Chemistry: A Molecular Approach, 2e (Tro)
Chapter 14 Chemical Equilibrium
Multiple Choice Questions
1) Which of the following statements is FALSE?
A) When K >> 1, the forward reaction is favored and essentially goes to completion.
B) When K << 1, the reverse reaction is favored and the forward reaction does not proceed to a great
extent.
C) When K ≈ 1, neither the forward or reverse reaction is strongly favored, and about the same amount
of reactants and products exist at equilibrium.
D) K >> 1 implies that the reaction is very fast at producing products.
E) None of the above.
2) Give the direction of the reaction, if K >> 1.
A) The forward reaction is favored.
B) The reverse reaction is favored.
C) Neither direction is favored.
D) If the temperature is raised, then the forward reaction is favored.
E) If the temperature is raised, then the reverse reaction is favored.
3) Give the direction of the reaction, if K << 1.
A) The forward reaction is favored.
B) The reverse reaction is favored.
C) Neither direction is favored.
D) If the temperature is raised, then the forward reaction is favored.
E) If the temperature is raised, then the reverse reaction is favored.
4) Give the direction of the reaction, if K ≈ 1.
A) The forward reaction is favored.
B) The reverse reaction is favored.
C) Neither direction is favored.
D) If the temperature is raised, then the forward reaction is favored.
E) If the temperature is raised, then the reverse reaction is favored.
5) Express the equilibrium constant for the following reaction.
16 CH3Cl(g) + 8 Cl2(g) ⇔ 16 CH2Cl2(g) + 8 H2(g)
A) K =
B) K =
C) K =
D) K =
E) K =
6) The equilibrium constant is given for one of the reactions below. Determine the value of the missing
equilibrium constant.
H2(g) + Br2(g) ⇌ 2 HBr(g) Kc = 3.8 × 104
2 HBr(g) ⇌ H2(g) + Br2(g) Kc = ?
A) 1.9 × 104
B) 5.3 × 10-5
C) 2.6 × 10-5
D) 6.4 × 10-4
E) 1.6 × 103
7) The equilibrium constant is given for one of the reactions below. Determine the value of the missing
equilibrium constant.
H2(g) + Br2(g) ⇌ 2 HBr(g) Kc = 3.8 × 104
4 HBr(g) ⇌ 2 H2(g) + 2 Br2(g) Kc = ?
A) 1.9 × 104
B) 5.1 × 10-3
C) 2.6 × 10-5
D) 6.9 × 10-10
E) 1.6 × 103
8) The equilibrium constant is given for one of the reactions below. Determine the value of the missing
equilibrium constant.
2 SO2(g) + O2(g) ⇌ 2 SO3(g) Kc = 1.7 × 106
SO3(g) ⇌ 1/2 O2(g) + SO2(g) Kc = ?
A) 3.4 × 102
B) 8.5
C) 1.3 × 103
D) 1.2 × 10-6
E) 7.7 × 10-4
9) The equilibrium constant is given for two of the reactions below. Determine the value of the missing
equilibrium constant.
A(g) + B(g) ⇌ AB(g) Kc = 0.24
AB(g) + A(g) ⇌ A2B(g) Kc = 3.8
2 A(g) + B(g) ⇌ A2B(g) Kc = ?
A) 4.0
B) 0.91
C) 3.6
D) 16
E) 0.063
10) The equilibrium constant is given for two of the reactions below. Determine the value of the
missing equilibrium constant.
A(g) + 2B(g) ⇌ AB2(g) Kc = 59
AB2(g) + B(g) ⇌ AB3(g) Kc = ?
A(g) + 3B(g) ⇌ AB3(g) Kc = 478
A) 3.5 × 10-5
B) 2.8 × 104
C) 8.1
D) 0.12
E) 89
11) The equilibrium constant is given for two of the reactions below. Determine the value of the
missing equilibrium constant.
2A(g) + B(g) ⇌ A2B(g) Kc = ?
A2B(g) + B(g) ⇌ A2B2(g) Kc = 16.4
2A(g) + 2B(g) ⇌ A2B2(g) Kc = 28.2
A) 11.8
B) 0.00216
C) 0.582
D) 462
E) 1.72
12) What is Δn for the following equation in relating Kc to Kp?
2 SO2(g) + O2(g) ⇌ 2 SO3(g)
A) 3
B) -1
C) -2
D) 2
E) 1
13) What is Δn for the following equation in relating Kc to Kp?
N2O4(g) ⇌ 2NO2(g)
A) 3
B) -1
C) -2
D) 2
E) 1
14) What is Δn for the following equation in relating Kc to Kp?
C3H8(g) + 5 O2(g) ⇌ 3 CO2(g) + 4 H2O(l)
A) 3
B) -1
C) -3
D) 2
E) 1
15) What is Δn for the following equation in relating Kc to Kp?
4 NH3(g) + 3 O2(g) ⇌ 2 N2(g) + 6 H2O(g)
A) 3
B) -1
C) -2
D) 2
E) 1
16) What is Δn for the following equation in relating Kc to Kp?
SO3(g) + NO(g) ⇌ SO2(g) + NO2(g)
A) 0
B) -1
C) -2
D) 2
E) 1
17) In which of the following reactions will Kc = Kp?
A) 4 NH3(g) + 3 O2(g) ⇌ 2 N2(g) + 6 H2O(g)
B) SO3(g) + NO(g) ⇌ SO2(g) + NO2(g)
C) 2 N2(g) + O2(g) ⇌ 2 N2O(g)
D) 2 SO2(g) + O2(g) ⇌ 2 SO3(g)
E) None of the above reactions have Kc = Kp.
18) The reaction below has a Kp value of 3.3 x 10-5. What is the value of Kc for this reaction at 700 K?
2 SO3(g) ⇌ 2 SO2(g) + O2(g)
A) 5.7 × 10-7
B) 1.7 × 106
C) 3.3 × 10-5
D) 3.0 × 104
E) 1.9 × 10-3
19) Express the equilibrium constant for the following reaction.
P4(s) + 5 O2(g) ⇌ P4O10(s)
A) K =
B) K =
C) K = [O2]-5
D) K = [O2]5
E) K =
20) Express the equilibrium constant for the following reaction.
P4O10(s) ⇌ P4(s) + 5 O2(g)
A) K =
B) K =
C) K = [O2]-5
D) K = [O2]5
E) K =
21) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [P4O10]eq = 2.000 moles, [P4]eq = 3.000 moles, [O2]eq = 4.000 M
P4O10(s) ⇌ P4(s) + 5 O2(g)
A) 20.00
B) 4.000
C) 1.320
D) 1536
E) 1024
22) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [N2]eq = 3.6 M, [O2]eq = 4.1 M, [N2O]eq = 3.3 × 10–18 M.
2 N2(g) + O2(g) ⇌ 2 N2O(g)
A) 2.2 × 10-19
B) 4.5 × 1018
C) 2.0 × 10-37
D) 5.0 × 1036
E) 4.9 × 10-17
23) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [N2]eq = 1.5 M, [H2]eq = 1.1 M, [NH3]eq = 0.47 M.
N2(g) + 3 H2(g) ⇌ 2 NH3(g)
A) 3.5
B) 0.28
C) 9.1
D) 0.11
E) 0.78
24) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [HCl]eq = 0.13 M, [HI]eq = 5.6 × 10-16 M, [Cl2]eq = 0.0019 M.
2 HCl(g) + I2(s) ⇌ 2 HI(g) + Cl2(g)
A) 8.2 × 10-18
B) 2.8 × 1031
C) 1.2 × 1017
D) 1.4 × 10-19
E) 3.5 × 10-32
25) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [HCl]eq = 0.13 M, [HI]eq = 5.6 × 10-16 M, [Cl2]eq = 0.0019 M.
2 HI(g) + Cl2(g) ⇌ 2 HCl(g) + I2(s)
A) 8.2 × 10-18
B) 2.8 × 1031
C) 1.2 × 1017
D) 1.4 × 10-19
E) 3.5 × 10-32
26) Determine the value of Kp for the following reaction if the equilibrium concentrations are as
follows: P(CO)eq = 6.8 × 10-11 atm, P(O2)eq = 1.3 × 10-3 atm, P(CO2)eq = 0.041 atm.
2 CO(g) + O2(g) ⇌ 2 CO2(g)
A) 3.6 × 10-21
B) 2.8 × 1020
C) 4.6 × 1011
D) 2.2 × 10-12
E) 3.6 × 10-15
27) Calculate the value of [N2]eq if [H2]eq = 2.0 M, [NH3]eq = 0.5 M, and Kc = 2.
N2(g) + 3 H2(g) ⇌ 2 NH3(g)
A) 0.016 M
B) 0.031 M
C) 0.062 M
D) 0.40 M
E) 62.5 M
28) Calculate P [NO]eq, if P [NOCl]eq = 0.33 atm, P [Cl2]eq = 0.50 atm, and Kp = 1.9 x 10-2.
2 NOCl(g) ⇌ 2 NO(g) + Cl2(g)
A) 1.7 atm
B) 0.0042 atm
C) 0.30 atm
D) 0.064 atm
E) 0.087 atm
29) Which of the following statements is TRUE?
A) Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the reverse
reaction.
B) The equilibrium constant for the forward reaction is equal to the equilibrium constant for the reverse
reaction.
C) A reaction quotient (Q) larger than the equilibrium constant (K) means that the reaction will favor the
production of more products.
D) Dynamic equilibrium indicates that the amount of reactants and products are equal.
E) All of the above are true.
30) In a reaction mixture containing only reactants, what is the value of Q?
A) -1
B) 1
C) ∞
D) 0
E) It cannot be determined without concentrations.
31) In a reaction mixture containing only products, what is the value of Q?
A) -1
B) 1
C) ∞
D) 0
E) It cannot be determined without concentrations.
32) In a reaction mixture containing reactants and products, each at a concentration of 1M, what is the
value of Q?
A) -1
B) 1
C) ∞
D) 0
E) It cannot be determined without concentrations.
33) Which of the following statements is TRUE?
A) If Q < K, it means the reverse reaction will proceed to form more reactants.
B) If Q > K, it means the forward reaction will proceed to form more products.
C) If Q = K, it means the reaction is at equilibrium.
D) All of the above are true.
E) None of the above are true.
34) Which of the following statements is TRUE?
A) If Q < K, it means the reverse reaction will proceed to form more reactants.
B) If Q > K, it means the reverse reaction will proceed to form more reactants.
C) If Q = K, it means the reaction is not at equilibrium.
D) All of the above are true.
E) None of the above are true.
35) Which of the following statements is TRUE?
A) If Q < K, it means the forward reaction will proceed to form more products.
B) If Q > K, it means the forward reaction will proceed to form more products.
C) If Q = K, it means the reaction is not at equilibrium.
D) All of the above are true.
E) None of the above are true.
36) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a particular
temperature. Determine the equilibrium concentration of H2O(g).
C2H4(g) + H2O(g) ⇌ C2H5OH(g) Kc = 9.0 × 103
[C2H4]eq = 0.015 M [C2H5OH]eq = 1.69 M
A) 9.9 × 10-7 M
B) 80. M
C) 1.0 M
D) 1.68 M
E) 0.013 M
37) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a particular
temperature. Determine the equilibrium concentration of SO3(g).
2 SO2(g) + O2(g) ⇌ 2 SO3(g) Kc = 1.7 × 108
[SO2]eq = 0.0034 M [O2]eq = 0.0018 M
A) 1.9 M
B) 1.0 × 103 M
C) 0.53 M
D) 9.6 x 10-4 M
E) 0.73 M
38) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a particular
temperature. Determine the equilibrium concentration of SO3(g).
2 SO2(g) + O2(g) ⇌ 2 SO3(g) Kc = 1.7 × 108
[SO3]eq = 0.0034 M [O2]eq = 0.0018 M
A) 2.8 x 1013 M
B) 1.88 M
C) 6.1 x 10-6 M
D) 1.0 x 103 M
E) 1.4 M
39) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a particular
temperature. Determine the equilibrium pressure of H2.
D2(g) + H2(g) ⇌ 2 HD(g) Kp = 1.80
P(D2)eq = 1.1 × 10-3 atm P(HD)eq = 2.7 × 10-3 atm
A) 2.7 atm
B) 1.4 atm
C) 0.73 atm
D) 3.7 × 10-3 atm
E) 8.1 × 10-4 atm
40) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a particular
temperature. Determine the equilibrium pressure of CO.
CO(g) + 2 H2(g) ⇌ CH3OH(l) Kp = 2.25 × 104
P(H2)eq = 0.52 atm
A) 8.3 x 104 atm
B) 1.2 x 10-5 atm
C) 6.25 x 10-3 atm
D) 8.5 x 10-5 atm
E) 1.6 x 10-4 atm
41) Consider the following reaction:
Xe(g) + 2 F2(g) → XeF4(g)
A reaction mixture initially contains 2.24 atm Xe and 4.27 atm F2. If the equilibrium pressure of Xe is
0.34 atm, find the equilibrium constant (Kp) for the reaction.
A) 25
B) 0.12
C) 0.99
D) 8.3
E) 0.040
42) Consider the following reaction:
CH4(g) + 2 H2S(g) ⇌ CS2(g) + 4 H2(g)
A reaction mixture initially contains 0.50 M CH4 and 0.75 M H2S. If the equilibrium concentration of
H2 is 0.44 M, find the equilibrium constant (Kc) for the reaction.
A) 0.23
B) 0.038
C) 2.9
D) 10.
E) 0.34
43) Consider the following reaction:
COCl2(g) ⇌ CO(g) + Cl2(g)
A reaction mixture initially contains 1.6 M COCl2. Determine the equilibrium concentration of CO if
Kc for the reaction at this temperature is 8.33 × 10-4. Calculate this based on the assumption that the
answer is negligible compared to 1.6.
A) 4.2 × 10-4 M
B) 1.5 × 10-3 M
C) 3.7 × 10-2 M
D) 2.1 × 10-2 M
E) 1.3 × 10-3 M
44) Consider the following reaction:
CuS(s) + O2(g) ⇌ Cu(s) + SO2(g)
A reaction mixture initially contains 2.9 M O2. Determine the equilibrium concentration of O2 if Kc for
the reaction at this temperature is 1.5.
A) 1.9 M
B) 1.7 M
C) 2.2 M
D) 1.2 M
E) 0.59 M
45) Consider the following reaction:
2 H2O(g) + 2 SO2(g) ⇌ 2 H2S(g) + 3 O2(g)
A reaction mixture initially contains 2.8 M H2O and 2.6 M SO2. Determine the equilibrium
concentration of H2S if Kc for the reaction at this temperature is 1.3 × 10-6.
A) 0.045 M
B) 0.058 M
C) 0.028 M
D) 3.1 × 10-3 M
E) 0.12 M
46) Consider the following reaction:
CO2(g) + C(graphite) ⇌ 2 CO(g)
A reaction mixture initially contains 0.56 atm CO2 and 0.32 atm CO. Determine the equilibrium
pressure of CO if Kp for the reaction at this temperature is 2.25.
A) 0.83 atm
B) 0.31 atm
C) 0.26 atm
D) 0.58 atm
E) 0.42 atm
47) Consider the following reaction:
NO(g) + SO3(g) ⇌ NO2(g) + SO2(g)
A reaction mixture initially contains 0.86 atm NO and 0.86 atm SO3. Determine the equilibrium
pressure of NO2 if Kp for the reaction at this temperature is 0.0118.
A) 0.78 atm
B) 0.084 atm
C) 0.012 atm
D) 0.85 atm
E) 0.048 atm
48) The following reaction is exothermic. Which change will shift the equilibrium to the left?
2 SO2(g) + O2(g) ⇌ 2 SO3(g)
A) raising the temperature
B) adding SO3
C) removing O2
D) all of the above
E) none of the above
49) The following reaction is exothermic. Which change will shift the equilibrium to the left?
2 SO2(g) + O2(g) ⇌ 2 SO3(g)
A) raising the temperature
B) decrease pressure
C) increase volume
D) all of the above
E) none of the above
50) Consider the following reaction at equilibrium. What effect will adding more SO3 have on the
system?
SO2(g) + NO2(g) ⇌ SO3(g) + NO(g)
A) The reaction will shift in the direction of products.
B) The reaction will shift to decrease the pressure.
C) No change will occur since SO3 is not included in the equilibrium expression.
D) The reaction will shift in the direction of reactants.
E) The equilibrium constant will decrease.
51) Consider the following reaction at equilibrium. What effect will removing NO2 have on the
system?
SO2(g) + NO2(g) ⇌ SO3(g) + NO(g)
A) The reaction will shift in the direction of products.
B) The reaction will shift to decrease the pressure.
C) No change will occur since SO3 is not included in the equilibrium expression.
D) The reaction will shift in the direction of reactants.
E) The equilibrium constant will decrease.
52) Consider the following reaction at equilibrium. What effect will adding more H2S have on the
system?
2 H2S(g) + 3 O2(g) ⇌ 2 H2O(g) + 2 SO2(g)
A) The reaction will shift to the left.
B) No change will be observed.
C) The equilibrium constant will decrease.
D) The equilibrium constant will increase.
E) The reaction will shift in the direction of products.
53) Consider the following reaction at equilibrium. What effect will removing H2O have on the
system?
2 H2S(g) + 3 O2(g) ⇌ 2 H2O(g) + 2 SO2(g)
A) The reaction will shift to the left.
B) No change will be observed.
C) The equilibrium constant will decrease.
D) The equilibrium constant will increase.
E) The reaction will shift in the direction of products.
54) Consider the following reaction at equilibrium. What effect will increasing the volume of the
reaction mixture have on the system?
2 H2S(g) + 3 O2(g) ⇌ 2 H2O(g) + 2 SO2(g)
A) The reaction will shift to the right in the direction of products.
B) No effect will be observed.
C) The reaction will shift to the left in the direction of reactants.
D) The equilibrium constant will decrease.
E) The equilibrium constant will increase.
55) Consider the following reaction at equilibrium. What effect will increasing the pressure of the
reaction mixture have on the system?
2 H2S(g) + 3 O2(g) ⇌ 2 H2O(g) + 2 SO2(g)
A) The reaction will shift to the right in the direction of products.
B) No effect will be observed.
C) The reaction will shift to the left in the direction of reactants.
D) The equilibrium constant will decrease.
E) The equilibrium constant will increase.
56) Consider the following reaction at equilibrium. What effect will adding 1 mole of Ar to the reaction
mixture have on the system?
2 H2S(g) + 3 O2(g) ⇌ 2 H2O(g) + 2 SO2(g)
A) The reaction will shift to the right in the direction of products.
B) No effect will be observed.
C) The reaction will shift to the left in the direction of reactants.
D) The equilibrium constant will decrease.
E) The equilibrium constant will increase.
57) Consider the following reaction at equilibrium. What effect will adding some C have on the system?
CO2(g) + C(graphite) ⇌ 2 CO(g)
A) No effect will be observed since C is not included in the equilibrium expression.
B) The equilibrium constant will decrease.
C) The reaction will shift to the left in the direction of reactants.
D) The equilibrium constant will increase.
E) The reaction will shift to the right in the direction of products.
58) Consider the following reaction at equilibrium. What effect will adding CO2 have on the system?
CO2(g) + C(graphite) ⇌ 2 CO(g)
A) No effect will be observed since CO2 is not included in the equilibrium expression.
B) The equilibrium constant will decrease.
C) The reaction will shift to the left in the direction of reactants.
D) The equilibrium constant will increase.
E) The reaction will shift to the right in the direction of products.
59) Consider the following reaction at equilibrium. What effect will reducing the volume of the reaction
mixture have on the system?
CuS(s) + O2(g) ⇌ Cu(s) + SO2(g)
A) The equilibrium constant will decrease.
B) No effect will be observed.
C) The reaction will shift to the right in the direction of products.
D) The equilibrium constant will increase.
E) The reaction will shift to the left in the direction of reactants.
60) Consider the following reaction at equilibrium. What effect will increasing the pressure of the
reaction mixture have on the system?
CuS(s) + O2(g) ⇌ Cu(s) + SO2(g)
A) The equilibrium constant will decrease.
B) No effect will be observed.
C) The reaction will shift to the right in the direction of products.
D) The equilibrium constant will increase.
E) The reaction will shift to the left in the direction of reactants.
61) Consider the following reaction at equilibrium. What effect will reducing the volume of the reaction
mixture have on the system?
Xe(g) + 2 F2(g) → XeF4(g)
A) The reaction will shift to the left in the direction of reactants.
B) The equilibrium constant will increase.
C) No effect will be observed.
D) The reaction will shift to the right in the direction of products.
E) The equilibrium constant will decrease.
62) Consider the following reaction at equilibrium. What effect will reducing the pressure of the
reaction mixture have on the system?
Xe(g) + 2 F2(g) → XeF4(g)
A) The reaction will shift to the left in the direction of reactants.
B) The equilibrium constant will increase.
C) No effect will be observed.
D) The reaction will shift to the right in the direction of products.
E) The equilibrium constant will decrease.
63) Consider the following reaction at equilibrium. What effect will increasing the temperature have on
the system?
Fe3O4(s) + CO(g) ⇌ 3 FeO(s) + CO2(g) ΔH°= +35.9 kJ
A) The reaction will shift to the left in the direction of reactants.
B) The equilibrium constant will increase.
C) The equilibrium constant will decrease.
D) No effect will be observed.
E) The reaction will shift to the right in the direction of products.
64) Consider the following reaction at equilibrium. What effect will decreasing the temperature have on
the system?
CO2(g) + 2 H2O(l) ⇌ CH4(g) + 2 O2(g) ΔH° = +890 kJ
A) The reaction will shift to the left in the direction of reactants.
B) The equilibrium constant will decrease.
C) The equilibrium constant will increase.
D) The reaction will shift to the right in the direction of products.
E) No effect will be observed.
65) Consider the following reaction at equilibrium. What effect will increasing the temperature have on
the system?
C3H8(g) + 5 O2(g) ⇌ 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ
A) The reaction will shift to the right in the direction of products.
B) The reaction will shift to the left in the direction of reactants.
C) The equilibrium constant will increase.
D) The equilibrium constant will decrease.
E) No effect will be observed.