Equilibrium and Kinetics Review
Name: ________________________________ Period: ________
Part 1: LeChatelier’s Principle Determine which direction the listed stress will shift the equilibrium. State how the shift will change
the amounts of each material present to reach a new equilibrium.
2N2(g) + O2(g)  2N2O(g) + heat
Reaction #1:
Stress
Equilibrium Shift
(right, left, none)
N2
inc/dec/no change
O2
inc/dec/no change
N2O
inc/dec/no change
Decrease Pressure
Increase N2 concentration
Increase Heat
Decrease N2O concentration
Reaction #2:
2Al(s) + 6HCl(aq) + heat  2AlCl3(aq) + 3H2(g)
Stress
Equilibrium
Shift (R,L, none)
Al
inc/dec/no change
HCl
inc/dec/no change
AlCl3
inc/dec/no change
H2
inc/dec/no change
Decrease heat
Increase AlCl3 concentration
Decrease H2 concentration
Add Al
Part 2: Equilibrium Expressions and Equilibrium Constants
Reaction #1: 4 HCl(g) + O2(g)  2H2O(g) + 2 Cl2(g) at equilibrium: [HCl] =1.2x10-3M, [O2] = 3.8x10-4M, [H2O]=
0.058M, [Cl2]=0.058M
Write the equilibrium expression
Calculate the value for the equilibrium constant
Reactant or
Product Favored?
Reaction #2: K2O(s) + H2O(l)  2KOH(aq) at equilibrium: [KOH] = 0.05M
Write the equilibrium expression
Calculate the value for the equilibrium constant
Reaction #3: N2(g) + O2(g)  2 NO(g)
Write the equilibrium expression
Reactant or
Product Favored?
at 25°C the K= 6.9 x 10-4 At equilibrium [O2] = 0.0078M, [N2] = 0.041M
Calculate the value of [NO]
Reactant or
Product Favored?
Reaction #4: N2(g) + 3H2(g)  2 NH3(g)
Write the equilibrium expression
at 25°C the K=5.2x10-5 At equilibrium [H2] = 0.80M, [NH3] = 0.0073M
Calculate the value of [N2]
Reactant or
Product Favored?
Kinetics
1. Draw a potential energy diagram for each of the following:
Exothermic Reaction
Endothermic Reaction
a. Label the diagrams with the following: reactants, products, activation energy, activated complex, H.
b. On each of the previous diagrams draw a dashed line to show how the reaction would change with the
addition of a catalyst.
2. Compare the chemical potential energy of products to that of the reactants for an exothermic reaction.
3. Compare the chemical potential energy of products to that of the reactants for an endothermic reaction.
4. Explain how each factor affects reaction rate (Be sure to mention if the rate increases or decreases). Be sure to explain
why this occurs in terms of the Collision Theory:
a. Temperature
b. Surface Area
c. Concentration
d. Catalyst
5. Give two reasons why many collisions between particles do not lead to a chemical reaction.
KEY
Part 1: LeChatelier’s Principle Determine which direction the listed stress will shift the equilibrium. State how the shift will change
the amounts of each material present to reach a new equilibrium.
2N2(g) + O2(g)  2N2O(g) + heat
Reaction #1:
Stress
Decrease Pressure
Equilibrium Shift
(right, left, none)
Left
N2
inc/dec/no change
Inc
O2
inc/dec/no change
Inc
N2O
inc/dec/no change
Dec
Increase N2 concentration
Right
Dec
Dec
Inc
Increase Heat
Right
Inc
Inc
Dec
Decrease N2O concentration
Right
Dec
Dec
Inc
Reaction #2:
2Al(s) + 6HCl(aq) + heat  2AlCl3(aq) + 3H2(g)
Stress
Decrease heat
Equilibrium
Shift (R,L, none)
Left
Al
inc/dec/no change
No change
HCl
inc/dec/no change
Inc
AlCl3
inc/dec/no change
Dec
H2
inc/dec/no change
Dec
Increase AlCl3 concentration
Left
No change
Inc
Dec
Dec
Decrease H2 concentration
Right
No change
Dec
Inc
Inc
Add Al
None
No change
No change
No change
No change
Part 2: Equilibrium Expressions and Equilibrium Constants
Reaction #1: 4 HCl(g) + O2(g)  2H2O(g) + 2 Cl2(g) at equilibrium: [HCl] =1.2x10-3M, [O2] = 3.8x10-4M, [H2O]=
0.058M, [Cl2]=0.058M
Write the equilibrium expression
Calculate the value for the equilibrium constant
Reactant or
Product Favored?
K = [H2O]2[Cl2]2 / [HCl]4[O2]
1.4 x 1010
Reaction #2: K2O(s) + H2O(l)  2KOH(aq) at equilibrium: [KOH] = 0.05M
Write the equilibrium expression
Calculate the value for the equilibrium constant
K = [KOH]2
Reaction #3: N2(g) + O2(g)  2 NO(g)
Write the equilibrium expression
K = [NO]2 / [N2] [O2]
0.0025
Product
Reactant or
Product Favored?
Reactant
at 25°C the K= 6.9 x 10-4 At equilibrium [O2] = 0.0078M, [N2] = 0.041M
Calculate the value of [NO]
Reactant or
Product Favored?
4.7 x 10-4 M
reactant
Reaction #4: N2(g) + 3H2(g)  2 NH3(g)
Write the equilibrium expression
K = [NH3]2 / [N2] [H2]3
at 25°C the K=5.2x10-5 At equilibrium [H2] = 0.80M, [NH3] = 0.0073M
Calculate the value of [N2]
Reactant or
Product Favored?
2.0 M
Reactant
Kinetics
1. Draw a potential energy diagram for each of the following:
Exothermic Reaction
Endothermic Reaction
a. Label the diagrams with the following: reactants, products, activation energy, activated complex, H.
b. On each of the previous diagrams draw a dashed line to show how the reaction would change with the
addition of a catalyst. (there should be a curved, dashed line under the activation energy showing a smaller
activation energy.)
2. Compare the chemical potential energy of products to that of the reactants for an exothermic reaction.
products are lower than the reactants
3. Compare the chemical potential energy of products to that of the reactants for an endothermic reaction.
reactants are higher than the products
6. Explain how each factor affects reaction rate (Be sure to mention if the rate increases or decreases). Be sure to explain
why this occurs in terms of the Collision Theory:
a. Temperature: higher temps increase rxn rate because at higher temps, molecules have higher kinetic energy
leading to more collisions with more energy.
b. Surface Area: A larger surface area (smaller particle size) leads to higher rxn rate because more collisions can
occur between the reactants with more surface area exposed
c. Concentration: A higher concentration of reactants will lead to more collisions between the reactant particles
leading to a faster reaction.
d. Catalyst: A catalyst creates an alternate pathway for a reaction to occur which lowers the activation energy and
speeds the reaction up.
7. Give two reasons why many collisions between particles do not lead to a chemical reaction.
1. not enough energy, or 2. wrong orientation of particles