AP Chemistry Review: Adrian Dingle's Crash Course

polyprotic acids

can donate >1 proton per molecule or formula unit (second or third H+ may or may not be lost with similar ease to first)

monoprotic acids

can only donate one proton per molecule or formula unit

induced dipole-induced dipole (London dispersion forces)

caused by movement of electrons within covalent bonds of molecules that would otherwise have no permanent dipole electrons temporarily displaced bc mutual repulsion increase with increasing # e- & increasing surface area --> greater polarizability, greater attraction --> higher melting/boiling points enhanced in molecules w/ pi bonds their accumulation in larger molecules can lead to them being strongest net force b/w 2 molecules

3 ways chemical equilibrium can be disrupted

change in temperature change in concentration of reactant or product change in volume or pressure (where gases are involved)

in regards to lattice energy trends, ____ trumps ____

charge size

oxidation states (/#s)

charges that an atom actually has when in an ionic compound, or when in a molecular compound, charge that atom would have if compound were ionic

indicator

chemical (often weak acid itself) that changes color over a narrow pH range

metal's bonding and structure can be considered a

close-packed lattice of positive kernels, surrounded by a "sea" of free-moving valence electrons

observing shifts in equilibrium

color change --> in reactions where reactants and products have different colors, color of equilibrium mixture can give clues to relative proportions of reactants and products change in pH --> in reactions with H+ or OH-, shifts can be detected by monitoring pH

strong acid/base

complete ionization (dissociation) in water (considered to be 100% ionization with no reverse reaction) to produce large #s H3O+ and OH-, respectively

standard electron reduction potential

measure of reduction potential of individual half-cell when compared to SHE (always at STP)

metallic oxides are often stable, but a few decompose when heated to form

metal and oxygen gas Ex: 2HgO(s) --> 2Hg(l) + O2(g)

metallic chlorates, when heated, decompose to form

metal chloride and oxygen gas Ex: 2KClO3 (s) --> 2KCl(s) + 3O2 (g)

metallic carbonates, when heated, decompose to form

metal oxide and carbon dioxide Ex: Li2CO3(s) --> Li2O (s) + CO2 (g)

metallic hydroxides, when heated, decompose to form

metal oxide and water Ex: Ca(OH)2 (s) --> CaO(s) + H2O (l)

alloys

mixtures of metals typically good conductors, since, like pure metals, still have a sea of free-moving electrons

2 lone electron pairs around central atom; 5 groups formula: AX3E2

molecular geometry = T-shaped Ex: ICl3

2 lone electron pairs around central atom; 4 groups formula: AX2E2

molecular geometry = bent or V-shaped Ex: H2O

3 lone electron pairs around central atom; 5 groups formula: AX2E3

molecular geometry = linear Ex: XeF2

0 lone electron pairs around central atom; 2 groups formula: AX2

molecular geometry = linear bond angle = 180 Ex: CO2

0 lone electron pairs around central atom; 6 groups formula: AX6

molecular geometry = octahedral bond angle = 90 Ex: SF6

1 lone electron pairs around central atom; 5 groups formula: AX4E

molecular geometry = seesaw Ex: SF4

2 lone electron pairs around central atom; 5 groups formula: AX4E2

molecular geometry = square planar Ex: XeF4

1 lone electron pairs around central atom; 6 groups formula: AX5E

molecular geometry = square-pyramidal Ex: BrF5

0 lone electron pairs around central atom; 4 groups formula: AX4

molecular geometry = tetrahedral bond angle = 109.5 Ex: CH4

0 lone electron pairs round central atom; 3 groups formula: AX3

molecular geometry = trigonal planar bond angle = 120 Ex: BF3

0 lone electron pairs around central atom; 5 groups formula: AX5

molecular geometry = trigonal-bipyramidal bond angles = 90, 120 Ex: PF5

1 lone electron pairs around central atom; 3 groups formula: AX2E

molecular geometry= bent or V-shaped Ex: SeO2

1 lone electron pairs around central atom; 4 groups formula: AX3E

molecular geometry= trigonal pyramidal Ex: NH3

attraction of electrons to nucleus is dependent upon:

nuclear charge (how many protons present) shielding effect of inner electrons (extent to which inner electrons protect outer electrons from nuclear charge) combined as effective nuclear charge (Zeff) =(positive charge of nucleus) - (shielding effect of electrons)

end point

observable point at which indicator changes color

large jumps in successive ionization energies for a single element are observed when passing from..

one quantum shell to another ...new shell..closer to nucleus and with less shielding..

***SINCE Kw varies with TEMPERATURE, at other temperatures, pH Of water will be a value ____ 7, but there will still be equal concentrations of H3O+ and oH=

other than as such, define neutrality in terms of there being equal concentrations of H3O+ and OH- rather than in terms of a particular pH value

half equivalence point

pH = pKA

strength of an acid and a base can be determined by the

percent of ionization

as gas expands inside a cylinder, its particles will collide with a piston and energy will be transferred from gas --> Piston...as a result...

piston moves when energy transferred in this way, gas is said to be "doing work" on piston

mass spectrum

plot of charge/mass ratio on x-axis, compared to relative abundance or intensity on y-axis a peak indicates existence of isotope with that mass relative height consistent with relative abundance of isotope) diatomic peaks exist! can be used to calculate average atomic mass of element by using masses of isotopes in a weighted average calculation

cooling curve

plot of temperature against time (at constant pressure) that result when cooling a gaseous substance, through its condensation and freezing points, until it becomes a cold solid

heating curve

plot of temperature against time (at constant pressure) that results when heating a solid substance, through its melting and boiling points, until it becomes a hot gas

oxy-acids, when heated (and sometimes w/o need for heat), decompose to form

water and non-metal oxide Ex: H2CO3 (aq) --> H2O (l) + CO2 (g)

strong acids have correspondingly _______ conjugate bases

weak (and vice versa) (stronger the acid, weaker the conjugate base)

buffers usually consist of

weak acid and its conjugate base (a salt), or weak base and its conjugate acid (a salt0

*****for a strong and weak acid of same pH, more base will be required to neutralize weak acid, since to have same pH as strong acid, ....

weaker acid must be more concentrated

diamagnetic

when a species has only pair electrons and is not attracted by external magnetic field

paramagnetic

when a species has unpaired electrons present and will be attracted by externally applied magnetic field

excited state

when an electron is promoted to a higher energy level than ground state man yare possible, depending on extent to which ground state electrons absorb energy

Common application of Dalton's Law

when collecting a gas over water in apparatus, gas evolved from chemical rxn in a flask...displaces water..is collected at top of gas jar as water is pushed out, some of water forms a vapor itself...--> small, additional pressure is exerted in the gas jar (collected gas contains both gas of interest and small amount of water vapor) in order to find pressure of gas from chemical rxn alone..must substract small water vapor pressure from total pressure

If E° -, ∆G°

+ and reaction is NOT favored

amphiprotic substances

can act as an acid or a base Ex: H2O, HCO3-, H2PO4-

all chemical reactions involve ____ of bonds

making and breaking

catalysts do not affect equilibrium position, only ___ at which it is achieved

speed

formal charge =

# valence electrons - (# nonbonding electrons + 1/2 # bonding electrons)

indicator must be chosen that changes color at a pH as close to ____ as possible

equivalence point

Why do reactions occur?

1. formation of a precipitate 2. formation of a gas 3. transfer of electrons (REDOX reaction) 4. formation of water from H+ and OH- (acid-base reaction)

entropy of a perfect, pure crystal at 0K

=0 all entropies for individual substances above 0K --> positive

when pH > pKA, [A-] ___ [HA]

>

synthesis reactions

A + B --> AB metal + non-metal --> binary ionic compound non-metal + non-metal --> binary covalent compound compound + compound --> compound

*** Molar Mass =

(mass x R x T) / (P x V)

If E° +, ∆G°

- and reaction is favored

pKa =

-log Ka

general principles of calorimetry

-put chemical rxn or phase change in contact with a heat bath (usually water) -measure change in temperature of heat bath -knowing heat capacity of heat bath, can calculate energy change in heat bath with q = mC energy change when 1 mol of substance converted from solid to liquid where solid melting, amount of energy that is added can be calculated using: q= mCΔT -energy change in heat bath will be same magnitude in energy as chemical rxn or phase change, just with opposite size

in first order reaction, in graph of time vs. ln concentration, k =

-slope

in zero order reaction, in graph of time vs. concentration, k =

-slope

5 Postulates of Kinetic Molecular Theory

1) KE (energy of motion) of a gas is directly proportional to Kelvin temperature --> the higher the temperature, the greater the kinetic energy of gas particles KE = (1/2) mass x velocity^2 2) Gases consist of particles whose volume is negligible compared to volume of container, i.e., gas particles themselves effectively occupy zero space 3) gas particles are in continuous, random, and rapid motion 4) gas particles collide with each other and walls of container --> during these collisions, no energy is lost, i.e., they are elastic collisions 5) gas particles do not attract one another, i.e., effectively, each gas particle moves indepedently

Valence Bond Theory

1. Bonds formed by overlap of atomic orbitals -Orbitals overlap to form bonds between atoms - One electron from each of bonded atoms accommodates overlapping orbital -Both electrons in overlap are attracted to nucleus of each atom--> this is why electron pairs are located between 2 atoms in Lewis structure 2. Sigma bonds formed when overlap along internuclear axis of bond 3. Pi bonds occur in double and triple bonds --> sideways overlap occurs above and below internuclear axis of bond 4. sigma bonds generally stronger than pi bonds --> larger bond energies -however, multiple bonds contain a combination of sigma and pi bonds --> shorter and stronger than sigma bonds alone

Manipulation of Equilibrium Constant

1. Multiplying chemical equation by a coefficient --> raise K to that power 2. reverse equation --> 1/K 3. if balanced chem equation produced by combination of other equation, new value of K: Knew = K1 x K2 etc.

Collision Theory

1. Reacting molecules must collide with each other 2. Reacting molecules must collide with sufficient energy (Ea) . Ea is energy barrier that must be overcome before a reaction can take place 3. Reacting molecules must collide with a specific geometry/orientation to allow rearrangement of reactant bonds into product bonds 4. "successful" or "effective" collisions have both sufficient energy and correct orientation to allow them to lead to a reaction 5. "unsuccessful" collisions lack sufficient energy and/or correct orientation, and, therefore do not lead to a reaction 6. in most reactions, only a small % of collisions are "effective"

tips to balance equations (don't have to follow!)

1. first balance metals, then non-metals 2. balance hydrogen and oxygen last 3. balance polyatomic ions as units 4. be sure to balance charges (and put all coefficients in lowest possible integers IF IONIC)

VSEPR (Valence Shell Electron Pair Repulsion)

1. VESPR is a model used to predict shapes of covalent molecules + polyatomic ions from Lewis diagrams 2. VESPR is based upon valence shell electrons repelling each other (via repulsive Coulombic interactions) so that they are as far apart as possible ---> minimize repulsion

Types of catalysts

1. acid-base: a PROTON is lost or gained by a reaction, which results in a change in rate of reaction 2. SURFACE: ex--> gases may be absorbed onto surface of metal where reactant bonds are weakened --> reaction occurs faster; also collecting reactants onto common surface in smaller area effectively increases [reactant] --> increases rate 3. ENZYME: biological catalysts with active sites that interact with substrates (reactants) to increase rate of reaction

**pH depends upon these 2 independent factors:

1. degree of ionization --> whether acid is strong or weak and produces many or few H+ ions 2. concentration of solution --> how much H2O is present

catalyst

1. increases rate of reaction by lowering activation energy of an elementary step...but leaves mechanism unchanged 2. increases rate of reaction by forming new reaction intermediate and, therefore, a new reaction mechanism that happens to have a lower activation energy present at start of rxn and not consumed during reaction often react and change during reaction, but ultimately change back into original format, are regenerated, and so are not consumed

factors related to collision theory

1. increasing surface area of a solid reactant can increase rate by increasing # of collisions 2. a rise in temperature will increase average KE of particles, thus allowing more collisions b/w reactants; net result is to increase rate of reaction -as average KE of particles increases. # of particles that possess required Ea also increases

conditions that can affect rate

1. increasing surface area of a solid reactant can increase rate by increasing # of collisions b/w reactant particles 2. catalyst increases rate by lowering activation energy of a reaction 3. increasing temperature results in a faster reaction; rate constant is temperature dependent and a rise in temperature will increase rate constant 4. concentration of reactants increases amount of reactants colliding with each other, thus yielding product

observations to ID physical/chemical change

1. seeing a color change 2. seeing a solid (precipitate) being formed 3. observing an energy change in form of light or heat

enthalpy change for dissolution is dependent upon (and a sum of) 3 independent factors:

1. separation of solute particles from one another (endothermic) 2. separation of solvent particles from one another (endothermic) 3. interaction b/w solute particles and solvent particles--> ex: ions becoming hydrated when ionic substance dissolves in H2O (exothermic)

3 separate processes take place when a solution is made:

1. solute particles must separate from one another (bonds break, endothermic) 2. solvent particles must separate from one another (bonds break, endothermic) 3. solvent and solute particles must interact (bonds form, exothermic) energy change depends on magnitude of each part)

Gravimetric analysis

1. uses formation of a solid and a balanced chemical equation to allow quantitative analysis of a dissolved analyte Ex: (Ag +) + Cl- --> AgCl addition of excess, Ag+ (aq) (often as silver nitrate) --> Cl- precipitate out --> solid that can be filtered, dried, and massed knowing mass + atoms must be conserved and that chemical equations show ratio of moles --> composition of original sample 2. titration technique uses a titrant (w/ known concentration) being added to analyte up to equivalence point equivalence point = where analyte exactly and totally consumed by titrant end point = point at which color change is observed (accompanies equivalence point) knowing volume and concentration --> moles --> concentration total

SAFETY RULES FOR LABS

1. wear protective gear (goggles, aprons, gloves, closed-toe shoes, etc.) 2. use fume hood when appropriate (when working with volatile chemicals 3. dilute acids by ALWAYS ADDING ACID to water, not by adding water to acid 4. take care not to cross-contaminate chemicals 5. volatile and flammable substances should be heated using a water or oil bath and heating mantle/hot plate, not a naked flame 6. heat materials gently and point test tubes away from people 7. know location of, and how to use, safety equipment

deviations from ideal behavior (real gases)

1.ideal behavior with low pressure and high temperature 2. when gases are put under pressure and cooled (move toward condensation into liquids), deviations from ideal behavior are observed --> real 3. assumptions of KMT regarding gas particles occupying a negligible volume compared to whole, and there being no attractions b/w particles, both begin to fail...and ideal behaves more like real gas 4. larger the gas particles + stronger the IMFs b/w gas particles...greater the deviation from ideal behavior

orbitals have increasing energies, with ___ having the lowest energy

1s...2s next...so on

LABS: Errors

2. minimize by repeating experiment and measurements and averaging results 2. % error can be calculated by applying following formula: % error = I experimental value - actual value I/ actual value x 100

1 mol of any gas at STP occupies a volume of

22.4 L

when pH , pKA, then [A-] __ [HA]

<

diffusion

the process by which a homogeneous mixture is formed by random mixing of 2 different gases

decomposition reactions

AB --> A + B (reverse of synthesis) thermal decomposition (using heat to cause decomposition)

flexibility of metallic bonds (can be deformed w/o changing general structure around each kernel) makes metals

malleable and ductil

effusion

the process in which a gas escapes from a vessel by passing through a very small opening

**Manipulating Reaction Conditions to Optimize Yield

Consider: N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH = -92 kJ/mol 1. Le Chatelier's principle predicts high pressure will produce more products, but high pressure can be expensive to achieve 2. Le Chatlier's principle predicts low temperature will produce more products, but low temperature can mean slow reactions 3. Compromise must be reached in order to achieve decent yields in a cost-effective and timely manner

specific heat capacities for different phases of same substance are

DIFFERENT Ex: ice, water, and steam all have different Cs, despite all being H2O

when a solute dissolves, ___ increases

ENTROPY (disorder) It is CUMULATIVE effect of enthalpy and entropy at a given temperature that determine ΔG and, ultimately, thermodynamic favorability of any dissolution process

strong bases

G1 + G2 hydroxides

Strong bases

G1 + most G2 hydroxides

Strong acids

HCl HBr HI HCLO4 H2SO4 HNO3

strong acids

HCl HBr HI HNO3 H2SO4 HClO4

solubility is ___ pH dependent

HIGHLY

pH of a buffer can be calculated using

Henderson-Hasselbalch equation

a plateau region represents stage where 2 phases are

IN EQUILIBRIUM with one another

**ONLY circumstance where strong acid would not be 100% ionized

If acid were so concentrated that # H2O molecules present were insufficient to allow ionization of every acid molecule

units for entropy

J/K mol

ONLY a temperature change will result in a change in the value of

K other changes may cause there to be more reactants or products--> will affect Q, but if temp is constant, then K is constant...equilibrium will always shift in order to bring Q and K back into equality with one another

always ___ axes and place a title on graph

LABEL

nonpolar covalent bonds are formed by ____ potential energy between atoms

MINIMIZING

in both diffusion and effusing, larger molecules travel

MORE SLOWLY!!

pure solids and pure liquids are ___ placed into expression

NOT

"cell diagram"

NOT a picture of apparatus! a nomenclature convention that always shows oxidized species on left and reduced species on right, separated by double line that represents salt bridge

expression Kp indicates that partial pressures are used (often in atm) and ___ are included

ONLY GASES

Combined gas law

P1V1/n1T1 = P2V2/n2T2

density =

PM/RT (where M= molar mass)

Work =

PΔV P = external pressure gas is working against ΔV = change in volume of gas as work is done, gas loses energy and piston gains energy..energy must be conserved --> energy lost by gas = in magnitude to energy gained by piston ****1 L atm = 101.3 J****

molten compounds will decompose into their elements via

REDOX reaction

relative thermodynamic favorability of dissolution of a salt is determined by ____ of ΔG, which depends upon both ____ and ___

SIGN enthalpy + entropy

the larger the Ka, the ___ the (weak) acid

STRONGER

**Like all equilibrium constants, Kw is ___ dependent

TEMPERATURE at 298 K, Kw = 1 x 10^-14 and pKw = logKw=14=pH + pOH

combining a nonspontaneous rxn with a TF reaction, via their common intermediates, can lead to a

TF process overall (coupling)

when average KEs are the same, ___ is reached

THERMAL equilibrium

LABS: What is the composition of an alloy?

What is this about? Analysis of an alloy using Beer-Lambert law What do I need to know? Alloys are mixtures of metals alloy can be dissolved in an ACID to produce a solution of metal IONS and if resulting solution is colored, it can then be analyzed using Beer-Lambert law Sample Q (230): Write equation to show rxn/ID type --> REDOX

LABS: How does concentration of a colored solution relate to absorbance?

What is this about? Beer-Lambert law and relationship b/w concentration of a colored solution and amount of light that it absorbs What do I need to know? A = a b c linear relationship b/w A and C optimum wavelength to use in a colorimeter or spectrophotometer is that of complementary color to color of solution (aka color that gives highest absorbance) procedure for diluting solutions including appropriate glassware (buret, pipet, volumetric flask); procedure only useful for colored solutions, often those of transition metals What might I be asked? procedure and calculations associated w/ dilution, including use of appropriate glassware and order of mixing to plot or interpret a graph of absorbance vs. concentration to select appropriate wavelength of incident light Sample Question: Why are solutions of NaCl and MgNO3 unsuitable for analysis via colorimeter in a Beer-Lambert law experiment? Answer: both solutions are colorless and, as a result, their absorbance will not vary with concentration of solution

LABS: What makes a good buffer?

What is this about? Buffers What do I need to know? What a buffer is How a buffer works and how to write equations to show buffering action factors that affect a buffer's capacity factors that affect a buffer's pH where solutions are buffered in relation to titration curves definition of polyprotic acid pH = pKa halfway to equivalence point What might I be asked? to interpret or sketch a titration curve in terms of buffering action possible when a weak acid or weak base is titrated with a strong base or strong acid to perform calculations using H-H to ID pH at equivalence points of various titration curves sample q - which makes best buffer --> weak acid and conjugate base

LAB: What are components of mixture that makes up a food dye?

What is this about? Chromatography as a separation technique What do I need to know? Chromatography involves a moving phase and a stationary phase, and separation depends on components affinity for one or other how to calculate an Rf value What might I be asked? to interpret a chromatogram to analyze a mixture to calculate a Rf value to outline procedure for a simple chromatography experiment to choose an appropriate solvent to separate a mixture based on polarities Sample Q: When comparing Rf values of 2 components of a mixture on a single chromatogram, what does a large Rf value for one of components tell us? Answer: The larger the Rf value, the further the component traveled with solvent --> component with larger Rf value has either a higher affinity for moving phase or lower affinity for stationary phase

LABS: What is the energy change during the process of dissolving a salt in water?

What is this about? Enthalpy of reaction and calorimetry What do I need to know? Application of q = mC delta T relationship b/w q and enthalpies measured in kJ/mol procedure for calorimetry energy changes associated with dissolving an ionic solid certain glassware offers certain degrees of precision What might I be asked? To design an experiment (including selection of concentrations and volumes of solutions) in order to collect temperature change data and convert that data to energy measurements to apply equation to select glassware based upon accuracy and precision required

LABS: What causes equilibrium position to shift?

What is this about? Le Chatelier's principle What do I need to know? Le Chatlier's principle and predicting how changes in conditions (stresses) affect position of an equilibrium macroscopic observations can be used to determine shift in equilibrium position What might be asked? to predict or explain shifts in equilibrium when changes in temperature, concentration, pressure, or catalysts are applied to a reaction and to be able to explain each in terms of Le Chatelier's principle to interpret particulate diagrams that show relative # species as a function of equilibrium position...pg. 239

LABS: How can we quantitatively analyze substances using a REDOX reaction?

What is this about? REDOX reactions and their analysis via titrations What do I need to know? Definition and understanding of oxidation and reduction How to write and combine half-reactions common oxidizing and reducing agents and their half-reactions a procedure for titration What might I be asked? to write half-reactions to combine half-reactions to perform calculations relating to titration data Sample Q: When using potassium manganate (VII) as titrant in titration of a solution of iron (II) ions, what is observed at end-point? A permanent light pink color caused by final drop of manganate (VII) solution being in excess after iron (II) ions have been exhausted

LABS: Separation of mixtures

What is this about? Separation techniques based upon solubility of components Intermolecular and intra forces What do I need to know? Ionic salts will tend to dissolve in polar solvents such as water large, covalent molecules (often organic)will tend to dissolve in nonpolar (often organic) solvents simple filtration techniques simple liquid-liquid separation techniques including knowledge of a separating funnel and its use basic, gravimetric analysis including filtering, drying, and massing What might I be asked? to interpret mass data collected via gravimetric analysis to predict in which layer various components of a mixture might dissolve Sample Q: During gravimetric analysis, why is it important to fully dry, but not excessively heat, solids that are collected by filtration of an aqueous solution? Answer: if solids are not completely dry, they will include water, and massing them will lead to anomalously high values being recorded; excessive heating could cause unstable solids to decompose, causing a mass to be recorded that is too small

LABS: How can we determine concentration of an aqueous ion in solution?

What is this about? Stoichiometry, and prediction of, precipitation reactions What do I need to know? Solubility rules theory of double displacement precipitation reactions, and how to write a net ionic equation simple stoichiometry of solutions PROCEDURES for simple gravimetric analysis including adding excess reactant to ensure all target ions are precipitated, correct filtering procedure, and need for washing, drying, and careful weighing of precipitates What might I be asked? to select an appropriate ionic solution to precipitate ion that has to be analyzed write full, ionic, and net ionic equations procedure for precipitation stoichiometric calculations relating to concentration, volume, mass, moles, and percentages Sample Question: Write net ionic equation for reaction of Ba2+ with SO43- solution

LABS: What is concentration of an acid?

What is this about? The titration of an acid and a base What do I need to know? Neutralization reactions titration procedure, including washing and filling burets and pipets, and selection of indicators How to prepare a standard solution titration curves including pH and buffer implications What might I be asked? to write a neutralization equation to detail procedure of a titration (rinsing and filling burets and pipets including filling tip of a buret; using a pipet to accurately dispense analyte, and the buret to accurately dispense titrant; use of an erlenmeyr flask as reaction vessel; addition of few drops of suitable indicator; potential for use of white tile to help observe end point) to perform calculations relating to concentration, volume, and pH (H-H) Sample Q: In titration of strong acid using a strong base as titrant, student uses an indicator that changes color at a pH of ~2. What effect does that have on volume of titrant added to flask? too little will be added; end point will occur long before equivalence point of ~7

LABS: What do titration curves tell us about reactions?

What is this about? Titration curves of weak and strong acids and bases What do I need to know? shapes of titration curves for any combination of weak and strong acids what dominant species are in solution at all points on curve that when dealing with weak acids and weak bases in titrations with strong acids and strong bases, respectively, that buffer solutions are produced henderson-hasselbach equation difference between equivalence point and endpoint What might I be asked? to sketch and interpret titration curves to relate titration curve to pH and pK a values to ID dominant species at any point to be able to draw particulate diagrams to demonstrate knowledge of the above to perform titration calculations

LABS: What affects pH and capacity of a buffer?

What is this about? capacity and pH of buffers What do I need to know? How to interpret H-H equation in terms of buffer capacity and desired pH What might be asked? how to perform H-H calculations and suggest good combinations of weak acid/base conjugates, both in terms of concentrations (capacity) and ratio (pH) to achieve desired buffering activity **Sample Q: Why might it be desirable to have a buffer with approximately = amounts of weak base and conjugate acid? Answer: buffer would have approximately equal capacity to absorb any acid or base that was added to it

LAB: How can we relate bonding to properties?

What is this about? influence that bonding has on observable and measurable properties What do I need to know? general properties and characteristics associated with ionic, covalent, and metallic materials What might I be asked? to predict or explain behavior of materials in realtion to properties such as electrical and thermal conductivity, solubility in polar and nonpolar solvents, hardness, melting point, boiling point, etc.

LABS: How can we deduce a rate law experimentally?

What is this about? using initial rate and concentration data to determine a reaction rate law What do I need to know? Rate laws can be determined by the initial rate method relationship between changes of rate and orders of reaction shape and interpretation of graphs as they relate to the zeroth, first, and second order reactions What might I be asked? To interpret concentration data generatedin, for example, a Beer Lambert law experiment, and to use it to determine a rate law To interpret or plot a graph to determine a rate law

LABS: How do factors like particle size, concentration, and temperature affect speed of a chemical reaction?

What is this about? Kinetics and which factors affect speed of a reaction What do I need to know? How factors such as particle size, temperature, concentration, and catalysts affect rate of a reaction; how those factors are explained at microscopic level based on chemistry concepts (collision theory, activation energy, etc. ) dilution techniques and procedures What might I be asked? to design an experiment with controls or to investigate speed of a chemical reaction (including how to measure rate of reaction) to interpret data that is generated in such an experiment including graphical representations Sample Q: Explain why using powdered calcium carbonate, as opposed to large chips of calcium carbonate, makes reaction b/w CaCO3 and aqueous HCl proceed at an increased rate Answer; greater surface area --> more collisions can take place b/w acid and solid --> increased # collisions means faster rate

LABS: How efficient are chemical processes?

What is this about? Stoichiometry, percent yield, and atom economy What do I need to know? Solubility rules, precipitation reactions, and how to write net ionic equation simple stoichiometry of solutions procedures for simple gravimetric analysis including adding excess reactant to ensure all target ions are precipitated, correct filtering procedure, and need for washing, drying, and careful weighing of precipitates; percent yield atom economy Percent Atom economy = (mass of desired products/mass of all products) x100 how to perform a calculation relating to decomposition of hydrated salts What might I be asked? to find x in formula MgSO4 . xH2O stoichiometric calculations relating to calculation, volume, mass, moles, and percentage yield, and percentage atom economy Sample q: What is meant by "heating to constant mass" in an experiment designed to analyze # moles of water present in a hydrated salt? Answer: Heating salt until all of water of crystallization has been driven off--> only anhydrous salt remains + mass of salt ceases to change

***it is possible for a very concentrated weak acid and a very dilute strong acid to have same PH, since...

[H3O+] could be same in each case in one case, [H3O+] may be primarily due to [acid], and in other due to strength of acid

weak acids are NOT completely dissociated and equilibrium that exists requires use of Ka (acid dissociation constant) to ..

calculate pH must set up ICE table to illustrate reversible reaction of weak acid, HA, with H2O

all the way up to equivalence point, excess acid or base is present, so ...

a BUFFER is created!

rate of a chemical reaction

a measure of the change in concentration of reactants or products over time...can be measured as increase/decrease in concentration per unit time

percent yield

a method to calculate effectiveness of chemical reaction = (actual yield/theoretical yield) x 100

significant figures

any nonzero integers = significant leading zeros NEVER significant captive zeros (fall b/w nonzero digits) = significant trailing zeros = significantIF # is written with a decimal point exact #s have unlimited # sig figs --> definition/counting

quantitative aspects of electrolysis

apply I = q/t to calculate charge in coulombs (q = charge in C; I = current in A; t = time in sec) convert charge in coulombs to faradays, by dividing q by 96485 C/F know that # of electrons that appear in a given half-reaction IS the # of Faradays required to complete reaction (ex: in Cu2+ + 2e --> Cu, one mol of copper is formed by passage of 2 F electrical charge and masses produced are proportional)

conjugate acid-base pairs

a pair of substances that differ in formula only by a proton (H+) all acid-base reactions involving proton transfer of 2

common ion effect and pH

a salt becomes increasingly less soluble in a solution that contains one of its ions explained through Le Chatelier's and = common ion effect Ex: some chlorides are less soluble in sea water than in pure water, since presence of chloride ions will force equilibrium to REACTANT (solid) side When a salt contains ions that can act as an acid or base, solubility will be affected by pH Ex: iron (III) hydroxide will be less soluble in basic solution, since Le Chatelier's principle predicts that equilibrium will be shifted to REACTANT (solid) side

when diluting strong acids/bases, always

add concentrated acid/base to a large volume of water helps dissipate energy that can be generated by exothermic solvaion process --> makes for safer dilution

weighing precautions

allow cooling before weighing recently heated items, bc convection currents may disturb balance and hot items may damage a delicate electronic balance use weighing boats to avoid damaging pan of balance with potentially corrosive metals

separatory funnel

allows for separation of immiscible liquids

funnel

along with filter paper can be used to separate solids from liquids

in insulators and semiconductors, valence and conduction bands are separated by _____

an energy gap in insulators, this gap is LARGE and CANNOT be bridged--> cannot conduct electricity in a semiconductor such as silicon, energy gap is smaller, and , with heating electrons can gain sufficient energy to cross from valence band to conduction band--> at elevated temperatures, Si's electrical conductivity is increased

calorimetry

an experimental technique used to measure change in energy of a chemical reaction or phase change

nonstandard conditions (voltaic cells)

apply Le Chatelier's principle to see if reaction will shift forward or backward to achieve standard conditions reactions that shift forward have higher voltages than standard reactions that shift backwards have lower voltages than standard

reactions that are nonspontaneous can be forced to proceed by

applying an external source of energy, such as electricity in electrolysis + battery charging, or use of light and other electronmagnetic radiation in photosynthesis and ionization processes

when molecules that have permanent dipoles approach one another, they will

arrange themselves so that the negative and positive ends of molecules attract one another

speed of gases (from maxwell boltzman)

at any given temperature, gas molecules have both high and low speeds as temperature increases, distribution of speeds is found to be across a wider range as temperature increases, a greater # of molecules are traveling faster

substitutional alloys

atoms of a comparable size to pure metal, substitute themselves for those pure metal atoms Ex: brass is made from copper and zinc..alloy will have a density that is somewhere between densities of 2 pure component metals and, like interstitial alloys, tend to be less malleable than pure metals

kelvin temperature is proportional to

average kinetic energy

***EXCEPTIONs**** 4s orbital has a slightly lower energy than the 3d orbital and, as a result, the 4s orbital is filled ____ the 3d orbital Similarly, 5s orbital has slightly lower energy than 4d orbitals and, as a result,5s orbital is filled before 4d orbital

before

elementary reactions involving two reactants =

bimolecular

diamond is made upon a 3D, tetrahedral unit where all of carbon atoms sp^3 hybridized and are

bonded to 4 other carbon atoms with very strong covalent bonds in a huge macrostructure large # of covalent bonds make diamond very strong + hard, and gives it a high melting and boiling point

the order with respect to a reactant is the exponent of the ___ term in the rate law

concentration

erlenmeyer flask

conical piece of lab equipment used for holding liquids NOT used for measuring

when a base is added to buffer, ___ reacts with it

conjugate acid

when weak base is neutralized by a strong acid, salt produced will be ___ of weak base

conjugate acid

when an acid is added to buffer, ___ reacts with it

conjugate base

when weak acid is neutralized by a strong base, salt produced will be ___ of weak acid

conjugate base

temperature of solid increases at ____ until it begins to melt

constant rate

double and triple bonds are stronger than single bonds BECAUSE

contain greater # of electrons --> stronger coulombic attractions

graphite has a 2D, sheet structure, where each carbon atom is sp^2 hybridized and

covalently bonded to three other carbon atoms in a plane strong covalent bonds give graphite a high melting point sheets stack in a layered structure --> specific properties -conduct electricity only in one plane -since one valence electron is "free" (3 are bonded) in each unit, electrons are spread out over each layer (delocalized) ...sea of electrons...conduct electricity along layers...but bc electrons cannot move b/w layers, no conduction from one layer to another -soft and can be used as lubricant..weak london dispersion forces hold layers together....can slide over one another...good lubricant

n-type (negative) semiconductors

created by adding atoms of elements from group 15 that have extra valence electron compared to Si

p-type (positive) semiconductors

created by introducing atoms of elements from group 13 with one less valence electron than Si

hydrogen bonds can occur between ___ parts of a single molecule

different

particle diagrams WITH VECTORS can be used to illustrate differing kinetic energies at

differing temperatures tails longer when particles moving faster (higher temp/KE)

uneven distribution of partial charges creates

dipole moment

shorter bonds, with atoms closer to one another, tend to be stronger than longer bonds with atoms further apart BECAUSE

distance b/w charges is smaller

bond length

distance b/w nuclei of atoms

hot plate

electric device that allows for controlled delivery of heat often contains a metallic stirrer to allow for mixing

PES diagram

electrons that are ejected analyzed using PES spectrum shows peaks that correspond to energy (x-axis) and relative number of electrons in any given sub-level (INTENSITIES; y-axis) electrons that are close to nucleus (greater attraction for nucleus bc Coulomb's law), will require larger energies to eject leads to evidence for shell model electrons in different shells are often widely separated in terms of energy Ex: even though 3s and 3p electrons in distinct orbitals that correspond to different energies, they are both in 3rd shell, and thus have similar energies...2s and 2p electrons are whole shell closer to nucleus, and as such are much more difficult to remove and require distinctly higher energies

aqueous solutions will also undergo electrolysis, but water is sometimes oxidized or reduced rather than

elements that make up solute

breaking bonds

energy absorbed endothermic

standard enthalpy of vaporization

energy change when 1 mol of substance converted from liquid to gas where liquid boiling, aomunt of energy that is added can be calculated using: q= (ΔHvap) n (n--> # mole)

standard enthalpy of fusion

energy change when 1 mol of substance converted from solid to liquid where solid melting, aomunt of energy that is added can be calculated using: q= (ΔHfus) n (n--> # mole)

standard enthalpies of formation

energy change when 1 mole of a substance is formed from its elements in their standard states

forming bonds

energy released exothermic

bond energy

energy required to dissociate (break) bond usually reported as kJ/mol

second law of thermodynamics

entropy or disorder of universe will increase over time

titration

experimental technique for collecting quantitative data about neutralization (and other) reactions as a bse is added to an acid, acid remains in excess and pH doesn't change much until equivalence point is reached

to determine order, must obtain

experimental values with changing concentration of each reactant measured

lowest energy orbitals are filled

first

metals and alloys may have some surface properties that are different from pure metal(s), due to _____

formation of an inert oxide layer, via a reaction with oxygen in the air Ex: in stainless steel, a chromium oxide layer is formed on surface of steel that helps prevent corosion

hybrid orbitals

formed by blending of s and p orbital linear - 2 - sp trigonal planar - 3 - sp^2 tetrahedral -4 - sp^3 (#s correspond to # of negative centers around central atom)

dynamic equilibrium is reached when

forward and reverse reactions continue at same rate, and concentrations of reactants and products are constant

spectator ions

found in exactly same form on both sides of equation (do not change) REMOVED when writing NET IONIC EQUATION

ionic equation

full equation splitting any aqueous substances into their ions, but leaving any non-aqueous substance intac

intermediates

generated and then used up (cancel)

Beaker

glass used to hold and heat solutions NOT used for measuring

a strong acid and a strong base have aneutralization reaction that ____

goes to completion K = 1 x 10^14 H3O+ + OH- --> 2H2O

free-moving valence electrons cause metals to be

good conductors of electricity

close-packed nature of structure makes metals ____ since energy can easily be passed from one positive kernel to the next

good conductors of heat

entropies are ___ for more complex molecules, greater when # individual particles of same phase increase, greater with increased temp(KE), and when single gas occupies a larger voluem

greater

ionic solids made up of ions with higher charges (larger q values) will have ___ attractions (larger Coulombic forces) and ____ melting points

greater higher

smaller ions can get closer together, so they will have smaller values for r and, consequently ___ attractions (larger Coulombic forces) and ___ melting points

greater higher

lower activation energy means

greater # of particles will possess required minimum energy + a greater # of collisions will be successful (will lead to a reaction)

larger Ksp values suggest

greater dissociation into ions and greater solubility

noble gases (group 18)

have a full outer s and p sub-shells of 8 electrons and, therefore, are stable and tend not to form ions

specific heat capacity

heat (energy) required to raise temperature of 1 g of substance by 1 degree celsius metals have low--> less energy required to raise temperatures

crucible

heat resistant container used to heat compounds can be used in combination with ring stand and clamp

ΔT increases in object, ΔT +, q + ...what is direction of heat transfer?

heat transferred into object endothermic

ΔT decreases in object, ΔT -, q - ...what is direction of heat transfer?

heat transferred out of object exothermic

What to know about ROOT MEAN SQUARE (rms) SPEED! (+ maxwell boltzman)

heavier particles move more slowly + particles at higher temperatures move more quickly at any given temperature, heavier gas molecules have lower speeds

____ or ___ can be used to eject electrons from atoms; this is called photoelectric effect

high energy X-rays or UV photons

clamp and ring stand

holds funnels, flasks, wire gauze for burning

precision

how close a series of measurements are to one another

accuracy

how close measurement is to accepted (actual) value

E=

hv (h = Planck's constant; v = frequency)

hydrogen bonding

hydrogen = exceptional when it forms a covalent bond --> its electron is held to one side of nucleus, leaving other side COMPLETELY EXPOSED any approaching negatively charged group can get very close to H nucleus --> unexpectedly large Coulombic attraction exaggerated when H bonded to a more electronegative element that is small enough to allow significant mintermolecular interaction (F, O, N) --> H bond 2 important consequences: anomalously high boiling point, increased viscosity can occur b/w different parts of single molecule

each gas in a mixture behaves independently from one another + pressure exerted by each can be calculated using

ideal gas equation for EACH GAS

thermodynamically favored rxns may still not occur in any measurable rate if they are slow, ie...

if they have a HIGH ACTIVATION ENERGY when this happens, rxn = kinetic control

surface tension

in body of a liquid, particles experience forces in 3 dimensions around them --> no net forces on particles -->pulled with net force INTO body of liquid caused by cohesion b/w particles --> contract to smallest possible size (sphere) + creates internal pressure at surface that can resist external pressure

polarizable

increased ability of large molecules to form extensive LDFs

entropy ___ with dispersal of particles

increases

dispersion forces increase with

increasing number of electrons/increasing surface area --> greater attraction --> higher melting/boiling points

some molecules have polar bonds but no dipole moments BECAUSE..

individual dipoles cancel out via symmetry Ex: CO2; CCl4

concentration cells

made from 2 half-cells with same metal/ion combinations, but with differing ion concentrations electrons flow from lower concentration half-cell to higher concentration half-cell in order to achieve equilibrium

when Q = Ksp, equilibrium has been established and all____ are constant

ion concentrations

Kw

ionic product of water although pure water is essentially covalent, there is a small amount of self-ionization that occurs b/w water molecules

coulomb's law and the size of the attractive force that it predicts, determines

ionization energy of any given electron

salt bridge allows

ions to flow, completing circuit in galvanic cell

elements + ions can be ___ with one another, meaning that they have the same electronic configurations

isolectronic

capacity of a buffer

its ability to continue to absorb any acid or base added dependent upon concentrations of 2 components of buffer; higher the concentrations, higher the capacity

rules for labeling blocks to remember sequencing of orbital fillings

label rows in table with period numbers and blocks with letters s, p, d, and f **Remember** -subtract 1 from period # when entering d block -subtract 2 from period # when entering f block -re-establish period # when entering p block

***the larger the individual ion concentrations at equilibrium, the ___ the Ksp value and the ___ soluble the salt

larger more

ionic substances are brittle because

like charges repel one another when the layers slide over one another

capillary action

liquid in very thin tube --> combination of cohesive forces + adhesive forces --> can add up to overcome force of gravity --> drawn up tube

transition metals (d-block elements)

lose electrons to have multiple positive charges based on what provides for most stable electronic configurations lose s electrons before d electrons when forming ions

stronger IMFs --> higher boiling points --> ___ vapor pressures

low

as a result of strong coulombic forces of ionic solids, tend to have ____, ____, and _____

low vapor pressures, high melting points, and high boiling points

breaking or forming a particular bond involves same

magnitude of energy change

dipole-diple

molecules w/ polar bonds (bc differences in electronegativity) and dipoles that do not cancel via symmetry will have permanent dipoles arrange themselves so that negative + positive ends attract one another to MAXIMIZE attraction and MINIMIZE repulsion

equivalence point

moles acid and base have been added in stoichiometric ratio neutralization is complete rapid change in pH

ionic substances can only conduct electricity when ___ or in solution because when they are in the solid state, ions are rigidly held, can gently vibrate, but cannot move in relation to one another

molten ions then free to move around one another so conduction of electricity is possible

Pauli exclusion principle

must be able to distinguish between all electrons in any atom; any 2 electrons that are found in the same orbital, in the same sub-shell, and in same shell, are given different "spins"

Effect of volume or pressure change (will NOT affect value of K)

must count # mols gas reactants and products to accurately predict if volume increases/pressure decreases, shifts to side w/ greatest # mols gas in order to INCREASE PRESSURE if volume decreases/pressure increases, shifts to side w/ least # mols gas in order to DECREASE PRESSURE

charged particles present in ionic solid explain how/why dissolve in water....when an ionic solid dissolves, ___ water molecules penetrate lattice and attach themselves to ions

polar process = hydration and ions said to be hydrated (nonpolar solvents will have no such attractions for ions, and strong forces b/w ions NOT interrupted)

mortar and pestle

porcelain piece of equipment that can be used for crushing and grinding

Heisenberg uncertainty principle

position and momentum of an electron can never be simultaneously, exactly known

structural factors like _____ and ___ can influence ability of an acid to lose H+ and therefore influence relative strength of a weak acid

presence of electronegative atoms bond strength

distillation (separation technique)

process of heating a liquid mixture and relying upon difference in boiling points of components to collect one (lower boiling point component) above other relies upon fact that IMFs b/w certain molecules are weaker than those b/w water

method of separation: distillation

process of heating a mixture of liquids and relying upon difference in boiling point to collect one (lower boiling-point component) above the other such as distillation of ethanol and water

method of separation: paper chromatography

process of separating components based upon their relative affinities for a stationary phase (paper) and moving phase (solvent) Rf values are calculated using: Rf = distance traveled by component of mixture/distance traveled by solvent front

chromatography (separation technique)

process of separation of components based upon their relative affinities (intermolecular attraction) for a stationary phase (often paper) and a moving phase (a solvent) components with a greater affinity for solvent travel further on chromatogram Rf values (retention factors) are calculated by applying following formula: Rf = distance traveled by component of mixture/distance traveled by solvent front the further a component travels on chromatogram, the greater its affinity for mobile phase + smaller its affinity for stationary phase --> these relative attractions depend upon intermolecular attractions

method of separation: filtration

process of using a filter paper to separate an insoluble solid from a solution or liquid, such as filtering a precipitate from a solution

galvanic cells use thermodynamically-favored REDOX reactions to

produce electrical energy via a flow of electrons

Bunsen Burner

produces a flame for heating

If energy is "taken away" from the system, result would favor formation of ___ or the ____ reaction

products exothermic

well plate

provides small reaction wells that allow reactions to be carried out on a microscale

in regions where temperature of solid, liquid, or gas is being increases, amount of energy added can be calculated using

q = m C ΔT

Coulomb's law

q1 and q2 are charges; r is distance between those charges

electron affinity

quantitative measurement of energy changes when adding electrons to atoms or ions (kJ/mol) (positive or negative depending on species formed) left to right across a period--> electron affinity increasingly positive within a group, more difficult to predict, but generally decreases as go from top to bottom

second order

rate of rxn is DIRECTLY PROPORTION to the SQUARE of concentration of one of reactants units for law = M s^-1 units for k = M^-1 s^-1

first order

rate of rxn is DIRECTLY PROPORTIONAL to concentration of one of reactants units for law = M s^-1 units for k = s^-1 radioactive decay is commonly this...constant half-life, meaning time taken for half of atoms to decay is constant and indepedent of initial concentration (k = .693/half-life)

zero order

rate of rxn is INDEPENDENT of concentration of reactant(s) units for law = s^-1 units for k = M/s

slowest elementary step is

rate-determining step (RDS)

limiting reagent/reactant

reactant that will be completely used up during chemical reaction and that determines all other amounts

excess reagent/reactant

reactant that will not be completely used up during chemical reaction and is left over at end of reaction

If energy is "added" to the system, result would favor the formation of_____ or the -___ reaction

reactants endothermic (think of energy as reactant in original if equation is originally endothermic, and as a product in original if equation is originally exothermic)

precipitation reactions (double displacement)

reactants are generally water-soluble ionic compounds that will dissociate into anions and cations **ALL sodium, potassium, ammonium, and nitrate salts are SOLUBLE ("SNAP")**

intermediates that appear in rate laws are generally replaced by

reactants they depend upon

neutralization reaction

reaction b/w H+ from an acid and OH- from a base to produce H2O commonly, these reactions form a salt in addition to water

***LOOK OUT for question where addition of a species that is NOT part of reaction, but DOES affect reaction, are added...for ex:

reaction below, H+ ions are not part of equilibrium, but when added they will react with OH- ions, removing them, and according to Le Chatlier's principle has effect of shifting reaction to the PRODUCTS side Ba(OH)2 ⇌ Ba2+ + 2OH-

weak acids/bases

reactions do NOT go to completion (ionization considered to be very small ~5% or less, w/ reverse reaction that sets up an equilibrium) to produce only small #s of H3O+ and OH-, respectively

elementary reactions

reactions that proceed from reactants to products in a single step with a single transition state

positive standard electrode reduction potential values means that the species in question will be

reduced more readily than H+ ions (and vice versa)

overall rate equation and RDS must be in agreement in terms of both

species present in each and in terms of matching stoichiometry with orders

arrhenius equation

relates rate constant to temperature and activation energy of reaction k increases with increasing temperature k decreases with increasing activation energy

extent to which equilibrium lies on one side or other determines

relative solubility of salt

when fusion (melting) begins, temperature ____ until entire solid has been converted to a liquid

remains constant

Buffer solution

resists change in pH when small amounts of acid or base are added maintains relatively constant pH

titrations in labs

rinse pipets and burets with solution that they will contain during titration, not H2O (to avoid diluting solution) read buret scale at point where bottom of meniscus is observed record one uncertain figure, but no more..in burets that are graduated to a tenth of amL, final digit -->0 or 5

liquid solutions do not _____ and cannot be separated by filtration

scatter visible light

reaction mechanism

sequence of bond-breaking and bond-making steps that lead to an overall chemical reaction each individual step = elementary step

"picture" of cell

shows oxidized and reduced species salt bridge flow of electrons may or may not have oxidized half-cells on left and reduced half-cell on right--CHECK + DO NOT ASSUME!

silicon forms a similar 3D structure to diamond

silicon is a semiconductor doping of silicon by introducing other elements causes formation of n-type and p-type emiconductors

titration curve for a polyprotic acid (one w/ more than one H+ ion to donate)

similar to monoprotic, but with multiple equivalence points (one for each H+ ion that it can donate to base)

in second order reaction, in graph of time vs. 1/concentration, k =

slope

interstitial alloys

small atoms fill spaces (interstices) b/w bigger atoms, making allow more rigid + less malleable than pure metal Ex: carbon is added to iron to make alloy steel

the larger the Ka, the ___ the pKa

smaller

the stronger the weak acid, the larger the Ka, the ___ the pKA

smaller

all ____ salts are soluble in water

sodium potassium ammonium nitrate

Ksp

solubility product constant

general preparation of solutions procedure

some water is added to a volumetric flask of appropriate size using suitably sized pipet/buret, [solution] is slowly + carefully transferred to volumetric flask w/ gentle swirling to ensure good mixing when all of concentrated solution has been added to flask, solution is filled up to mark of volumetric flask with solvent

rate of reaction for an elementary step is based on

stoichiometric coefficients of reactants in elementary step THIS SHOULD NOT BE CONFUSED WITH USING STOICHIOMETRIC COEFFICIENTS OF OVERALL REACTION MADE UP FROM A SERIES OF ELEMENTARY STEPS TO DETERMINE ORDER (THIS METHOD IS INCORRECT)

covalent network solids

structures where non-metal atoms are bonded to one another with strong covalent bonds in a massive 2 or 3D, continuous network Ex: diamond, graphite, silicon dioxide, silicon carbide Group 14 elements are good candidates since can form 4 covalent bonds melting points are high and solids are hard + bc of strength of covalent bonds and fixed bond angles

coffee cup calorimeter

styrofoam cups commonly used as insulators to measure temperature changes without loss of energy to surroundings

energy released in forming product bonds is

sum of all average bond energies in products (exothermic)

energy required to break all reactant bonds is

sum of all average bond energies in reactants (endothermic)

energy change in reaction as a whole is

sum of breaking (endothermic process) and forming (exothermic process) can be negative or positive depending on relative magnitude of the two

individual steps of mechanism must

sum to give reaction stoichiometry of overall reaction

in an endothermic reaction, thermal energy is transferred FROM

surroundings

in an exothermic reaction, thermal energy is transferred TO

surroundings

for strong acids that completely dissociate bc [H3O+] will be same as [HA], simply ...

take -log[HA] to yield pH

electronegativity

the ability of an atom to attract electrons to itself within a covalent bond increases across a period rom left to right increases up a group from top to bottom fluorine is most electronegative element (noble gases usually omitted because they form so few covalent bonds)

bond length b/w atoms in a covalent bond is

the distance between centers of atoms, when potential energy of electrostatic (Coulombic) interaction is at a MINIMUM

first ionization energy

the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to produce 1 mole of gaseous ions (kJ/mol) (endothermic; +)

ionization energy

the energy required to remove the least tightly held electron in a given species proportional to the nuclear charge (# protons) and distance between nucleus and electron to be removed

dipole-induced dipole

the large the dipole of polar molecule + more polarizible non-polar molecule --> stronger the dipole-induced dipole attractions

mole fraction (X)

the number of moles of a particular substance divided by total number of moles --> Pa = XAP total

overall order is

the sum of individual orders

oxidation and reduction must take place together...

they do not occur in isolation from one another there has to be a "source" and a "sink" for electrons

when Q>Ksp, product of equilibrium ion concentrations is ____ and equilibrium must be established by reducing those concentrations and forming more solid

too large (i.e. PRECIPITATION occurs)

when Q<Ksp, product of equilibrium ion concentration is ___ and equilibrium must be established by increasing those concentrations and forming more ions

too small (i.e. no solid (precipitate) is formed)

Dalton's law

total pressure of a mixture of ideal gases is the sum of their partial pressures

heat

transferred kinetic energy

colloids

typically have particles that are larger in size than molecules in a soln, up to appx. 1000 nm --> if exceeds--> "suspension" particle size distinctions mean that a mixture can appear homogeneous or heterogeneous depending on scale on which observed

elementary reactions involving single reactant =

unimolecular

burette or buret

use for volumetric delivery of solutions used in titration experiment stopcock is small handle that controls delivery of liquid

volumetric pipet

used for accurate measurement and transfer of liquid volumes often used during titrations and when diluting solutions

graduated cylinder

used for measuring volumes of liquids MORE accurate than a beaker and LESS accurate than volumetric equipment, such as pipets and burets

Büchner Funnel

used for suction filtration along with a filtering flask

filtering flask

used in combination with vacuum suction and Büchner funnel

mass spectrometry

used to ID varying masses of isotopes in a naturally occurring sample of any given element. works as follows: 1) ionization --> positive ions are formed by a sample of vaporized atoms being bombarded with electrons --> knock valence electrons out of sample --> positive ions in sample (ALWAYS) 2) acceleration --> positive ions accelerated into a singular beam by use of an electric field 3) deflection --> positive ions deflected in a magnetic field according to their mass and charge --> lighter and more highly charged ions are deflected more than heavier and lower charged ions 4) detection --> beam of deflected positive ions are detected and converted to a readable output (mass spectrum)

volumetric flask

used to accurately prepare solutions of various concentrations often used in titrations

Beer-Lambert law

used to assess concentration of a solution (almost exclusively in colored solns on AP), by relating absorbance of solution to concentration of solution A = abc (A = absorbance, a = absorptivity coefficient --> constant for a particular solution, b = path length--> distance that light passes through solution, c= concentration colorimeter is used and wavelength of light chosen for experiment should be complementary to wavelength of light reflected by solution (complementary to color of solution) --> this allows for maximum absorbance (important in collecting reliable data over range of concentrations) linear plots of absorbance vs. concentration found) generally only useful for colored solutions

infared radiation

used to cause bending and stretching of covalent bonds different types of covalent bonds will interact with IR in different ways --> IR spectroscopy used to ID presence of different types of covalent bonds present in larger molecules (mainly used in organic chemistry)

ultraviolent radiation and visible light

used to cause electron transitions within atoms (promotion to higher energy levels and ionization energies) and to collect data about electronic structure of atom and electron shell model

evaporating dish

used to hold aqueous solutions as they are heated in order to evaporate water and leave the solid

thermometer

used to measure temperature

distillation apparatus

used to separate a mixture of compounds based on boiling point

electrical decomposition

using electricity to cause decomposition (electrolysis)

electrons reside in ___ band, but in order for conduction to take place, must be promoted to ___ band

valence conduction

silicon's conductivity increases with an increase in temperature..in electronic structure of solids, there are 2 "bands" of permitted energy levels for electrons: ___ and ___-

valence band conduction band

metallic bonding

valence electrons delocalized and mobile around regular arrangement of cations greater number of delocalized electrons, stronger metallic bond

when molecules that have different temperatures collide, KE is transferred from

warmer one to cooler one until temperature (average KEs) are same

molecular solids

when discrete molecules, made from nonmetals, are attracted to one another with only London dispersion forces (Ex: iodine) london forces mean that tend to have low melting points + be soft bc only a weak interaction b/w molecules no ions and no free-moving electrons are present (since electrons are tied up in covalent bonds), so expected to be non-conductors some important large molecules and polymers in biology are observed to be molecular solids

effect of concentration ___ affect K value

will NOT

when selecting which resonance most likely, chose structure with

zero formal charges +/or formal charges with absolute values as low as possible +/or keep any negative formal charges on most electronegative atoms

as absolute zero is approached (O K), particles approach

zero kinetic energy

q= mC _____

ΔT