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1. Which of the following is equal for the forward and reverse reactions at equilibrium?
A) concentration
B) rates
C) rate constants
2. All chemical equilibria are _____ in nature.
A) dynamic
B) equal
C) static
D) kinetic
3. An example of a physical equilibrium is _____.
A)
B)
C)
D)
4. Which of the following is not a physical equilibrium?
A) melting
B) allotropic transformation
C) vaporization
D) rusting
5. An example of heterogeneous equilibrium is _____.
A)
B)
C) Enzyme-catalyzed reactions
6. Which of the following statements is always correct?
A) chemical equilibria are homogeneous
B) physical equilibria are homogeneous
C) physical equilibria are heterogeneous
D) chemical equilibria are heterogeneous
7. The expression for Kp for the reaction
is _____.
A) PCO 2
B)
P H 2O
C) PCO 2
/ P H 2O
D) PCO 2
· P H 2O
8. The expression for Kp for the reaction
is _____.
A)
B)
C)
D)
2P SO2 + P O2
P2 SO2 · P O2
P SO2 + P O2
2P SO2 / P O2
9. The equilibrium constant Kp is not applicable for the reaction _____.
A)
B)
C)
D)
10. The equilibrium constant Kc for the reaction
is given by _____.
A)
B)
C)
D)
11. The equation relating Kp and Kc is _____.
A) Kp = Kc (RT)n
B) Kp = Kc RTn
C) Kc = Kp RTn
D) Kc = Kp (RT)n
12. Kp will be equal to Kc if _____.
A) n = 1
B) n = 0
C) RT = 0
D) n = 
13. Kp will be less than Kp if _____.
A) H = negative
B) n = positive
C) n = negative
D) n = 0
14. The equilibrium constants for the reactions
and
are x and y, respectively. The equilibrium constant for the reaction
is _____.
A)
B) x + y
C) x – y
D) xy
Use the following to answer questions 15-16:
The equilibrium constant for the reaction
is x.
15. The equilibrium constant for the reaction
is _____.
A)
B)
C)
D)
16.
–x
x
1/x
2x
The equilibrium constant for the reaction
A) 2x
B) x
C) x/2
D) x2
is _____.
17. The equilibrium constant for the reaction
is 4.17  10
31
. The equilibrium constant for the reaction
is
A) –4.17  1031
B) 4.17  1031
C) 2.40  1030
D) 2.40 10-33
18. The number of moles of H2, S2, and H2S present at the equilibrium for the reaction
are 2.50, 1.35  10-5 and 8.70 moles respectively in a 12 L flask. The equilibrium
constant, Kc for the reaction is _____.
A) 1.08  107
B) 1.08  10-7
C) 5.6  103
D) 7.2  10-5
19. Kc for the reaction
is 2.24  1022 at 1273 ºC. Kp for the reaction at the same temperature is _____.
A) 7.16  10-18
B) 1.76  1020
C) 5.12  10-15
D) 3.12  1019
20. The equilibrium partial pressures of N2, O2 and NO in the reaction
are 0.15, 0.33 and 0.050 atm, respectively at 2200°C. The value of Kp for the reaction is
_____.
A) 5.1
B) 0.51
C) 51
D) 0.051
21. The equilibrium concentrations of NH3, N2 and H2 are 0.25 M, 0.11 M and 1.91 M,
respectively. The equilibrium constant Kc for the reaction
is _____.
A)
B)
C)
D)
0.082
8.2  10-3
8.2
0.82
22. The equilibrium constant, Kc, for the reaction
is 0.082. What is Ka for
A)
B)
C)
D)
0.164
0.041
0.29
1.64
23. The equilibrium constant, Kc , for the reaction
is 3.8  10-5 at 727°C. The value of Kp for the equilibrium
at the same temperature is _____.
A)
B)
C)
D)
648
320
32.0
6.48
24. The equilibrium pressure for the reaction
is 0.105 atm at 350°C. Kp for the reaction is
_____.
A) 0.105
B) 0.210
C) 1.05
D) 10.5
25. Kp for the reaction
at 350oC is 0.105. Kc for the reaction at the
same temperature is _____.
A) 4.21  103
B) 0.105
C) 3.05  10-4
D) 2.05  10-3
26. The equilibrium constant, Kp, for the reaction
is 1.05 at 250°C. The reaction is started with PCl5, PCl3 and Cl2 at 0.177, 0.223 and
0.111 atm at 250°C. When the reaction comes to equilibrium, the pressure of _____.
A) PCl3 must have decreased
B) Cl2 must have decreased
C) PCl5 must have decreased
D) PCl5 must have increased
27. Starting with only the solid, the total pressure of NH3 and CO2 was found to 0.363 atm
for the equilibrium
equilibrium constant, Kp is
A) 7.1  10-3
B) 2.5  10-2
C) 5.3  10-4
D) 3.6  10-6
at 40°C. The
28. 1.05 moles of Br2 in a 0.980 L container undergo 1.2% dissociation. The equilibrium
constant, Kc for the reaction
A) 2.5  10-5
B) 1.8  10-3
C) 6.2  10-4
D) 5.9  10-6
is _____.
29. Kp = Kc for the reaction _____.
A)
B)
C)
D)
30. 3.00  10-2 mol of phosgene gas, COCl2, was heated in a 1.50 L container at 800 K. At
equilibrium the pressure of CO was found to be 0.497 atm. The equilibrium constant, Kp
for the reaction
A) 3.30
B) 9.80
C) 2.75
D) 5.61
is _____.
31. The equilibrium constant, Kp for the reaction
at 2200°C is 0.051. The equilibrium constant, Kc for the same reaction is _____.
A) 0.102
B) 0.051
C) 2.5  10-3
D) 1.02  104
Use the following to answer questions 32-33:
At equilibrium, nitrosyl bromide in the reaction
is 34% dissociated at 25°C and the total pressure is 0.25 atm.
32. The value of Kp for the reaction is _____.
A) 9.6  10-3
B) 1.39  10-5
C) 3.8  10-4
D) 6.7  10-6
33. The value of Kc for the above reaction is _____.
A) 1.6  10-6
B) 2.7  10-5
C) 3.9 10-4
D) 4.5  10-7
34. 2.50 mole of NOCl was heated in a 1.50 L vessel at 400°C.At equilibrium it was found
that 28.0% of the NOCl had dissociated. The equilibrium constant, Kc of the reaction
is _____.
A)
B)
C)
D)
0.0353
3.53  102
3.53  10-4
3.53
35. The ionization constants Kc' and Kc” for
were found to be 9.5  10-8 and 1.0  10-19 respectively. The equilibrium constant for
the reaction
is _____.
A)
B)
C)
D)
9.5  10
1.0  10-19
9.5  10-27
1.05  10-12
-8
36. The equilibrium constant, Kc = 4.0 × 10-6 for the reaction
.
If the equilibrium constant, Kc= 6.5  10-2 for the reaction
,
the equilibrium constant for
is _____.
A)
B)
C)
D)
4.0 10-6
6.1  10-5
1.6  104
6.5  10-2
Use the following to answer questions 37-38:
The following equilibrium constants were measured for the reactions:
37. The equilibrium constant for the reaction
is _____.
A)
B)
C)
D)
xy
x+y
xy2
x + y2
38. The equilibrium constants K1 and K2 for the reactions above are
1.3  1014 and 6.0  10-3, respectively. The equilibrium constant for the reaction
is _____.
A)
B)
C)
D)
4.7  109
1.0  1014
1.0  1026
3.6  1018
39. The equilibrium constants K1 K2 and K3 for the reactions below are
K1 = 4.2  1052
K2 = x
K3 = 5.6  1023.
The value of K2 is _____.
A) 9.8  1028
B) 9.8  10128
C) 6.7  1012
D) 2.6  1075
40. The equilibrium constant in terms of rate constants for the forward reaction, kf, and the
reverse reaction, kr, is given as _____.
A)
k
K= r
kf
B) K = kf + kr
C)
kf
K
kr
D) K = kf kr
41. The concentration of H+ in pure water at 25°C is _____.
A) 10-14 M
B) 10-7 M
C) 10-10 M
D) 10-8 M
42. The equilibrium constant of a reaction is 12.6. If the rate constant of the reverse
reaction is 5.1  10-2, the rate constant for the forward reaction is _____.
A) 0.32
B) 0.16
C) 0.64
D) 0.08
43. Which of the following statements can be correct with respect to reaction quotient, Q
and equilibrium constant, K?
A) Q < K
B) Q = K
C) Q > K
D) all the above
44. The value of Kc for the equilibrium
is 5.6  104 350°C. The initial pressures of SO2 and O2 in a mixture are 0.350 atm and
0.762 atm. The total pressure at equilibrium will be _____ atm.
A) less than 0.350
B) less than 0.741
C) less than 1.112
D) equal to 1.112
45.
The value of Kc for the reaction
is 1.2 . The
reaction is started with [H2 ]0 = 0.76 M, [N2]0 = 0.60 M and [NH3]0= 0.48 M. Which of
the following is correct as the reaction comes to equilibrium?
A) The concentration of N2will increase
B) The concentration of H2will decrease
C) The concentration of NH3will decrease
D) The concentration of both N2and H2will increase
Use the following to answer questions 46-48:
For the reaction
Kc = 0.534 at 700°C
46. Calculate the number of moles of H2 present at equilibrium if a mixture of 0.300 moles
of CO and 0.300 moles of H2O is heated to 700°C in a 10.0 L container.
A) 0.432 mol
B) 0.273 mol
C) 0.577 mol
D) 0.173 mol
47. Which statement is correct with respect to the above equilibrium when 0.30 moles of
CO and 0.30 moles of H2O are heated to 700°C and allowed to reach equilibrium.
A) [H2O] = [CO2]
B) [CO2] = [CO]
C) [H2O] = [CO]
D) [H2O] = [H2]
48. Which of the following statements is correct?
A) All concentrations are equal
B) Kp = Kc
C) Kp < Kc
D) Kp > Kc
49. Kp is 158 for the equilibrium
Starting with NO2 (g) only, the partial pressure of O2 at equilibrium is 0.25 atm.
Calculate the partial pressure of NO2 at equilibrium.
A) 0.020 atm
B) 0.20 atm
C) 3.1 atm
D) 0.035atm
50. The partial pressure of NO in the above equilibrium is _____ atm.
A) 0.125
B) 0.50
C) 0.25
D) 0.02
51.
52.
The equilibrium constant Kc for the reaction
is
2.18  106. Starting with 3.20 moles of HBr in a 12.0L container, the concentration of
HBr at equilibrium is _____.
A) 0.167 M
B) 0.0267 M
C) 1.6 M
D) 0.267 M
Kc is 3.8 10-5 at 1000K for the equilibrium
Starting with 0.0456 moles of I2 in a 2.30 L flask, at 1000 K, the equilibrium
concentration of I2 at is:
A) 1.94 M
B) 0.0194 M
C) 0.12 M
D) 0.012 M
Use the following to answer questions 53-54:
Kc for the reaction
is 4.63  10-3 at 527°C .
53. Starting with pure phosgene, COCl2, at 0.760 atm, the equilibrium partial pressure of
CO is _____.
A) 0.352 atm
B) 0.0416 atm
C) 0.0352 atm
D) 0.416 atm
54. Starting with pure phosgene, COCl2, at 0.760 atm, the equilibrium partial pressure of
COCl2 is _____.
A) 0.173 atm
B) 0.204 atm
C) 0.302 atm
D) 0.408 atm
55. What is the value of Kc for the reaction
when the equilibrium concentrations of
CO, H2, CO2 and H2O are 0.050 M, 0.045 M, 0.086 M and 0.040 M respectively?
A) 0.074
B) 0.52
C) 0.063
D) 0.24
Use the following to answer questions 56-57:
The equilibrium constant Kp for the reaction
at equilibrium is 4.50 atm.
is 1.52 and the total pressure
56. The equilibrium partial pressure of CO is _____ atm.
A) 0.86
B) 1.62
C) 1.96
D) 1.31
57. The equilibrium partial pressure of CO2 is _____ atm.
A) 2.54 atm
B) 0.98 atm
C) 1.27 atm
D) 0.72 atm
Use the following to answer questions 58-60:
The equilibrium constant, Kc for the reaction
0.80 mole of H2 and 0.80 mole CO2 are placed in a 5.0 L flask.
58. The concentration of H2 at equilibrium is _____.
A) 0.054 M
B) 0.025 M
C) 0.15 M
D) 0.029 M
is 4.2. Initially
59. At equilibrium, the concentration of H2 is equal to the concentration of _____.
A) H2O
B) CO
C) CO2
D) H2O + CO2
60. The concentration of CO at equilibrium is _____.
A) 0.22M
B) 0.056M
C) 0.021M
D) 0.11M
61. Le Châtelier's principle can help to predict how to maximize _____.
A) Reaction yield
B) Equilibrium constant
C) Temperature
D) Rate constant
62. Which can alter the value of the equilibrium constant?
A) Catalyst
B) Concentration
C) Pressure
D) Temperature
63. The equilibrium position of the reaction
can be shifted in the forward direction
by _____.
A) Removing SO2
B) Adding Cl2
C) Removing Cl2
D) Removing SO2 and Cl2
Use the following to answer questions 64-65:
The equilibrium constant Kc for the equilibrium
is x.
64. The equilibrium constant for the reaction
is _____.
A)
B)
C)
D)
x/2
x1/2
x2
2x
65. The equilibrium constant for the reaction
A) x2
B)
is _____.
C) x–2
D) –2x
66. Which of the following equilibria is not affected by pressure?
A)
B)
C)
D)
67. The equilibrium
formation by _____. H = 92.5 kJ.
A) Increasing temperature
B) Increasing pressure
C) Decreasing temperature
D) Increasing the concentration PCl3
, can be shifted toward more product
68. The equilibrium
can shifted to the reactant side by _____. H = –
198.2 kJ
A) Decreasing temperature
B) Decreasing volume
C) Decreasing pressure
D) Increasing the concentration of SO2
69. The equilibrium pressure of NO in the equilibrium
2
atm. Its pressure on the addition of a catalyst will be _____.
A) 1.06 atm
B) 0.75 atm
C) 1.56 atm
D) 2.71 atm
70.
71.
The position of the equilibrium
to the left by the addition of _____ at constant pressure.
A) CO
B) He
C) O2
D) KCl
The addition of He to the equilibrium
constant volume _____.
A) Shifts the equilibrium to the left
B) Increases Kc
C) Shifts the equilibrium to the right
D) Has no effect
is 1.56
can be shifted
at
72. Which of the following will shift the equilibrium
to the right?
A)
B)
C)
D)
Decrease of temperature
Addition of KCl
Addition of CO2
Addition of NaOH solution
73.
The equilibrium
by _____.
A) increasing temperature
B) decreasing pressure
C) removing some CO2
D) all of the above
can be shifted to the right
Use the following to answer questions 74-76:
Pure NOCl gas was heated to 240 °C in a 1.00-L container. At equilibrium the total pressure was 1.00 atm and
the NOCl pressure was 0.64 atm.
74. The partial pressure of NO at equilibrium in the reaction
is _____ atm.
A)
B)
C)
D)
0.24
0.12
0.34
0.17
75. The partial pressure of Cl2 in the equilibrium
is _____ atm.
A)
B)
C)
D)
0.36
0.09
0.12
0.18
76. Kp for the equilibrium
is _____.
A)
B)
C)
D)
1.7
0.12
0.17
0.017
Use the following to answer questions 77-78:
Kp is 2.9  10-11 at 530°C for the reaction
.
77. What is the partial pressure of NO at equilibrium when the equilibrium partial pressures
of N2 and O2 are 3.0 atm and 0.012 atm, respectively?
A) 1.0 10–6 atm
B) 1.6 10–3 atm
C) 1.6 10–2 atm
D) 0.16 atm
78. What is the partial pressure of NO at equilibrium under atmospheric conditions where
the partial pressures of N2 and O2 are 0.78 atm and 0.21 atm at 25°C? Kp for the reaction
is 4.010-31 at 25 °C.
A) 1.12 10-12 atm
B) 2.6 10-16 atm
C) 1.3 10-8 atm
D) 1.45  10-4 atm
79. The thermal decomposition of NaHCO3(s) is favored by _____.
A) decreasing temperature
B) increasing temperature
C) increasing pressure
D) adding CO2
80. Kp < Kc at 25 °C for which of the reactions below?
A)
B)
C)
D)
81. The condition for maximum yield of NOCl2 in the reaction
0
is _______. ( H f of NOCl = 51.7 kJ/mol,
H 0f
of NO = 90.4kJ/mol.)
A)
B)
C)
D)
high pressure, high temperature
low pressure, low temperature
low pressure, high temperature
high pressure, low temperature
82. For the reaction
PA = 0.60 atm and PB = 0.60 atm at equilibrium at some temperature. Kp for the reaction
is _____.
A) 1
B) 0.5
C) 1.7
D) 0.6
83. For the reaction
at equilibrium, the PA=0.60 atm and PB=0.60 atm and the total pressure is 1.2 atm. What
is the PA when the total pressure is increased to 1.5 atm?
A) 0.69 atm
B) 0.81 atm
C) 0.75 atm
D) 0.91 atm
84. The equilibrium mixture in the reaction
consists of 0.020 mole O2, 0.040 mole NO and 0.96 mole NO2. What is Kp for the
reaction at 430°C and at a total pressure of 0.20 atm?
A) 1.5 105
B) 7.2 104
C) 8.1 10–3
D) 5.6 10–6
85. Ammonium carbamate decomposes at a certain temperature .The equilibrium pressure
of the reaction
is 0.318 atm. Kp for the reaction is _____.
A) 5.92 10-5
B) 1.26 10-4
C) 3.12 10-6
D) 4.76 10-3
Use the following to answer questions 86-88:
A mixture of 0.47 moles of H2 and 3.59 moles of HCl is heated to 2800°C and allowed to reach equilibrium.
The total pressure at equilibrium is 2.00 atm.
Kp = 193 at 2800°C.
86. The equilibrium pressure of H2 is _____ atm.
A) 0.56 atm
B) 0.28 atm
C) 0.049 atm
D) 1.67 atm
87. The partial pressure of Cl2 in the above equilibrium is _____ atm.
A) 0.28 atm
B) 0.049 atm
C) 0.56 atm
D) 0.49 atm
88. The partial pressure of HCl in the above equilibrium is _____ atm.
A) 1.28 atm
B) 1.01 atm
C) 2.06 atm
D) 1.67 atm
89. Initially 1 mole of N2O4 is placed in a vessel and allowed to reach equilibrium. The
relation between the degree of dissociation , total pressure P and Kp for the reaction
is _____.
4
P
1 2
B)
4 2
Kp 
P
(1   )2
C)
2
Kp 
P
1 2
D)
2 2
Kp 
P
2
1   
A)
Kp 
2
90. One mole of N2 and three moles of H2 are placed in a flask and allowed to reach
equilibrium. T = 375 ºC. The mole fraction of NH3 at equilibrium is found to be 0.21.
What is the total pressure of the system at equilibrium?
A)
B)
C)
D)
50 atm
5 atm
500 atm
0.5 atm
91. What is [S2] at equilibrium in the following reaction if [H2S] = 4.84  10-3 M and [H2] =
1.50  10-3 M at equilibrium?
A)
B)
C)
D)
2.34  10-2
0.234 M
2.34  10-3M
2.34  10-4M
Kc = 2.25  10-4
92. 6.75 g of SO2Cl2 was placed in a 2.00L flask. At 648 K 0.0345 moles of SO2 was
present. Kc for the reaction
A) 3.83 10-2
B) 4.71  10-3
C) 1.12  10-2
D) 6.12  10-4
is _____.
Use the following to answer questions 93-95:
Kp for the reaction
at 375°C is 4.31  10-4. The reaction is started with
0.373 atm of H2 and 0.862 atm of N2 in a constant volume vessel.
93. The partial pressure of N2 at equilibrium is _____ atm.
A) 0.260
B) 0.760
C) 0.860
D) 0.960
94. The partial pressure of H2 at equilibrium is _____ atm.
A) 0.366
B) 0.166
C) 0.266
D) 0.566
95. The partial pressure of NH3 at equilibrium is _____ atm.
A) 4.40  10-3
B) 1.12  10-2
C) 7.20  10-4
D) 2.70  10-5
Use the following to answer questions 96-97:
A 0.244 M fructose solution was prepared and it was found that at equilibrium the fructose concentration had
decreased to 0.113 M.
96.
The equilibrium constant for the reaction
A) 2.06
B) 5.16
C) 4.27
D) 1.16
is _____.
97. The percentage of fructose converted into glucose in the equilibria
is _____.
A)
B)
C)
D)
53.7%
83.1%
21.7%
63.2%
Use the following to answer questions 98-99:
The equilibrium pressure of oxygen for the reaction
is 0.49 atm .
98. Kp for the reaction is _____.
A) 0.49
B) 2.5  10-3
C) 0.98
D) 4.9
99. The fraction of CuO that will decompose if 0.16 mole of CuO is placed in a 2.0 L vessel
at 1024°C is _____.
A) 0.15
B) 0.71
C) 0.23
D) 0.47
100. 3.9 moles of NO and 0.88 moles of CO2 are allowed to react as
At equilibrium 0.11 moles of CO2 was present. Kc for the reaction is _____.
A) 0.27
B) 1.7
C) 3.14
D) 6.03
Use the following to answer questions 101-102:
For the reaction at 430°C,
Kc = 54.3.
Initially 0.714 moles of H2 and 0.984 moles of I2 and 0.886 moles of HI are placed in a 2.40 L vessel.
101. The equilibrium concentration of H2 is _____.
A) 0.070 M
B) 0.182 M
C) 0.152 M
D) 0.012 M
102. The equilibrium concentration of I2 is _____.
A) 0.112
B) 0.082
C) 0.182
D) 0.116
103.
A gaseous compound, A, dissociates as follows:
. A was
heated until equilibrium was reached. The pressure of A at equilibrium was 0.14P,where
P is the total pressure. Kp for the reaction is _____.
A) 0.13P
B) 1.3P
C) 0.013P
D) 13P
Use the following to answer questions 104-106:
For the reaction
Kc = 1.2 at 375°C.
104. Kp for the reaction is _____.
A) 4.2  10-2
B) 1.2 102
C) 3.1  10-3
D) 4.2  10-4
105. K for the reaction
c
A) –1.2
B) 0.83
C) 0.38
D) 0.012
is _____.
106. Kc for the formation of one mole of NH3 from H2 and N2 is _____.
A) 0.6
B) 1.1
C) 1.2
D) 2.2
Use the following to answer questions 107-108:
The vapor pressure of water at 20°C is 0.0231 atm.
107.
Kp for the process
A) 0.0231
B) 2.31  10-6
C) 2.31
D) 100
is _____.
108. Kc for vaporization of water is_____.
A) 1.8  10-2
B) 2.3  10-5
C) 9.6  10-4
D) 3.6  10-3
Use the following to answer questions 109-110:
The density of a mixture of the gases, NO2 and N2O4, is 2.3 g/L at 74°C and 1.3 atm.
109. The partial pressure of NO2 in the mixture is _____ atm.
A) 1.2
B) 0.12
C) 0.012
D) 0.24
110. The partial pressure of N2O4 the mixture is _____ atm.
A) 0.62
B) 0.12
C) 0.062
D) 0.63
111. What is Kp for the reaction
equilibrium is 2.2 atm?
A) 1.1
B) 1.2
C) 2.2
D) 2.1
when the total pressure at
Use the following to answer questions 112-114:
For the equilibrium
0.20 atm at 25°C.
, the equilibrium partial pressures of NO2 and N2O4 are 0.15 and
112. What is the equilibrium partial pressure of NO2 when the volume is doubled?
A) 1.0atm
B) 0.10atm
C) 10atm
D) 0.01atm
113. The equilibrium partial pressure of N2O4 when the volume is doubled will be _____
atm.
A) 0.88
B) 0.44
C) 0.044
D) 0.088
114. Kp for the equilibrium
A) 1.13
B) 0.113
C) 11.3
D) 1.13 104
at 25°C is _____.
115. The vapor pressure of mercury is 0.0020 mmHg at 26°C. Kc for the process
, is _____.
A)
B)
C)
D)
1.1  10
2.2  104
1.1  10-3
4.4  10-2
-7
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
B
A
C
D
A
C
D
B
B
C
A
B
C
D
C
D
C
A
B
D
A
C
B
A
D
C
A
C
D
A
B
A
C
A
C
B
C
A
B
C
B
C
D
C
B
D
C
B
A
B
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
100.
101.
102.
D
B
A
D
B
C
A
A
C
D
A
D
B
B
C
A
A
C
C
B
D
D
D
A
C
D
A
B
B
A
D
C
A
A
D
B
B
D
A
A
C
A
C
A
A
D
A
A
C
B
A
C
103.
104.
105.
106.
107.
108.
109.
110.
111.
112.
113.
114.
115.
B
D
B
B
A
C
A
B
B
B
D
B
A
Chapter 14 Chemical Equilibrium
Student: ___________________________________________________________________________
1.
Which is the correct equilibrium constant expression for the following reaction?
Fe2O3(s) + 3H2(g)
A.
B.
C.
D.
E.
2.
Br2(g) + 5F2(g) is
Kc =[Br2] [F2]/[BrF5]
Kc = [Br2] [F2]5/[BrF5]2
Kc = [Br2] [F2]2/[BrF5]5
Kc = [BrF5]2/[Br2][F2]5
Kc = 2[BrF5]2/([Br2]  5[F2]5)
The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to
completion (least  greatest tendency).
A.
B.
C.
D.
E.
4.
Kc = [Fe2O3] [H2]3/[Fe]2[H2O]3
Kc = [H2]/[H2O]
Kc = [H2O]3/[H2]3
Kc = [Fe]2[H2O]3/[Fe2O3] [H2]3
Kc = [Fe] [H2O]/[Fe2O3] [H2]
The equilibrium constant expression for the reaction 2BrF5(g)
A.
B.
C.
D.
E.
3.
2Fe(s) + 3H2O(g)
2<1<3
1<2<3
2<3<1
3<2<1
3<1<2
Consider the two gaseous equilibria
The values of the equilibrium constants K1 and K2 are related by
A.
B.
C.
D.
E.
K2 = K12
K22 = K1
K2 = 1/K12
K2 = 1/K1
none of these
5.
Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and
chlorine.
CCl4(g) + (1/2)O2(g)
COCl2(g) + Cl2(g), Kc = 4.4  109 at 1,000 K
Calculate Kc for the reaction 2CCl4(g) + O2(g)
A.
B.
C.
D.
E.
6.
4.4  109
8.8  109
1.9  1010
1.9  1019
2.3  10-10
The equilibrium constant for the reaction Ni(s) + 4CO(g)
the equilibrium constant for the reaction Ni(CO)4(g)
A.
B.
C.
D.
E.
7.
Ni(CO)4(g) is 5.0  104 at 25ºC. What is
Ni(s) + 4CO(g)?
2.0  10-5
2.5  109
5.0  104
5.0  10-4
2.0  10-3
Which of these statements is true about chemical equilibria in general?
A.
B.
C.
D.
E.
8.
2COCl2(g) + 2Cl2(g).
At equilibrium the total concentration of products equals the total concentration of reactants, that is,
[products] = [reactants].
Equilibrium is the result of the cessation of all chemical change.
There is only one set of equilibrium concentrations that equals the Kc value.
At equilibrium, the rate constant of the forward reaction is equal to the rate constant for the reverse
reaction.
At equilibrium, the rate of the forward reaction is equal to as the rate of the reverse reaction.
The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to
completion (least completion greatest completion).
A.
B.
C.
D.
E.
2<1<3<4
3<1<4<2
3<4<1<2
4<3<2<1
4<3<1<2
9.
When the following reaction is at equilibrium, which of these relationships is always true?
2NOCl(g)
A.
B.
C.
D.
E.
2NO(g) + Cl2(g)
[NO][Cl2] = [NOCl]
[NO]2[Cl2] = [NOCl]2
[NOCl] = [NO]
2[NO] = [Cl2]
[NO]2[Cl2] = Kc[NOCl]2
10. Calculate Kp for the reaction 2NOCl(g)
2.1  10-2.
A.
B.
C.
D.
E.
2NO(g) + Cl2(g) at 400C if Kc at 400C for this reaction is
2.1  10-2
1.7  10-3
0.70
1.2
3.8  10-4
11. On analysis, an equilibrium mixture for the reaction 2H2S(g)
2H2(g) + S2(g) was found to contain
1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the equilibrium constant, Kc, for this
reaction.
A.
B.
C.
D.
E.
1.6
3.2
12.8
0.64
0.8
12. 2.50 mol NOCl was placed in a 2.50 L reaction vessel at 400ºC. After equilibrium was established, it was
found that 28% of the NOCl had dissociated according to the equation 2NOCl(g)
2NO(g) + Cl2(g).
Calculate the equilibrium constant, Kc, for the reaction.
A.
B.
C.
D.
E.
0.021
0.039
0.169
26
47
13. 1.25 moles of NOCl were placed in a 2.50 L reaction chamber at 427ºC. After equilibrium was reached,
1.10 moles of NOCl remained. Calculate the equilibrium constant, Kc, for the reaction 2NOCl(g)
2NO(g) + Cl2(g).
A.
B.
C.
D.
E.
3.0  10-4
1.8  103
1.4  10-3
5.6  10-4
4.1  10-3
14. The reaction A(g) + 2B(g)
C(g) was allowed to come to equilibrium. The initial amounts of
reactants placed into a 5.00 L vessel were 1.0 mol A and 1.8 mol B. After the reaction reached
equilibrium, 1.0 mol of B was found. Calculate Kc for this reaction.
A.
B.
C.
D.
E.
0.060
5.1
17
19
25
15. The brown gas NO2 and the colorless gas N2O4 exist in equilibrium, 2NO2
N2O4. In an experiment,
0.625 mole of N2O4 was introduced into a 5.00 L vessel and was allowed to decompose until equilibrium
was reached. The concentration of N2O4 at equilibrium was 0.0750 M. Calculate Kc for the reaction.
A.
B.
C.
D.
E.
7.5
0.125
0.0750
0.10
0.050
16. Calculate Kc for the reaction 2HI(g)
H2(g) + I2(g) given that the concentrations of each species at
equilibrium are as follows:
[HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27 mol/L.
A.
B.
C.
D.
E.
5.25
0.22
4.5
0.19
1.6  102
17. Phosgene, COCl2, a poisonous gas, decomposes according to the equation
COCl2(g)
A.
B.
C.
D.
E.
CO(g) + Cl2(g). Calculate Kp for this reaction if Kc = 0.083 at 900ºC.
0.125
8.0
6.1
0.16
0.083
18. Kp for the reaction of SO2(g) with O2 to produce SO3(g) is 3  1024 . Calculate Kc for this equilibrium at
25ºC. (The relevant reaction is 2SO2(g) + O2(g)
A.
B.
C.
D.
E.
3  1024
5  1021
2  1020
5  1022
7  1025
2SO3(g).)
19. If one starts with pure NO2(g) at a pressure of 0.500 atm, the total pressure inside the reaction vessel when
2NO2(g)
2NO(g) + O2(g) reaches equilibrium is 0.674 atm. Calculate the equilibrium partial
pressure of NO2.
A.
B.
C.
D.
E.
0.152 atm
0.174 atm
0.200 atm
0.326 atm
The total pressure cannot be calculated because Kp is not given.
20. Equilibrium is established for the reaction 2X(s) + Y(g)
2Z(g) at 500K, Kc = 100.
Determine the concentration of Z in equilibrium with 0.2 mol X and 0.50 M Y at 500K.
A.
B.
C.
D.
E.
3.2 M
3.5 M
4.5 M
7.1 M
none of these
21. At 250ºC, the equilibrium constant Kp for the reaction PCl5(g)
PCl3(g) + Cl2(g) is 1.80. Sufficient
PCl5 is put into a reaction vessel to give an initial pressure of 2.74 atm at 250ºC. Calculate the pressure of
PCl5 after the system has reached equilibrium.
A.
B.
C.
D.
E.
1.50 atm
1.24 atm
4.24 atm
0.94 atm
1.12 atm
22. At 35ºC, the equilibrium constant for the reaction 2NOCl(g)
2NO(g) + Cl2(g) is
-5
Kc = 1.6  10 . An equilibrium mixture was found to have the following concentrations of Cl2 and NOCl:
[Cl2] = 1.2  10-2 M; [NOCl] = 2.8  10-1 M. Calculate the concentration of NO(g) at equilibrium.
A.
B.
C.
D.
E.
1.0  10-4 M
1.0  10-2 M
2.8  10-1 M
2.4  10-2 M
1.6  10-3 M
23. For the reaction SO2(g) + NO2(g)
SO3(g) + NO(g), the equilibrium constant is 18.0 at 1,200ºC. If 1.0
mole of SO2 and 2.0 moles of NO2 are placed in a 20. L container, what concentration of SO3 will be
present at equilibrium?
A.
B.
C.
D.
E.
0.48 mol/L
0.11 mol/L
0.95 mol/L
2.22 mol/L
18 mol/L
24. Consider the reaction N2(g) + O2(g)
2NO(g), for which Kc = 0.10 at 2,000ºC. Starting with initial
concentrations of 0.040 M of N2 and 0.040 M of O2, determine the equilibrium concentration of NO.
A.
B.
C.
D.
E.
5.4  10-3 M
0.0096 M
0.011 M
0.080 M
0.10 M
25. Hydrogen iodide decomposes according to the equation 2HI(g)
H2(g) + I2(g), for which Kc = 0.0156
at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC. Calculate the concentration of
HI at equilibrium.
A.
B.
C.
D.
E.
0.138 M
0.220 M
0.550 M
0.275 M
0.0275 M
26. Hydrogen iodide decomposes according to the equation 2HI(g)
H2(g) + I2(g), for which Kc = 0.0156
at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC. Calculate the concentration of
H2 at equilibrium.
A.
B.
C.
D.
E.
0.275 M
0.138 M
0.0275 M
0.0550 M
0.220 M
27. At 400ºC, Kc = 64 for the equilibrium H2(g) + I2(g)
2HI(g). If 3.00 mol H2 and 3.00 mol I2 are
introduced into an empty 4.0 L vessel, find the equilibrium concentration of HI at 400ºC.
A.
B.
C.
D.
E.
0.15 M
1.2 M
2.4 M
4.8 M
5.8 M
28. Sodium carbonate, Na2CO3(s), can be prepared by heating sodium bicarbonate, NaHCO3(s).
2NaHCO3(s)
Na2CO3(s) + CO2(g) + H2O(g) Kp = 0.23 at 100ºC
If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, what
will the total gas pressure be?
A.
B.
C.
D.
E.
0.46 atm
0.96 atm
0.23 atm
0.48 atm
0.11 atm
29. At 340 K, Kp = 69 for the reaction H2(g) + I2(g)
2HI(g). 50.0 g of HI is injected into an evacuated
5.00-L rigid cylinder at 340 K. What is the total pressure inside the cylinder when the system comes to
equilibrium?
A.
B.
C.
D.
E.
2.60 atm
1.76 atm
0.424 atm
2.18 atm
10.9 atm
30. 15.00 g of solid ammonium hydrogen sulfide is introduced into a 500.-mL flask at 25C, the flask is
sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this
flask if Kp = 0.108 at 25C for NH4HS(s)
A.
B.
C.
D.
E.
NH3(g) + H2S (g)?
0.657 atm
1.25 atm
0.329 atm
14.4 atm
2.50 atm
31. For the nitrogen fixation reaction 3H2(g) + N2(g)
2NH3(g), Kc = 6.0  10-2 at 500C. If 0.250 M H2
and 0.050 M NH3 are present at equilibrium, what is the equilibrium concentration of N2?
A.
B.
C.
D.
E.
0.750 M
2.7 M
0.250 M
0.025 M
1.85 M
32. Consider the following reactions and their associated equilibrium constants:
For the reaction A + 2B
A.
B.
C.
D.
E.
Kc = K1 + K2
Kc = K1/K2
Kc = K1 - K2
Kc = (K1)(K2)
Kc = K2/K1
D + E, having equilibrium constant Kc,
33. Consider the following equilibria:
Calculate the equilibrium constant for the reaction
SO2(g) + NO3(g)
A.
B.
C.
D.
E.
SO3(g) + NO2(g).
78
1.3  10-2
1.6  10-4
3.2  10-10
6.1  103
34. At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium constant Kc = 4.3  106, and the
following concentrations are present: [SO2] = 0.10 M; [SO3] = 10. M; [O2] = 0.10 M.
Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is written), left to
right or right to left, will the reaction proceed to reach equilibrium?
A.
B.
C.
D.
Yes, the mixture is at equilibrium.
No, left to right
No, right to left
There is not enough information to be able to predict the direction.
35. At 700 K, the reaction 2SO2(g) + O2(g)
2SO3(g) has the equilibrium constant Kc = 4.3  106, and the
following concentrations are present: [SO2] = 0.010 M; [SO3] = 10.M; [O2] = 0.010 M.
Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is written), left to
right or right to left, will the reaction proceed to reach equilibrium?
A.
B.
C.
D.
Yes, the mixture is at equilibrium.
No, left to right
No, right to left
There is not enough information to be able to predict the direction.
36. For the reaction H2(g) + I2(g)
2HI(g), Kc = 50.2 at 445ºC. If [H2] = [I2] = [HI] = 1.75  10-3 M at
445ºC, which one of these statements is true?
A.
B.
C.
D.
E.
The system is at equilibrium, thus no concentration changes will occur.
The concentrations of HI and I2 will increase as the system approaches equilibrium.
The concentration of HI will increase as the system approaches equilibrium.
The concentrations of H2 and HI will fall as the system moves toward equilibrium.
The concentrations of H2 and I2 will increase as the system approaches equilibrium.
37. For the reaction PCl3(g) + Cl2(g)
PCl5(g) at a particular temperature, Kc = 24.3. Suppose a system at
that temperature is prepared with [PCl3] = 0.10 M, [Cl2] = 0.15 M, and [PCl5] = 0.60 M. Which of these
statements is true?
A.
B.
C.
D.
The reaction is at equilibrium.
The reaction will proceed in the direction of forming more PCl5 until equilibrium is reached.
The reaction will proceed in the direction of forming more PCl3 and Cl2 until equilibrium is reached.
None of these statements is true.
38. For the following reaction at equilibrium, which choice gives a change that will shift the position of
equilibrium to favor formation of more products?
2NOBr(g)
A.
B.
C.
D.
E.
2NO(g) + Br2(g), Hºrxn = 30 kJ/mol
Increase the total pressure by decreasing the volume.
Add more NO.
Remove Br2.
Lower the temperature.
Remove NOBr selectively.
39. For the following reaction at equilibrium, which one of the changes below would cause the equilibrium to
shift to the left?
2NOBr(g)
A.
B.
C.
D.
E.
2NO(g) + Br2(g), Hºrxn = 30 kJ/mol
Increase the container volume.
Remove some NO.
Remove some Br2 .
Add more NOBr.
Decrease the temperature.
40. For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the
Br2 concentration to decrease?
2NOBr(g)
A.
B.
C.
D.
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Increase the temperature.
Remove some NO.
Add more NOBr.
Compress the gas mixture into a smaller volume.
41. For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the
Br2 concentration to increase?
2NOBr(g)
A.
B.
C.
D.
2NO(g) + Br2(g), Hºrxn= 30 kJ/mol
Lower the temperature.
Remove some NO.
Remove some NOBr.
Compress the gas mixture into a smaller volume.
42. For the equilibrium reaction 2SO2(g) + O2(g)
2SO3(g), Hºrxn = -198 kJ/mol. Which one of these
factors would cause the equilibrium constant to increase?
A.
B.
C.
D.
E.
Decrease the temperature.
Add SO2 gas.
Remove O2 gas.
Add a catalyst.
none of these
43. The reaction 2SO3(g)
A.
B.
C.
D.
E.
2SO2(g) + O2(g) is endothermic. If the temperature is increased,
more SO3 will be produced.
Kc will decrease.
no change will occur in Kc .
Kc will increase.
the pressure will decrease.
44. For the reaction at equilibrium 2SO3
temperature, the equilibrium will
A.
B.
C.
D.
2SO2 + O2 (Hºrxn= 198 kJ/mol), if we increase the reaction
shift to the right.
shift to the left.
not shift.
The question cannot be answered because the equilibrium constant is not given.
45. Which of these situations will result if some CH4(g) is removed from the reaction
CO(g) + 3H2(g)
A.
B.
C.
D.
E.
CH4(g) + H2O(g) at equilibrium?
H2O will be consumed.
More CH4 and H2O will be produced.
Kp will decrease.
More CO will be produced.
No change will occur.
46. For the common allotropes of carbon (graphite and diamond), C(gr)
C(dia) with equilibrium
constant K = 0.32. The molar volumes of graphite and diamond are, respectively, 5.30 cm3/mol and 3.42
cm3/mol; Hf of diamond is 1.90 kJ/mol. These data suggest that the formation of diamond is favored at
A.
B.
C.
D.
low temperatures and low pressures.
high temperatures and low pressures.
low temperatures and high pressures.
high temperatures and high pressures.
47. In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on
the reaction mixture?
A.
CO(g) + H2O(g)
CO2(g) + H2(g)
B.
2NO(g) + Cl2(g)
2NOCl(g)
C.
2SO3(g)
2SO2(g) + O2(g)
D.
PCl5(g)
PCl3(g) + Cl2(g)
48. Consider this gas phase equilibrium system:
PCl5(g)
PCl3(g) + Cl2(g) Hºrxn = +87.8 kJ/mol.
Which of these statements is false?
A.
B.
C.
D.
E.
Increasing the system volume shifts the equilibrium to the right.
Increasing the temperature shifts the equilibrium to the right.
A catalyst speeds up the approach to equilibrium and shifts the position of equilibrium to the right.
Decreasing the total pressure of the system shifts the equilibrium to the right.
Increasing the temperature causes the equilibrium constant to increase.
49. The reaction 2NO(g)
N2(g) + O2(g) is exothermic, Hºrxn = -180 kJ/mol.
Which one of these statements is true?
A.
B.
C.
D.
Kp at 1,000 K is less than Kp at 2,000 K.
Kp at 1,000 K is larger than Kp at 2,000 K.
The Kp's at 1000 K and 2000 K are the same.
Kp depends on total pressure as well as temperature.
50. Consider this reaction at equilibrium:
2SO3(g), Hºrxn = -198 kJ/mol
2SO2(g) + O2(g)
If the volume of the system is compressed at constant temperature, what change will occur in the position
of the equilibrium?
A.
B.
C.
D.
a shift to produce more SO2
a shift to produce more O2
no change
a shift to produce more SO3
51. Consider this reaction at equilibrium at a total pressure P1:
2SO2(g) + O2(g)
2SO3(g)
Suppose the volume of this system is compressed to one-half its initial volume and then equilibrium is
reestablished. The new equilibrium total pressure will be
A.
B.
C.
D.
E.
twice P1.
three times P1.
3.5 P1.
less than twice P1.
unchanged.
52. For the reaction 2NOCl(g)
2NO(g) + Cl2(g), Kc = 8.0 at a certain temperature.
What concentration of NOCl must be put into an empty 4.00 L reaction vessel in order that the equilibrium
concentration of NOCl be 1.00 M?
A.
B.
C.
D.
E.
1.26 M
2.25 M
2.50 M
3.52 M
11.0 M
53. The equilibrium constants (expressed in atm) for the chemical reaction
N2(g) + O2(g)
2NO(g) are Kp = 1.1  10-3 and 3.6  10-3 at 2,200 K and 2,500 K, respectively.
Which one of these statements is true?
A.
B.
C.
D.
E.
The reaction is exothermic, Hº < 0.
The partial pressure of NO(g) is less at 2,200 K than at 2,500 K.
Kp is less than Kc by a factor of (RT).
The total pressure at 2,200 K is the same as at 2,500 K.
Higher total pressure shifts the equilibrium to the left.
54. When the substances in the equation below are at equilibrium, at pressure P and temperature T, the
equilibrium can be shifted to favor the products by
CuO(s) + H2(g)
A.
B.
C.
D.
E.
H2O(g) + Cu(s) Hºrxn = -2.0 kJ/mol
increasing the pressure by means of a moving piston at constant T.
increasing the pressure by adding an inert gas such as nitrogen.
decreasing the temperature.
allowing some gases to escape at constant P and T.
adding a catalyst.
55. 50.0 g of N2O4 is introduced into an evacuated 2.00 L vessel and allowed to come to equilibrium with its
decomposition product, N2O4(g)
2NO2(g). For this reaction Kc = 0.133. Once the system has reached
equilibrium, 5.00 g of NO2 is injected into the vessel, and the system is allowed to equilibrate once again.
Calculate the mass of NO2 in the final equilibrium mixture.
A.
B.
C.
D.
E.
17.8 g
12.4 g
14.7 g
19.7 g
15.5 g
56. 50.0 g of N2O4 is introduced into an evacuated 2.00 L vessel and allowed to come to equilibrium with its
decomposition product, N2O4(g)
2NO2(g). For this reaction Kc = 0.133. Once the system has reached
equilibrium, 5.00 g of NO2 is injected into the vessel, and the system is allowed to equilibrate once again.
Calculate the mass of N2O4 in the final equilibrium mixture.
A.
B.
C.
D.
E.
39.5 g
35.3 g
30.3 g
25.2 g
43.7 g
57. 75.0 g of PCl5(g) is introduced into an evacuated 3.00 L vessel and allowed to reach equilibrium at 250ºC.
PCl5(g)
PCl3(g) + Cl2(g)
If Kp = 1.80 for this reaction, what is the total pressure inside the vessel at equilibrium?
A.
B.
C.
D.
E.
2.88 atm
2.27 atm
4.54 atm
7.42 atm
9.69 atm
58. 75.0 g of PCl5(g) is introduced into a 3.00 L vessel containing 10.0 g of Cl2(g), and the system is allowed
to reach equilibrium at 250ºC.
PCl5(g)
PCl3(g) + Cl2(g)
If Kp = 1.80 for this reaction, what is the total pressure inside the vessel at equilibrium?
A.
B.
C.
D.
E.
6.83 atm
8.85 atm
5.38 atm
3.47 atm
7.42 atm
59. 25.0 g of HI(g) is injected into a 4.00 L reaction vessel that contains 20.0 g of I2(g). When the system
comes to equilibrium at 400ºC, what will be the total pressure inside the reaction vessel?
2HI(g)
A.
B.
C.
D.
E.
2.70 atm
13.0 atm
2.43 atm
0.815 atm
3.79 atm
H2(g) + I2(g),
Kc = 0.0156 at 400ºC
60. Solid ammonium hydrogen sulfide is introduced into a 2.00-L flask, and the flask is sealed. If this solid
decomposes according to the equation
NH4HS(s)
NH3(g) + H2S(g), Kp = 0.108 at 25C,
what is the minimum mass of ammonium hydrogen sulfide that must be present in the flask initially if
equilibrium is to be established at 25C?
A.
B.
C.
D.
E.
0.917 g
1.37 g
2.74 g
0.581 g
0.452 g
61. When the reaction 2H2S(g)
2H2(g) + S2(g) is carried out at 1065C, Kp = 0.012. Starting with pure
H2S at 1065, what must the initial pressure of H2S be if the equilibrated mixture at this temperature is to
contain 0.250 atm of H2(g)?
A.
B.
C.
D.
E.
1.06 atm
1.86 atm
0.94 atm
0.90 atm
1.52 atm
62. If the reaction 2H2S(g)
2H2(g) + S2(g) is carried out at 1065C, Kp = 0.0120. Starting from pure H2S
introduced into an evacuated vessel at 1065C, what will the total pressure in the vessel be at equilibrium
if the equilibrated mixture contains 0.300 atm of H2(g)?
A.
B.
C.
D.
E.
1.06 atm
1.36 atm
2.39 atm
4.20 atm
1.51 atm
63. A quantity of liquid methanol, CH3OH, is introduced into a rigid 3.00-L vessel, the vessel is sealed, and
the temperature is raised to 500K. At this temperature, the methanol vaporizes and decomposes according
to the reaction
CH3OH(g)
CO(g) + 2 H2(g), Kc= 6.90 10-2.
If the concentration of H2 in the equilibrium mixture is 0.426 M, what mass of methanol was initially
introduced into the vessel?
A.
B.
C.
D.
E.
147 g
74.3 g
33.9 g
49.0 g
24.8 g
64. Describe why addition of a catalyst does not affect the equilibrium constant for a reaction.
65. Consider the reaction N2(g) + 3H2(g)
2NH3(g). If hydrogen gas is added to this system at
equilibrium, which direction will the reaction shift?
66. Consider the reaction N2(g) + 3H2(g)
2NH3(g). If nitrogen is added to the system at equilibrium,
what will happen to the ammonia concentration?
67. Consider the reaction N2(g) + 3H2(g)
2NH3(g). If nitrogen is removed from the system at
equilibrium, what will happen to the hydrogen (H2) concentration?
68. Consider the reaction N2(g) + 3H2(g)
2NH3(g). The production of ammonia is an endothermic
reaction. Will heating the equilibrium system increase or decrease the amount of ammonia produced?
69. Consider the reaction N2(g) + 3H2(g)
shift?
2NH3(g). If we use a catalyst, which way will the reaction
70. 5.00 mol of ammonia are introduced into a 5.00 L reactor vessel in which it partially dissociates at high
temperatures.
2NH3(g)
3H2(g) + N2(g)
At equilibrium at a particular temperature, 1.00 mole of ammonia remains. Calculate Kc for the reaction.
71. 4.2 mol of oxygen and 4.0 mol of NO are introduced to an evacuated 0.50 L reaction vessel. At a specific
temperature, the equilibrium 2NO(g) + O2(g)
for the reaction at this temperature?
2NO2(g) is reached when [NO] = 1.6 M. Calculate Kc
72. 4.21 moles of S2Cl4 are introduced into a 2.0 L vessel.
S2Cl4(g)
2SCl2(g)
At equilibrium, 1.25 moles of S2Cl4 are found to remain in the container. Calculate Kc for this reaction.
73. The data below refer to the following reaction:
Find the concentration of Br2 when the system reaches equilibrium.
74. The data below refer to the following reaction:
Find the concentration of NOBr when the system reaches equilibrium.
75. The data below refer to the following reaction:
Calculate Kc.
76. Consider the chemical reaction 2NH3(g)
N2(g) + 3H2(g). The equilibrium is to be established in a 1.0
L container at 1,000 K, where Kc = 4.0  10-2. Initially, 1,220 moles of NH3(g) are present.
Estimate the equilibrium concentration of H2(g).
77. Consider the chemical reaction 2NH3(g)
N2(g) + 3H2(g). The equilibrium is to be established in a 1.0
L container at 1,000 K, where Kc = 4.0  10-2. Initially, 1,220 moles of NH3(g) are present.
Estimate the equilibrium concentration of N2(g).
78. Consider the chemical reaction 2NH3(g)
N2(g) + 3H2(g). The equilibrium is to be established in a 1.0
-2
L container at 1,000 K, where Kc = 4.0  10 . Initially, 1,220 moles of NH3(g) are present.
Calculate Kp for the reaction.
79. Hydrogen iodide decomposes according to the equation:
2HI(g)
H2(g) + I2(g), Kc = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of H2 equilibrium.
80. Hydrogen iodide decomposes according to the equation:
2HI(g)
H2(g) + I2(g), Kc = 0.0156 at 400ºC
A 0.660 mol sample of HI was injected into a 2.00 L reaction vessel held at 400ºC.
Calculate the concentration of HI at equilibrium.
81. What conditions are used in the Haber process to enhance the yield of ammonia? Explain why each
condition affects the yield in terms of the Le Châtelier principle.
82. The dissociation of solid silver chloride in water to produce silver ions and chloride ions has an
equilibrium constant of 1.8 x10-18. Based on the magnitude of the equilibrium constant, is silver chloride
very soluble in water? Why?
83. Consider the equilibrium equation C(s) + H2O(g) + 2296 J
CO(g) + H2(g).What will happen to the
concentration of carbon monoxide if the temperature of this system is raised?
84. Consider the equilibrium equation C(s) + H2O(g) + 2296 J
CO(g) + H2(g). If additional gaseous
water is added to this reaction mixture, what will happen to the temperature of the mixture?
85. Consider the equilibrium equation C(s) + H2O(g) + 2296 J
mass of carbon if we add water to the system?
CO(g) + H2(g).What will happen to the
86. Consider the equilibrium equation C(s) + H2O(g) + 2296 J
reaction shift if the pressure on the system is increased?
CO(g) + H2(g).Which way will the
87. Ethanol and acetic acid react to form ethyl acetate and water according to the equation
C2H5OH + CH3COOH
CH3COOC2H5 + H2O
When two moles each of ethanol and acetic acid are allowed to react at 100ºC in a sealed tube, equilibrium
is established when two-thirds of a mole of each of the reactants remains. Calculate the equilibrium
constant for this reaction.
88. 5.00 mol each of acetic acid and ethanol are allowed to react in a 1.00 L sealed container at 100ºC until
equilibrium is established. How many moles of the ester and water are produced in this reaction? The
equilibrium constant is 4.00 for the reaction
C2H5OH + CH3COOH
CH3COOC2H5 + H2O.
89. 5.00 mol each of acetic acid and ethanol are allowed to react in a 1.00 L sealed container at 100ºC until
equilibrium is established. How many moles of ethanol and acid remain following equilibration? The
equilibrium constant is 4.00 for the reaction,
C2H5OH + CH3COOH
CH3COOC2H5 + H2O.
90. What is the correct equilibrium constant expression for this reaction?
2HI(g)
H2(g) + I2(g)
91. Consider the following equilibrium,
4NH3 + 3O2
2 N2 + 6H2O + 1531 kJ
State whether the concentration of each of the reactants would increase, decrease, or remain constant
when the temperature is increased.
92. Consider the following equilibrium,
4NH3 + 3O2
2 N2 + 6H2O + 1531 kJ
State whether the concentration of each of the products would increase, decrease, or remain constant
when the temperature is increased.
93. Consider the following equilibrium,
4NH3 + 3O2
2 N2 + 6H2O + 1531 kJ
State whether the concentration of each of the reactants would increase, decrease, or remain constant
following the addition of 2 mol of ammonia to the system.
94. Consider the following equilibrium,
4NH3 + 3O2
2 N2 + 6H2O + 1531 kJ
State whether the concentration of each of the reaction products would increase, decrease, or remain
constant following the addition of 2 mol of ammonia to the system.
95. Kc for the reaction CO2(g) + H2(g)
H2O(g) + CO(g) is 1.6 at about 990ºC. Calculate the number of
moles of carbon dioxide in the final equilibrium system obtained by initially adding 1.00 mol of H2, 2.00
mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00 L reactor at 990ºC.
96. Kc for the reaction CO2(g) + H2(g)
H2O(g) + CO(g) is 1.6 at about 990ºC. Calculate the number of
moles of hydrogen gas in the final equilibrium system obtained by initially adding 1.00 mol of H2, 2.00
mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00 L reactor at 990ºC.
97. Kc for the reaction CO2(g) + H2(g)
H2O(g) + CO(g) is 1.6 at about 990ºC. Calculate the number of
moles of water in the final equilibrium system obtained by initially adding 1.00 mol of H2, 2.00 mol of
CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00 L reactor at 990ºC.
98. Kc for the reaction CO2(g) + H2(g)
H2O(g) + CO(g) is 1.6 at about 990ºC. Calculate the number of
moles of carbon monoxide in the final equilibrium system obtained by initially adding 1.00 mol of H2,
2.00 mol of CO2, 0.750 mol of H2O, and 1.00 mol of CO to a 5.00 L reactor at 990ºC.
99. Two moles of PCl5 are placed in a 5.0 L container. Dissociation takes place according to the equation PCl5
(g)
PCl3(g) + Cl2(g). At equilibrium, 0.40 mol of Cl2 are present. Calculate the equilibrium constant
(Kc) for this reaction under the conditions of this experiment.
100. The equilibrium constant expression for the reaction
CuO(s) + H2(g)
Cu(s) + H2O(g) is Kc = [H2]/[H2O].
True False
101. When the reaction 2O3(g)
3O2(g), for which Kp = 3.0  1026 at 773ºC, is at equilibrium, the mixture
will contain very little O2 as compared to O3.
True False
102. If the system 3H2(g) + N2(g)
2NH3(g) is at equilibrium and more N2 is added, a net reaction that
consumes some of the added N2 will occur until a new equilibrium is reached.
True False
103. Equilibrium constants are known for the following reactions:
Thus, for the reaction S(s) + O2(g)
True False
SO2(g), Kc = 4.4  1020.
104. For the reaction H2(g) + I2(g)
True False
2HI(g), Kp = Kc.
Chapter 14 Chemical Equilibrium Key
1.C
2.B
3.C
4.C
5.D
6.A
7.E
8.C
9.E
10.D
11.B
12.A
13.D
14.C
15.A
16.B
17.B
18.E
19.A
20.D
21.B
22.B
23.A
24.C
25.B
26.C
Page 1
27.B
28.B
29.D
30.C
31.B
32.D
33.A
34.B
35.C
36.C
37.C
38.C
39.E
40.D
41.B
42.A
43.D
44.A
45.B
46.D
47.B
48.C
49.B
50.D
51.D
52.D
53.B
54.C
55.E
56.A
57.D
Page 2
58.B
59.E
60.B
61.A
62.E
63.B
64.A catalyst affects both the forward and reverse rate of the reaction. Therefore, the equilibrium constant is not affected.
65.The reaction will shift toward the products.
66.[NH3] will increase.
67.[H2] will increase.
68.The amount of NH3 produced will increase.
69.Addition of a catalyst will have no effect on the position of the equilibrium.
70. Kc = 17.3
71. Kc = 3.1
72. Kc = 14.0
73. 4.75 M
74. 1.5 M
75. 0.12
76.20 M
77.6.8 M
78.270
79. 0.033 M
80. 0.264 M
81.High pressure, low temperature, use of a catalyst. Pressure is kept high because high pressure concentrates the reactants to a
greater extent than it does the products. Temperature is kept low because the reaction is exothermic, and use of a catalyst
facilitates the reaction progress.
82.Kc here will be [Ag+(aq)][Cl-(aq)]. If Keq is very small, then the concentrations of the dissolved ions must also be small,
implying that AgCl is not very soluble.
83.It will increase.
84.The temperature will decrease.
85.The mass of carbon will decrease.
86.toward the reactants
Page 3
87. 4
88. 1.67 moles each of acid and ethanol
89. 3.33 moles each of ester and water
90. Kc = [H2][I2]/[HI]2
91. increase
92. decrease
93. decrease
94. increase
95.1.6 mol
96.0.62 mol
97.1.1 mol
98.1.4 mol
99.0.020
100.FALSE
101.FALSE
102.TRUE
103.TRUE
104.TRUE
Page 4