1. Consider the following equilibrium: H2O(g) + CO(g) ⇄ H2(g) + CO2(g)
A closed container is initially filled with H2O and CO. As the reaction proceeds towards equilibrium the
A. [CO] and [CO2] both increase
B. [ CO] and [CO2] both decrease
C. [CO] increases and [CO2] decreases
D. [CO] decreases and [CO2] increases
2. Consider the following equilibrium: 2SO3(g) ⇄ 2SO2(g) + O2(g)
At equilibrium, the rate of decomposition of SO3
A. Equals the rate of formation of O2
B. Equals the rate of formation of SO3
C. Is less than the rate of formation of O2
D. Is less than the rate of formation of SO3
3. Which of the following is true for all equilibrium systems?
A. The mass of reactants is equal to the mass of products
B. Addition of a catalyst changes the equilibrium concentrations
C. The concentration of reactants is equal to the concentration of products
D. The rate of the forward reaction is equal to the rate of the reverse reaction
4. Consider the following
I Constant Temperature
II Equal concentrations of reactants and products
III Equal rates of forward and reverse reactions
A system at equilibrium must have
A. I and II only
B. I and III only
C. II and III only
D. I, II , and III
5. Consider the following: N2O4(g) ⇌ 2NO2(g)
Colourless Brown
NO2 is placed in a flask at a constant temperature. Which of the following is true as the system approaches equilibrium?
A. The colour gets darker as [NO2] increases.
B. The colour gets lighter as [NO2] decreases.
C. The colour gets darker as [N2O4] increases.
D. The colour gets lighter as [N2O4] decreases.
6. Which of the factors below is not a condition necessary for equilibrium?
A. a closed system
B. a constant temperature
C. equal forward and reverse reaction rates
D. equal concentrations of reactants and products
7. Consider the following reaction: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -197 kJ/mol
Which of the following will not shift the equilibrium to the right?
A. Adding more O2
B. Adding a catalyst
C. Increasing the pressure
D. Lowing the temperature
8. Consider the following equilibrium system: CO2(g) + H2(g) ⇄ CO(g) + H2O(g)
Which of the following, when added to the system above, would result in a net decrease in [H2O]?
A. CO2
B. H2
C. CO
D. H2
9. Consider the following equilibrium: 2NO(g) + Cl2(g) ⇄ 2NOCl(g)
At constant temperature and volume, Cl2 is added to the above equilibrium system.
As equilibrium re-establishes, the
A. [NOCl] will decrease
B. The temperature increases
C. [NO] will increase
D. [NOCl] will increase
10. A 1.00 L flask contains a gaseous equilibrium system. The addition of reactants to this flask results in a
A. Shift to the left and decrease in the concentration of products
B. Shift to the left and increase in the concentration of products
C. Shift to the right and decrease in the concentration of products
D. Shift to the right and increase in the concentration of products
11. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -198 kJ
There will be no shift in the equilibrium when
A. More O2 is added
B. Catalyst is added
C. The volume is increased
D. The temperature is increased
12. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO 3(g)
Which of the following will shift the equilibrium to the right?
I. Adding more O2
II. Adding more SO3
III. Adding a catalyst
A. I only
B. III only
C. I and II only
D. II and III only
13. Consider the following equilibrium:
CO(g) + 2H2(g) ⇌ CH3OH(g) + energy
Which of the factors below would decrease the concentration of CH3OH at equilibrium?
A. an addition of CO
B. an increase in H2
C. a decrease in the temperature
D. an increase in the temperature
14. Consider the following equilibrium: N2O4(g) + energy ⇌ 2NO2(g)
How are N2O4 and NO2 affected by the addition of He into the container at constant volume.
N2O4 NO2
A. no change no change
B. no change increases
C. increases decreases
D. decreases increases
15. The Haber Process is used to produce ammonia commercially according to the following equilibrium:
N2(g) + 3H2(g) ⇌ 2NH3(g) + energy
Which of the following conditions will produce the highest yield of ammonia?
A. increase temperature and increase pressure
B. increase temperature and decrease pressure
C. decrease temperature and increase pressure
D. decrease temperature and decrease pressure
16. Consider the following equilibrium: 2O2(g) + N2(g) ⇄ N2O4(g)
When 2.0 mol of O2 and 3.0 mol of N2 were placed in a 10.0 L container at 25oC, the value of Kc = 0.90.
If the same number of moles of reactant were placed in a 5.0 L container at 25oC, the equilibrium constant would be
A. 0.011
B. 0.45
C. 0.90
D. 1.80
17. Consider the following: 2H2O(g) ⇄ 2H2(g) + O2(g)
When 0.1010 mol H2O is placed in a 1.000 L container, equilibrium is established.
The equilibrium concentration of O2 is 0.0010 mol/L. the equilibrium concentrations of H2O and H2 are
[H2O] [H2]
A 0.0990 0.0020
B 0.1000 0.0010
C 0.1005 0.0005
D 0.1010 0.0020
18. Which of the following equilibrium systems most favors the products?
A. Cl2(g) ⇄ 2Cl(g) Kc =6.4 x 10-39
B. Cl2(g) + 2NO(g) ⇄ 2NOCl(g) Kc =3.7 x 108
C. Cl2(g) + 2NO2(g) ⇄ 2NO2Cl(g) Kc =1.8
D. 2HCl(g) ⇄ H2(g) + Cl2(g) Kc =2.0 x 10-3
19. Consider the following equilibrium and experimental data:
N2O4(g) ⇄ 2NO2(g)
Initial Equilibrium
[N2O4] [NO2] [N2O4] [NO2]
Trial 1 0.0400 M 0.0000 M 0.0337 M 0.0125 M
Trial 2 0.0200 M 0.0600 M 0.0429 M 0.0141 M
Which of the following represents the Kc value?
A. 0.00464
B. 0.371
C. 0.742
D. 216
20. Which Kc is most likely to favor the formation of reactants?
A. Kc = 1.65 x 104
B. Kc = 5.69 x 10-11
C. Kc = 3.95 x 10-11
D. Kc = 7.67 x 104
21. Consider the following equilibrium: 2COF2(g) ⇌ CO2(g) + CF4(g)
Initially, 0.32 M CO2 and 0.40 M CF4 are placed in a container. At equilibrium, it is found that the [COF2] is 0.16 M.
What is the value of Kc?
A. 0.026
B. 1.5
C. 9.3
D. 3.0
22. At a certain temperature, the equilibrium constant is 3.86 for the reaction
H2(g) + CO2(g) H2O(g) + CO(g)
If 0.560 mol H2(g) and the same amount of CO2(g) is placed in a 1.00 L container, what is the concentration of CO(g) at equilibrium?
a. 1.12 mol/L
b. 0.371 mol/L
c. 0.445 mol/L
d. 0.748 mol/L