Studied by 2 peoplereversible reactions
reactions that can take place in both directions
equilibrium
when the concentrations of the reactants and products stop changing
the rate of the forward reaction = the rate of the reverse reaction
at equilibrium, what is equal?
Keq = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ
Keq Formula
(equilibrium concentrations)
equilibrium constant
favors the reactants
a small Keq indicates the reaction
favors the products
a large Keq indicates the reaction
take the reciprocal
if you reverse a reaction, you _______________ the Keq
raise the Keq to the x power
if you multiply a balanced chem equation by a coefficient of x, you __________________ the Keq
multiply
if you add two reactions together, you ________________ the Keq
Q = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ
Q Formula
(initial concentrations)
reaction quotient
favors the forward direction
if Q > Keq, the reaction
favors the reverse direction
if Q < Keq, the reaction
has no direction affinity
if Q = Keq, the reaction
le chartelier's principle
states that if a system at equilibrium is disturbed by a change in temperature, pressure, or a component concentration, the system will shift its equilibrium position so as to counteract the effect of the disturbance
the solubility product (Ksp)
the degree to which dissolution occurs
Ksp = [A⁺]ᵃ[B⁻]ᵇ
the solubility product
low solubility
a small Ksp value indicates
high solubility
a large Ksp value indicates
molar solubility
molarity of a solute in a saturated solution (S)
common ion
an ion that is common to two or more ionic compounds
common ion effect
If one of the ions in a solution equilibrium is already dissolved in the solution, the equilibrium will shift to the left and the solubility of the salt will decrease
exothermic reaction
ΔH < 0
endothermic reaction
ΔH > 0
left
if you raise the temperature of a exothermic reaction, the reaction will shift to the
right
if you lower the temperature of a exothermic reaction, the reaction will shift to the
right
if you raise the temperature of a endothermic reaction, the reaction will shift to the
left
if you lower the temperature of a endothermic reaction, the reaction will shift to the
Equilibrium constant expression - Aqueous
Kc = [products]/[reactants]
Equilibrium constant expression - Pressure Only (g)
Kp = [products]/[reactants]
False
True
True
1 atm =
760 torr, 760 mmHg
Solids and liquids are
not in the Equilibrium constant
Forward reaction means:
Reactants to Products
Reverse reaction means:
Products to Reactants
Kc or Kp equation
Kc (or Kp) = [products]/[reactants]
Qc or Qp equation
Qc (or Qp) = [products]/[reactants]
Kc (or Kp) meaning
K gives the value of the reaction at Equilibrium
Qc (or Qp) meaning
Q gives the value of the reaction at any given time
Q compared to K
Q is compared to K to determine if the forward or reverse reaction are favored based on it being greater than, less than or equal to K
Q = K
Reaction is at equilibrium, neither the forward nor reverse reaction is favored
Q > K
Forward reaction (reactants to products) is favored / shifts to the left
Q < K
Reverse reaction is favored (products to reactants) / shifts to the right
Small K means
Because K = [products]/[reactants]
reactant number is bigger, because reactants are on the bottom and thus make a small number
Reactants are favored.
Bigger K means
Because K = [products]/[reactants]
product number is bigger, because product are on the top and thus make a larger number
Products are favored
Kp and Kc Units
No Units!
Le Chatelier's Principle
If a stress is imposed on a system at equilibrium the position of the equilibrium will shift in a direction that reduces that stress
LCP - Adding a product
shifts left (toward reactants)
LCP - Adding a reactant
shifts right (toward products)
LCP - Removing product
shifts right (toward products)
LCP - Removing reactant
shifts left (toward reactants)
LCP - Increasing volume
Shifts toward the side with more moles. This is similar to a decrease in pressure.
LCP - Decrease volume
Shifts toward the side with fewer moles. This is similar to an increase in pressure.
LCP - In an endothermic reaction, increasing temperature means...
Endo heat comes indoors, and is thus a reactant
so adding reactant, shifts right, the value of K increases because the concentration of the products increase and the concentration of the reactants decrease.
LCP - In an endothermic reaction, decreasing temperature means...
Endo heat comes indoors, and is thus a reactant
so removing reactant, shifts left, value of K decreases because the concentration of the products decrease and the concentration of the reactants increase.
LCP - In an exothermic reaction, increasing temperature means...
Exo heat exits and is thus a product so adding product, shifts left, value of K decreases because concentration of the products decrease and the concentration of reactants increase.
LCP - In a exothermic reaction, decreasing temperature means...
Exo heat exits and is thus a product so removing product, shifts right, value of K increases because the concentration of the products increase and the concentration of the reactants decrease.
LCP - Adding a catalyst...
Does NOT change the concentration
LCP - Adding an inert gas
Does NOT change the concentration
ΔH + then
Endothermic heat is a reactant
ΔH - then
Exothermic heat is a product
What happens to Kc in the reverse reaction?
The products become the reactants going backwards and the reactants are now products....
Kc = [reactants]/[products]
Kc equation
Catalyst as it relates to Equilibrium
has no effect on the position of equilibrium but lowers activation energy, increasing the rate of forward and reverse reactions(gets to equilibrium faster)
What happens to the value of K when flipping reactants and products?
becomes 1/K
K of reverse reaction
1/K original
Doubling K to equal an equation
original K squared
Halving K to equal an equation
original K to 1/2 power (sqrt of K)
Ksp
solubility product constant
Ksp=[A+]^m[B-]^n
Ksp equation
molar solubility
the solubility of a compound in units of moles per liter
Q<Ksp
precipitate forms
Q>Ksp
no precipitate forms
Two Factors Affect Solubility
pH and Common Ion Effect
Heterogeneous Equilibrium
equilibrium involving reactants and/or products in more than one phase
Homogeneous Equilibrium
a state of equilibrium that occurs when all the reactants and products of a reaction are in the same physical state
Phases used in Kc
aq and gas
Phases used in Kp
gas
Note
Flashcard