A)
–55.6 kJ/mol
B)
–164.0 kJ/mol
C)
55.6 kJ/mol
D)
164.0 kJ/mol
E)
98.6 kJ/mol
52. Consider the following hypothetical reaction at 310 K. Standard free energies of formation
are given in parentheses.
B C G° = –20.7 kJ/mol
(?) (176.4 kJ/mol)
Calculate the standard free energy of formation of compound B.
A)
155.7 kJ/mol
B)
–197.1 kJ/mol
C)
–155.7 kJ/mol
D)
197.1 kJ/mol
E)
none of these
53. Determine G° for the following reaction:
CH4(g) + 2O2(g) CO2(g) + 2H2O(l)
Substance
Gf° (kJ/mol)
CH4(g)
–50.72
O2(g)
0
CO2(g)
–394.4
H2O(l)
–237.4
A)
–581.1 kJ
B)
–818.5 kJ
C)
131.1 kJ
D)
–682.5 kJ
E)
–919.9 kJ
54. Which of the following is correct for the condensation of gaseous methane at –166°C? The
normal boiling point of methane is –161°C.
A)
H < 0, S > 0, and G > 0.
B)
H < 0, S < 0, and G < 0.
C)
H > 0, S < 0, and G < 0.
D)
H = 0, S = 0, and G < 0.
E)
H > 0, S > 0, and G > 0.
55. If a process is both endothermic and spontaneous, then
A)
H = 0.
B)
G > 0.
C)
S > 0.
D)
U < 0.
E)
H < 0.
56. For a reversible phase change at constant temperature and pressure,
A)
G = 0.
B)
U = 0.
C)
w = 0.
D)
H = 0.
E)
q = 0.
57. For a reaction system that is at equilibrium, which of the following must always be true?
A)
H = 0
B)
S = 0
C)
G = 0
D)
q = 0
E)
U = 0
Test Bank General Chemistry, 10th edition 18
58. An ideal fuel for the control jet of a space vehicle should decompose with
A)
G = 0 and H = 0.
B)
G < 0 and H < 0.
C)
G > 0 and H > 0.
D)
G < 0 and H > 0.
E)
G > 0 and H < 0.
59. For a certain process, at 300. K, G = –44.0 kJ and H = –7.0 kJ. If the process is carried
out reversibly, what is the amount of useful work that can be performed?
A)
–7.0 kJ
B)
–51.0 kJ
C)
–37.0 kJ
D)
37.0 kJ
E)
–44.0 kJ
60. Which of the following is true for the reaction NH3(l) NH3(g) at –33°C and 1 atm
pressure? (The normal boiling point for NH3 is –33°C.)
A)
H = TS
B)
H = 0
C)
H = nRT
D)
S = 0
E)
H = PV
61. Consider the following reaction:
CaO(s) + CO2(g) → CaCO3(s); G° = –130.9 kJ at 298 K
At what partial pressure of CO2(g) will the reaction no longer be spontaneous at 298 K? (R
= 0.0821 L · atm/(K · mol) = 8.31 J/(K · mol))
A)
1.59 108 atm
B)
1.00 atm
C)
6.28 10–9 atm
D)
8.77 1022 atm
E)
1.14 10–23 atm
62. What is the change in free energy at 298 K when 12.0 mL of 0.344 M calcium chloride is
combined with 73.7 mL of 0.245 M sodium carbonate? (R = 8.31 J/(K · mol))
Ca2+(aq) + CO32–(aq) → CaCO3(s)
Substance
G°f (kJ/mol) at 298 K
Ca2+(aq)
–553.5
CO32–(aq)
–527.9
CaCO3(s)
–1128.8
A)
–36.0 kJ
B)
–2.20 103 kJ
C)
–41.3 kJ
D)
–47.4 kJ
E)
9.16 103 kJ
63. Based on the following data, what is the standard Gibbs free energy of formation of the
sulfate ion at 298 K? (R = 8.31 J/(K · mol))
CaSO4(s) Ca2+(aq) + SO42–(aq); Ksp = 2.4 10–5
G°f (kJ/mol) at 298 K
–553.5
–1322.0
A)
–768.5 kJ/mol
B)
–1849.2 kJ/mol
C)
–1875.5 kJ/mol
D)
–742.2 kJ/mol
E)
794.8 kJ/mol
64. Given the following, determine K at 298K for the reaction,
AgBr(s) → Ag+(aq) +Br−(aq)
Substance
G°f (kJ/mol) at 298 K
Br−(aq)
–104.0
Ag+(aq)

AgBr(s)
–96.9
A)
5.3 10−13
B)
5.2 104
C)
1.9 1012
D)
1.9 10−5
E)
1.8 10−49
65. For a reaction, if G° = 0, then
A)
S° = 0.
B)
K = 0.
C)
H° = 0.
D)
K = 1.
E)
G = 0.
66. For a reaction that has an equilibrium constant of 7 10–3, which of the following
statements must be true?
A)
S° is positive.
B)
G° is positive.
C)
G° is negative.
D)
H° is negative.
E)
H° is positive.
67. A certain reaction is found to be product favored. Which of the following is a correct
description of the reaction?
A)
G° < 0, K > 1
B)
G° > 0, K < 1
C)
G° > 0, K > 1
D)
G° < 0, K < 1
E)
G° = 0, K > 1
68. The standard free energy of formation of nitric oxide, NO, at 1000. K (roughly the
temperature in an automobile engine during ignition) is 78.0 kJ/mol. Calculate the
equilibrium constant for the reaction
2NO(g)
at 1000. K. (R = 8.31 J/(K · mol))
A)
0.95
B)
7.0 10–9
C)
1.6 105
D)
–15
E)
8.4 10–5
69. Consider the following hypothetical reaction (at 316.8 K). Standard free energies, in kJ/mol,
are given in parentheses.
A
B
+
C
G° = ?
(–32.2)
(207.8)
(–237.0)
What is the value of the equilibrium constant for the reaction at 316.8 K?
A)
0.42
B)
1.0
C)
273
D)
6.5 104
E)
0.32
70. Consider the following reaction:
3C(s) + 3H2(g) → C3H6(g); H° = 20.41 kJ; S° = –131.6 J/K at 298 K
What is the equilibrium constant at 298 K for this reaction?
A)
3.5 10–11
B)
1.0
C)
1.3 10–7
D)
2.8 1010
E)
2.6 10–4
71. Water gas, a commercial fuel, is made by the reaction of hot coke carbon with steam:
When equilibrium is established at 805°C, the concentrations of CO, H2, and H2O are
4.00 10–2, 4.00 10–2, and 1.00 10–2 mol/L, respectively. Calculate the value of G° for
this reaction at 805°C.
A)
53.7 kJ
B)
12.3 kJ
C)
16.4 kJ
D)
–12.4 kJ
E)
none of these
72. Consider the following reaction:
2AgCl(s) → 2Ag(s) + Cl2(g); H° = 127.1 kJ; S° = 115.7 J/K at 298 K
Suppose 41.0 g of silver(I) chloride is placed in a 70.0 L vessel at 298 K. What is the
equilibrium partial pressure of chlorine gas? (R = 0.0821 L · atm/(K · mol) = 8.31 J/(K ·
mol))
A)
0.050 atm
B)
5.1 10–23 atm
C)
0.95 atm
D)
0.10 atm
E)
5.7 10–17 atm
73. A 0.0997 M solution of a particular monoprotic weak acid, HA, has a pH of 6.00 at 298 K.
What is G° for the following equilibrium?
HA(aq) + H2O(l) H3O+(aq) + A–(aq)
A)
28.5 kJ
B)
34.2 kJ
C)
620 kJ
D)
5.71 kJ
E)
62.7 kJ
74. A 0.0228 M solution of a particular weak base, B, has a pH of 9.11 at 298 K. What is G°
for the following equilibrium?
B(aq) + H2O(l) BH+(aq) + OH–(aq)
A)
27.9 kJ
B)
51.9 kJ
C)
9.36 kJ
D)
46.4 kJ
E)
94.5 kJ
75. What is G° at 298 K for the following equilibrium?
Ag+(aq) + 2NH3(aq) Ag(NH3)2+(aq); Kf = 1.7 107 at 298 K
A)
–41 kJ
B)
41 kJ
C)
–18 kJ
D)
0
E)
18 kJ
Test Bank General Chemistry, 10th edition 24
76. What is G° at 500.0 K for the following reaction?
Sr(s) + H2O(g) → SrO(s) + H2(g)
Substance
H°f (kJ/mol) at 298 K
S° (J/(mol · K)) at 298 K
Sr(s)
0
52.3
H2O(g)
–241.8
188.7
SrO(s)
–634.9
54.4
H2(g)
0
130.6
A)
365.1 kJ
B)
–365.1 kJ
C)
376.4 kJ
D)
–376.4 kJ
E)
–421.1 kJ
77. For the reaction 2SO2(g) + O2(g) → 2SO3(g), H° and S° are both negative at 298 K, and
the process is spontaneous at 298 K. Which of the following statements must also be true?
A)
The change in entropy is the driving force of the reaction.
B)
G is positive for the reaction at 298 K.
C)
The direction of the reaction may be reversed at high temperatures.
D)
G is temperature independent.
E)
At high temperature, H becomes positive.
78. For the reaction 4Ag(s) + O2(g) → 2Ag2O(s), H° = –61.14 kJ and S° = –132 J/K at 25°C.
Which of the following statements is true? Assume that H° and S° are essentially
temperature independent.
A)
The change in entropy is the driving force at low temperatures.
B)
The reaction will be spontaneous at high temperatures, and the reverse reaction
will be spontaneous at low temperatures.
C)
The reaction will not be spontaneous at any temperature.
D)
The reaction will be spontaneous at low temperatures, and the reverse reaction will
be spontaneous at high temperatures.
E)
The reaction will be spontaneous at all temperatures.
Test Bank General Chemistry, 10th edition 25
79. The following reaction is spontaneous at all temperatures:
CaC2(s) + 2H2O(l) → Ca(OH)2(s) + C2H2(g)
Which of the following statements is true?
A)
H is negative and S is positive.
B)
H is negative and S is negative.
C)
H is positive and S is negative.
D)
H is positive and S is positive.
E)
G is positive at all temperatures.
80. The reaction Br2(g) → 2Br(g) is spontaneous only at temperatures in excess of 1600°C. We
can conclude that
A)
H is + and S is + for the reaction.
B)
H is – and S is + for the reaction.
C)
G is + for all temperatures.
D)
H is – and S is – for the reaction.
E)
H is + and S is – for the reaction.
81. A certain reaction has negative values for both H and S. Therefore, the reaction
A)
can be spontaneous if the temperature is low enough.
B)
cannot be spontaneous at any temperature.
C)
must be spontaneous at all temperatures.
D)
can be spontaneous if the temperature is high enough.
E)
has a positive free energy at any temperature.
Test Bank General Chemistry, 10th edition 26
82. The reaction CaO(s) + SO3(g) → CaSO4(s) is nonspontaneous at 2200 K, whereas it is
spontaneous at room temperature. Which of the following statements is false?
A)
The change in enthalpy is the main driving force of the reaction.
B)
Both H and S are negative for the reaction.
C)
G is negative at room temperature.
D)
The change in entropy is the main driving force of the reaction.
E)
G becomes zero at a temperature between 300 and 2200 K.
83. For the reaction CaCO3(s) → CaO(s) + O2(g) at 1 atm pressure, the values of H and S are
both positive, and the process is spontaneous at high temperatures. Which of the following
statements about this reaction is true?
A)
The change in entropy is the driving force for the reaction.
B)
The process is exothermic at high temperatures and endothermic at room
temperature.
C)
The reverse reaction is endothermic.
D)
The reverse reaction is nonspontaneous at room temperature.
E)
G at room temperature is negative.
84. For the reaction SrSO3(s) → SrO(s) + SO2(g), which is spontaneous only at high
temperatures, one would predict that
A)
H is negative and S is negative at room temperature.
B)
H is positive and S is positive at room temperature.
C)
H is positive and S is negative at room temperature.
D)
G is positive at high temperatures.
E)
H is negative and S is positive at room temperature.
Test Bank General Chemistry, 10th edition 27
85. Under standard-state conditions, a reaction with H° < 0 and S° > 0 is
A)
not spontaneous at low temperatures but spontaneous at high temperatures.
B)
at equilibrium.
C)
spontaneous at any temperature.
D)
spontaneous at low temperatures but not at high temperatures.
E)
not spontaneous at any temperature.
86. Consider the following reaction, which is spontaneous at room temperature.
NH3(g) + BF3(g) → H3NBF3(s)
One would predict that
A)
G is negative at all temperatures.
B)
H is positive and S is negative for the reaction.
C)
H is negative and S is positive for the reaction.
D)
H is positive and S is positive for the reaction.
E)
H is negative and S is negative for the reaction.
87. Which of the following statements is true concerning the reaction below?
CH4(g) + N2(g) → HCN(g) + NH3(g); H° = 164.1 kJ; G° = 159.1 kJ at 298 K
A)
It is nonspontaneous at all temperatures.
B)
It is spontaneous at relatively low temperatures only.
C)
It is spontaneous at all temperatures.
D)
It is at equilibrium at 298 K.
E)
It is spontaneous at relatively high temperatures only.
88. Which of the following statements is true for the following reaction?
NH4HS(s) → NH3(g) + H2S(g); H° = 93 kJ
A)
The reaction is not spontaneous at any temperature.
B)
The reaction is spontaneous only at relatively high temperatures.
C)
The reaction is at equilibrium under standard-state conditions.
D)
The reaction is spontaneous at all temperatures.
E)
The reaction is spontaneous only at relatively low temperatures.
89. The reaction C(s) + CO2(g) → 2CO(g) is spontaneous only at temperatures in excess of
1100 K. We can conclude that
A)
G° is negative for all temperatures.
B)
H° is negative and S° is negative.
C)
H° is positive and S° is positive.
D)
H° is negative and S° is positive.
E)
H° is positive and S° is negative.
90. Sublimation is an example of a process for which
A)
H is positive and S is negative at all temperatures.
B)
H is negative and S is positive at all temperatures.
C)
H, S, and G are negative at all temperatures.
D)
H and S are positive at all temperatures.
E)
H, S, and G are positive at all temperatures.
Test Bank General Chemistry, 10th edition 29
91. Condensation is a process for which
A)
G is negative at high temperature but positive at low temperature.
B)
H, S, and G are positive at all temperatures.
C)
G is positive when condensation occurs spontaneously.
D)
H and S are positive at all temperatures.
E)
H and S are negative at all temperatures.
92. Consider the following reaction, which is spontaneous at room temperature.
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
One would predict that
A)
H is positive and S is positive for the reaction.
B)
G is positive at all temperatures.
C)
H is negative and S is negative for the reaction.
D)
H is positive and S is negative for the reaction.
E)
H is negative and S is positive for the reaction.
93. Which of the following statements is true concerning the reaction below?
C(s, graphite) → C(s, diamond)
Substance
H°f (kJ/mol) at 298 K
S° (J/(mol · K)) at 298 K
C(s, graphite)
0
5.740
C(s, diamond)
1.897
2.377
A)
Under standard-state conditions, the reaction is spontaneous at all temperatures.
B)
Under standard-state conditions, the reaction is spontaneous only at temperatures
above 564 K.
C)
Under standard-state conditions, the reaction is spontaneous only at temperatures
below 564 K.
D)
Under standard-state conditions, the reaction is at equilibrium at 298 K.
E)
Under standard-state conditions, the reaction is not spontaneous at any
temperature.
94. For the reaction G°700K = –13.457 kJ. What is Kp for this
reaction at 700. K?
A)
1.00
B)
1.54
C)
10.1
D)
2.31
E)
none of these
95. Consider the following reaction:
2C(s) + 3H2(g) → C2H6(g); H° = –84.68 kJ; S° = –173.8 J/K at 298 K
What is the equilibrium constant at 400.0 K for this reaction?
A)
1.0 10–2
B)
2.0 104
C)
1.0
D)
9.5 101
E)
8.6 10–10