etc. Anything to 0 power equals 1

Limiting Reactant

Reactant that is completely consumed first. Usually has smallest amount of moles.

Single Replacement Reaction

Reaction of a compound with a free element and leads to formation of a new compound and new element as a product

Disproportionation

Redox reaction in which both the oxidation and the reduction occur with atoms of the same element. Compare oxidation #'s to tell wether this occurred. Oxidation #'s will increase for elements that are oxidized. Oxidation numbers will reduce for elements that are reduced.

Sp, Sp2, Sp3

Represents the different electron density regions around an atom. Sp has 2 (triple bond + lone pair, or two double bonds), Sp2 has 3 (double bond + single bond + lone pair, or double bond + 2 single bonds, or double bond + 2 lone pair), Sp3 has 4 regions (2 single bonds 2 LP, 3 single, 1 LP, 3 LP 1 single, 4 single)

In order to separate CuCl2 and CuSO4, which Ion would you want to add to enhance the common ion effect?

SO4 or Cl2, NOT Cu b/c that is common for both so that would decrease solubility for both resulting in no difference.

Atoms with the similar chemical properties have...

Same # of valence electrons (same group/column)

Identical chemical species must have what characteristics?

Same elemental composition, the same number of electrons, and the same orbital bonding configuration.

Proper Lewis Dot Structure

Should have a total number of electrons (dots/lines) equal to total number of valence electrons with NO net charge. Ex: SO2 should have 18 electrons and no net charge

Pourbaix Diagram

Show the relationship between chemical species as a function of given conditions. Boundary lines between domains indicate the transition from one species into another, and can also indicate equilibrium between aqueous and precipitating species. Boundaries parallel to an axis show constant ranges that are independent of changes in the respective axis variable.

Compounds with larger Ksp values are more or less soluble?

Since Ksp's that are smaller are less soluble, larger Ksp's are more soluble

What happens to equilibrium if you add some acid to a solution of CuF2 in water when F- ions are mildly basic ? Keep in mind CuF2 in water doesn't dissolve easily as it favors the reactants (undissolved salt)

Since fluoride is slightly basic the little bit of F- that does dissociate will be used by the acid to form HF and the concentration of F- anion will decrease initially. H+ + F- <-> HF CuF2<-> Cu2+ + 2F- Therefor the equilibrium will want to shift toward the products to to form more F- which results in better dissolution.

How do you get a molecule with polar ends (carboxylic acid groups) but non polar hydrocarbon middle chain to dissolve in a water based solution before titration?

Since water is polar, and this molecule only has polar carboxylic acid groups at the end and a non polar hydrocarbon chain in the middle (giving it low solubility in a water based solution) we want to first dissolve this compound with a base to deprotonate the carboxylic acids converting them into a carboxylates (very basic and polar). Now that this structure is basic (basic solution), you want to titrate it with an ACID then to get to an equivalence point. By subtracting the number of moles of base in the initial solution from the number of moles of acid required to reach the equivalence point during the titration will give the number of moles of carboxylate groups present in the sample (which tells you the concentration) Normally if the acid was dissolvable in the solute, you would just titrate it with a base and indicator until equivelance point.

Ksp

Solubility product constant that measures solubility of compounds at a given temp. Smaller Ksp? Less soluble. Fewer common ions must be added to induce precipitation. Fewer moles present.

Hydrogen Bonding

Special type of non-covalent dipole-dipole interaction involving species with partial charges. Type of Intermolecular force. O-H F-H N-H

Nuclear Fission

Splitting of a large atomic nucleus into multiple smaller nuclei

When Delta G is less then 0 the reaction is...

Spontaneous

Boyles Law

States that when temperature & number of moles of gas are constant, when volume of gas is compressed, pressure increases. When volume of gas is decompressed, pressure will drop. Pressure of an ideal gas is inversely proportional to volume P1V1=P2V2 bc PV = nRT

The greater electronegativity difference between atoms results in a stronger or weaker dipole moment?

Stronger

Intermolecular Forces

Strongest 1. ion-ion 2. ion-dipole 3. hydrogen bonds (N-H, O-H, F-H) 4. Dipole-dipole 5. Dipole-induced dipole 6. Dispersion Forces

How to find unknown half-reaction when given one known half reaction and balanced net reaction?

Take balanced net reaction eq and line it above the INVERSE of the known half reaction. Balance the known half reaction if necessary, then cancel to yield the other half-reaction

Sp3

Tetrahedral 109.5 4 electron dense regions

Bent (sp3)

Tetrahedral Geometry. 2 shared bonds 2 lone pair, 104.5° 4 electron dense regions around an atom

Trigonal Pyramidal Geometry (sp3)

Tetrahedral geometry with ONE lone pair of electrons. 4 electron dense regions around an atom

Compared to a neutral atom

The Cation will be smaller (less electrons) and Anion will be Larger (more electrons)

Electron Configuration

The arrangement of all electrons within the Shells or Sub-Shells of an atom. Shells are indicated by using the quantum number (n), which relates to distance of an orbital from the nucleus. Sub-Shells are labeled by type (s, p, d, or f), which relate to shape of the occupied orbital and hold a max of 2, 6, 10, and 14 electrons respectivley. Electron Configurations are listed sequentially in order of INCREASING ENERGY.

Reducing Agents

The atom that gets oxidized is the "reducing agent" as it loses electrons/hydrogens and gives them to another atom, thereby reducing the other atom. Cause reduction to occur on other atoms meaning they remove oxygens and add electrons/hydrogen bonds

Oxidizing Agents

The atom that gets reduced is the "oxidizing agent" as it is gaining electrons/hydrogens by removing them from another atom, therefor oxidizing that atom. Cause oxidation to occur on other atoms meaning they give oxygens to other atoms or remove electron/hydrogen bonds

Thermodynamic product

The compound with the HIGHEST energy transition state which forms slowest, but is the MOST stable

Kinetic product

The compound with the LOWEST energy transition state which forms fastest. Making it the kinetic product, not as stable as thermodynamic product.

Coordination Number of Metals

The coordination number of metal complexes like copper (II)glycinate refers to how many coordinate bonds are formed. so copper (II) forms TWO coordinate covalent bonds. Coordinate covalent bonds (unlike covalent bonds) are formed between two atoms when one atom donates BOTH shared electrons. Typically these bonds are formed between electron-poor metal ions and molecules called LIGANDS that contain 1 or more electron rich atoms w/available lone pairs

Polarizability

The ease at which an atom can absorb electrons. Larger atoms have greater polarizability b/c they have a larger nucleus & electron cloud, so when the electron is absorbed, the charge has a smaller effect due to the large nature of the area.

Oxidation State

The gain or loss of electrons by an atom due to bond formation •Oxygen: -2 •Alkali metals: +1 •Alkaline earth metals: +2 •Halogens: -1 •Hydrogen: +1 (w/non-metals) -1 (w/metals)

Enthalpy

The heat energy a reaction contains. Higher enthalpy? Need more energy to make reaction occur (like break a bond) and less thermodynamically favorable (non-spontaneous) as... ∆G = ∆H - T∆S ∆H If a photon laser has to break something with 456 ∆H, then its Energy (E=λf) must be greater then 456 ∆H. If its not? Then must increases frequency.

Equilibrium Constant

The molar ratio of products to reactants when system is at equilibrium. Keq = Products/Reactants

Gamma Decay

The release of gamma rays (Photons) from a nucleus. Doesn't change atomic number or mass. Gamma photons have no charge, so least harmful

Rate Limiting

The step that must overcome the largest energy barrier to pass through the transition state.

Standard Reduction Potential

The tendency of a species to be reduced. Larger positive E means larger standard reduction potential which is thermodynamically favorable (Delta G < 0)

If a solution contains two salts that have an ion in common, what affect does that have on the equilibrium?

This produces a common ion effect that shifts the equilibrium to the left (reactants) so solubility DECREASES

Bent Geometry (sp2)

Three atoms bond in a nonlinear arrangement. 1 lone pairs. 3 electron dense regions around central atom

Dalton's Law of Partial Pressures

Total pressure of a mixture of gases is equal to the sum of the partial pressures of each of the gases within the container. Use the percent of gas (or mol fraction) times the total pressure of the container to determine partial pressure of that gas.

Combination Reaction

Two or more chemical species reacting to combine and form one product species

Electron Capture

Type of Beta Decay where nucleus absorbs electron. (Proton converts to neutron) 38 to 37

Dipole-dipole interactions

Type of non covalent intermolecular force that occurs between neighboring polar molecules with polar bonds and a net dipole moment. Molecules align in a way such that the partial negative charges orient toward partial positive charges

Dissociation Reactions

Typically endothermic process as heat needs to be added to system. The smaller broken apart products have more energy then reactants

Rule for log

Unless told otherwise, log(#) means log10(#) for example... log10(100) means what exponent on 10 will give you 100? In this case 10^2 = 100 so log10(100) = 2 log of a decimal = negative number & smaller decimal = bigger negative number log(0.001) = -3 log(0.99) = -0.004 log of a whole number = positive number & bigger whole # = bigger # log(1) = 0 log(2) = 0.301 log (500) = 2.69

Given the pKa of a reaction (6.8) and the molarity of the two reactants HPO4^-2 (0.5 M) + H+ ⇄ H2PO4^-1 (5.0 M) What will the final pH of the system be?

Use Henderson-Hasselbalch equation to solve for pH of a buffer system. pH = pKa + log A-/HA pH = 6.8 + log 0.5/5 = 6.8 + (-1) = 5.8 Buffer solution is made of weak acid and its conjugate base.

Indicator

Used in Acid-Base titrations to determine the endpoint of a titration. Compound changes color close to the equivalence point (point where stoichiometric amount of titrant needed to consume all acid or base has been used). They do NOT participate in the reaction so they DON'T change the pH ex: bromothymol blue

How can the atomic weights (protons and neutrons) of resulting nuclei of nuclear fission be measured and correlated?

With their atomic numbers (# of protons)

Determining Delta G from the slope and y-intercept of a van't Hoff plot

Y = m(x) + b lnKa = -(Delta H/R)(1/T) + (Delta S/R) Y = lnKa m = -(Delta H/R) x = (1/T) b = (Delta S/R) so if they tell you the slop and y intercept, you know Delta H and Delta S which you can use to find Delta G. Ex: slope is 5 and y int is 4, what is delta G? Delta G = -5R - T(4R)

Which of the following is the electron configuration of a Ca2+ ion? 1. [Ne]3s^2 2. [Ne]3s^2, 3p^6 3. [Ne]3s^2, 3p^6, 4s^1 4. [Ne]3s^2, 3p^6, 4s^2

[Ne] 3s^2, 3p^6 [Ne] is the abbreviation for the first 10 electrons configuration (1s^2, 2s^2, 2p^6) which is identical to Neons. So calciums full electron configuration is normally [Ne] 3s^2, 3p^6, 4s^2. During ionization however, electrons in the highest energy shell/subshell are lost first, so Ca2+ (indicating loss of two valence electrons) would come from the 4s shell.

Single Replacement Reactions

an element replaces an element in another compound (AB+C -> CB+A). A compound and a new neutral element are produced. Ex: HCl + Al ---> AlCl + H

Combustion Reaction

an exothermic chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light

Avagadro's Law

at constant pressure and temperature, the volume of a gas is directly proportional to the number of moles of the gas present V1n1 = V2n2 bc PV = nRT

When Delta G = 0 then the reaction is...

at equilibrium

Period is to row, as group is to...

column of periodic table

Overall Reaction

describes the reaction stoichiometry and is a summation of elementary reactions Ex: H2O2 + I- --> IO- + H2O H2O2 + IO- --> H2O + O2 + I So overal reaction is 2(H2O2) --> 2(H2O) + O2

Exothermic phase changes

freezing (liquid->solid), condensation (gas->liquid), deposition (gas->solid), all release heat into surroundings. Involves bond formation or increase of intermolecular interactions (gives off energy b/c free gas has more energy then a solid so when deposition occurs products have less energy then reactants) Anabolic RXN Spontaneous at all temperatures Delta G < 0 Delta H < 0

Thermodynamic values tell you what?

if the reaction is spontaneous or not but they don't indicate the rate of a reaction b/c G S H and T are independent of reaction mechanisms.

Sp

linear (usually has triple bond) 2 electron dense regions

Endothermic phase changes

melting (solid to liquid), vaporization (liquid to gas), sublimation (solid directly to gas), all require the input of heat from surroundings. Involves breaking of bonds or intermolecular interactions (needs heat/energy from surroundings) Catabolic RXN Non spontaneous unless high temperatures Delta G > 0 Delta H > 0

Linear Geometry (sp)

no lone pairs, 2 bonds, 180 triple bond or two double bonds 2 electron dense regions around central atom

d2sp3

octahedral, square pyramidal, square planar 6 electron dense regions (excited state)

Delta G decreases (increasing spontaneity) when....

pH decreases or (T and Ka increase)

Polyprotic Acid's pH at the first equivalence point is determined by which of the following? pKa1 pKa1 & pKa2 pKa1, pKa2, and pKa3

pKa1 & pKa2. pH at the equivalence point for a monoprotic acid is equal to pKa1, but polyprotic acid is between pKa1 and pKa2

Tetrahedral Geometry (sp3)

the molecular geometry of five atoms with 109.5 degree bond angles. 4 electron dense regions around an atom

Trigonal Planar Geometry (sp2)

the molecular geometry of four atoms with 120 degree bond angles and NO lone pairs 3 electron dense regions around central atom

Gay-Lussacs Law

the pressure of a gas is directly proportional to the Kelvin temperature if the volume and number of moles is constant T1P1=T2P2 bc PV = nRT

Van Der Waals Forces

the two weakest intermolecular attractions- London dispersion interactions and dipole forces. London dispersion forces are larger in larger molecules with larger, more polarizable electron clouds

Stronger Lewis bases tend to be...

those that have lone pair electrons on atoms with a net charge and/or lower electronegativity (down and to the left)

dsp3

trigonal bipyramidal, see-saw, t-shaped, linear 5 electron dense regions (excited state)

Sp2

trigonal planar 120 (usually has double bond) 3 electron dense regions

Coordinate bonds

when one atom supplies both the shared electrons to form covalent bond