Should be on the Test

Question 1

when not at equilibrium

Answer 1

Q = [Prod]/[Reac]

(can use Q for ANY concentrations)
[tells us which direction a rxn will shift to achieve equilibrium]
Q < means move right
Q > means move left

Question 2

where does reduction occur?

Answer 2

cathode

Question 3

predicting change in entropy

Answer 3

4. molecular complexity (Ar < CO < CO2)
5. chemical rxns (A -> 2B = +S [more moles of products])

Question 4

state function

Answer 4

entropy is a state function (doesn’t care about the path; only the initial and final state)

Question 5

entropy with constant T

Answer 5

∆S = q(rev)/T

Question 6

third law of thermodynamics

Answer 6

entropy of a perfectly organized crystal at absolute zero is zero [no disorder]

Question 7

value of Q at STP

Answer 7

Q = 1

Question 8

what value of K means for spontaneity

Answer 8

K < 1 (lnK is —; ∆G° is +) [spontaneous in reverse]
K > 1 (lnK is +; ∆G° is —) [spontaneous in forward]
K = 1 (lnK is 0; ∆G° is 0) [doesn’t favor either direction]

Question 9

IMF and vapor pressure

Answer 9

IMF determine vapor pressure [stronger IMF = lower vapor pressure]

Question 10

why do stronger IMF mean lower vapor pressure

Answer 10

more heat must be introduced to break forces of the liquid to go to gas phase

Question 11

raoult’s law

Answer 11

Pa = XaPa*

Pa* = vp of pure solvent

Question 12

attracted to water

Answer 12

hydrophilic

Question 13

repelled by water

Answer 13

hydrophobic

Question 14

molality

Answer 14

n/kg [m]

Question 15

solubility of a gas (henry’s law)

Answer 15

s = k(H)P

gases become less soluble at high temps.

Question 16

IΔE box method

Answer 16

used for:

equilibrium

finding pH

solubility product/precipitation rxns

Question 17

polyprotic acid

Answer 17

H2SO3 + H2O ⇄ H3O+ HSO3- [K1]
HSO3- + H2O ⇄ OH- SO3 (2-) [K]

K(1)&raquo_space; K(2) ALWAYS because it takes much more energy to remove H+ from a negative molecule vs a neutral molecule
(can ignore the weaker acid when calculating pH)

Question 18

amphoteric acids

Answer 18

species that is both an acid or a base

HSO3- + H2O ⇄ H3O+ SO3-
HSO3- + H2O ⇄ OH- H2SO3

Question 19

salts + properties

Answer 19

can be acidic or basic

NaF + H2O ⇄ Na+ + F- + H2O
F- + H2O ⇄ OH- + HF

NaF is a base, and conjugate is HF

Question 20

acid strength (family trends)

Answer 20

HF (weak
HCl (stronger)
HBr (stronger)
HI (strongest) [more shielding]

Question 21

acid strength (oxyacid groups)

Answer 21

HClO < HClO2 < HClO3 < HClO4

the oxygen atoms pull e-density away from the OH group. more oxygens = more easy the H+ comes off

Question 22

common-ion effect

Answer 22

the presence of both acid and conjugate base means the base does NOT neutralize the base. because it is at equilibrium, if one side changes, the rxn will shift the rxn back

Question 23

solubility product

Answer 23

AgCl ⇄ Ag+ + Cl-

Ksp = [Ag+][Cl-]

if small: not very soluble

Question 24

precipitation reactions

Answer 24

precipitation reactions

Question 25

[Ag+][Cl-] < Ksp

Answer 25

(Q < K) rxn shifts right (no precipitate)

Question 26

[Ag+][Cl-] = Ksp

Answer 26

(Q = K) solution is saturated

Question 27

[Ag+][Cl-] > Ksp

Answer 27

(Q > K) rxn shifts left (precipitate forms)

Question 28

where does oxidation occur?

Answer 28

anode

Question 29

volt

Answer 29

Joule / coulomb (J/c)

Question 30

coulomb

Answer 30

measure of charge

e- = 1.6x10^-18 c

Question 31

e°cell values

Answer 31

+ means spontaneous (galvanic)

— means nonspontaneous (electrolytic)

Question 32

what happens when you change conc. (rate law)

Answer 32

r = k[A]^2 [B]^1

if A doubles: [2]^2 = x4

if A triples: [3]^2 = x9

if B halves: [2]^1 = x1

if B thirds: [3]^1 = x1

Question 33

arrhenius equation in y=mx+b

Answer 33

lnk = (-Ea/R)*(1/T)+lnA

y = m x + b