28-30 Flashcards
reaction intermediates don’t pile up; when confronted by a slow step, they go in the reverse direction
Catalysts are not mentioned, either. Catalysts can be modified during a reaction, but return to original state at the end (CATALYST = REGENERATED)
three factors that influence rate
LOWER activation energy (via catalyst)
MORE CONCENTRATED reactants
HIGHER temperature
TEMPERATURE influences rate constant, k; does NOT change Ea (!IMPORTANT)
Catalyst == Ea
NOT G, H, or S
rate constant k
rate / [A]^a [B]^b
equillibrium
generation of product is the same as generation of reactants (rate = reverse_rate)
DYNAMIC equilibrium
K_a, K_b, K_s
all equilibrium constants
K_eq is a constant at a given temperature
TEMPERATURE INFLUENCES K_eq
K_a, K_b, K_s
all equilibrium constants
K_eq is a constant at a given temperature
TEMPERATURE INFLUENCES K_eq
K_sp is the solubility (salt) product constant
reaction quotient
Q - same as K_eq but fluctuates
Q > Keq, reverse reaction is favored
Q < Keq, forward reaction is favored
le Chatelier’s principle is related to Q
pressure and le Chatelier’s equation
see which side has more moles of gas
increased pressure = reduced volume = favors the fewer moles
PRESSURE CAUSES REACTIONS TO CONDENSE
reaction quotient
Q - same as K_eq but fluctuates
Q > Keq, reverse reaction is favored
Q < Keq, forward reaction is favored
le Chatelier’s principle is related to Q
Q = K_eq, reaction is at equilibrium ∆G = 0, reaction is at equilibrium
you can also calculate Q by [Partial pressure A]^a / [Partial pressure B]^b
temperature and le Chatelier’s equation
if the product is heat, then reducing temperature favors the forward process
likewise, adding heat shifts left
“LOWERING TEMPERATURE favors the exothermic reaction, raising temperature favors endothermic”
CHECK TO SEE ∆H and add heat to the equation
hydration
when solvent is water, it is hydration and aqueous
solvent is higher in proportion than solute
strong electrolyte = good conductor of electricity
covalent bonds = nonelectrolytes
ionizability factor (i)
tells us how many particles are dissociated in solution
glucose i =1
nacl i=2
phase solubility rules
- solubility of solids in liquids increases with temperature
- solubility of gases in liquids decrease with increasingly temperature
- gases dissolve better under high pressure
solubility of a gas
Solubility = kP
k, Henry’s law
P, partial pressure of gas above the liquid
K_sp
K_sp = [Mg2+][OH-]^2
leave Mg(OH)2 out because it is a solid
equilibrium = rate at which ions go into solution same as precipitation
Q_sp and Ksp
K_sp is when the solution is SATURATED
if Q_sp is greater than K_sp, then salt will precipitate
common ion effect
hydroxide is added, will shift another chemical balance
complex ion formation
creating a complex ion with Lewis base (NH3) takes away a ion from solution, driving forward the propensity of solid salt to exist as ions in solution
complex ion formation
creating a complex ion with Lewis base (NH3) takes away a ion from solution, driving forward the propensity of solid salt to exist as ions in solution
polyprotic acids and amphoteric substances
HCO3- is both a base and acid = amphoteric
the relationship between [H3O+] and [OH-]
K_w is always 10^-14 (autoionization)
K_w increases with increasing temperature
adding acid will shift the equation to the left, decreasing [OH-]
[OH-] = K_w/[H3O+]
pOH and pH always equal for acid-base conjugate pair
14 (based on K_w)
p
NEGATIVE LOG
“peeing under a (-) log”
acid-base conjugate pair
KaKb = 10^-14
pKa + pKb = 14
LEWIS acid and base
ACID - electron RECEIVER
BASE - electron donor
A lewis acid causes another molecule to give up an Hydrogen
H+ is a conjugate acid, because it ACCEPTS OH-
OH- donor = BASE
strength of acid
strong = completely dissociates, HIGH K_a value
HI, HBr, HCl
HClO4, H2SO4, HNO3
strength of base
K_b
Group 1 hydroxides
Group 1 oxides
Ba(OH)2, Sr(OH)2, Ca(OH)2, “CAlifornia has StRong BAses”
Metal amides (NaNH2)
conjugate acid has NO acidic properties
a 0.01 M solution of HCl is what pH
0.01 moles / L
pH = -log(0.01) = 2
K_a
[H+][CN-] / [HCN] = x^2 / (starting amount)
Neutralization
equimolar strong acid + strong base = neutral pH
weak acid + weak base = variable pH (not neutral)
weak acid or base + strong base/acid (equimolar) = complete neutralization
H+ + OH- -> H2O + heat
ALL equimolar neutralization reactions go to completion
