Multiple
Choice
Identify the letter of the choice that best completes the statement or answers the
question.
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1.
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A statement of the second law
of thermodynamics is that a. | spontaneous reactions are always
exothermic. | b. | energy is conserved in a chemical reaction. | c. | the Gibbs free energy is a function of both enthalpy and
entropy. | d. | ΔS = - ΔH for any chemical
reaction. | e. | in a spontaneous process, the entropy of the universe
increases. | | |
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2.
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Which of the following linear
chain alcohols is likely to have the highest standard entropy in the liquid state? a. | CH3OH | b. | CH3CH2OH | c. | CH3CH2CH2OH | d. | CH3CH2CH2CH2OH | e. | CH3CH2CH2CH2CH2OH | | |
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3.
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Which of the following
processes are reversible?
1. | the expansion of an ideal gas into a vacuum | 2. | the melting of ice at 0 °C | 3. | the combustion of carbon to produce carbon
dioxide | | |
a. | 1 only | b. | 2 only | c. | 3 only | d. | 1 and 2 | e. | 2 and 3 | | |
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4.
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Calculate the standard entropy
change for the combustion of methanol at 25 °C.
2 CH3OH(l) + 3
O2(g) → 2 CO2(g) + 4
H2O(g)
Species | S°
(J/K⋅mol) | CH3OH(l) | 127.2 | O2(g) | 205.1 | CO2(g) | 213.7 | H2O(g) | 188.8 | | |
a. | -2052.3 J/K | b. | -312.9 J/K | c. | +70.2 J/K | d. | +312.9 J/K | e. | +2052.3 J/K | | |
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5.
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Calculate 
for the reaction below at 25.0 °C
2 Ca(s) + O2(g) → 2 CaO
given  = -1270.2 kJ and  = -211.9
J/K. a. | -1058.3 kJ | b. | -1207.0 kJ | c. | -1269.5 kJ | d. | -1333.4 kJ | e. | -1482.1 kJ | | |
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6.
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Calculate ΔG° for the reaction below at 125
°C.
C2H5OH(g) + 3 O2(g) → 2 CO2(g) + 3 H2O(g)
Species |  (kJ/mol) |  (J/K·
mol) | C2H5OH(g) | -235.3 | 282.7 | O2(g) | 0 | 205.1 | CO2(g) | -393.5 | 213.7 | H2O(g) | -241.8 | 188.8 | | | |
a. | -366.0 kJ | b. | -1277.1 kJ | c. | -1289.1 kJ | d. | -1315.2 kJ | e. | -3.94 ×
104 kJ | | |
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7.
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Given
that
C(s) + O2(g) →
CO2(g) ΔG° = -394.4 kJ
CO(g) +  O2(g) →
CO2(g) ΔG° = -257.2 kJ
calculate ΔG° for the following reaction.
2 C(s) + O2(g) → 2
CO(g)
a. | -651.6 kJ | b. | -274.4 kJ | c. | -137.2 kJ | d. | +137.2 kJ | e. | +274.4 kJ | | |
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8.
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For a chemical system,
ΔG° and
ΔG are equal when a. | the system is in equilibrium. | b. | the reactants and products are in standard state conditions. | c. | the equilibrium constant, K, equals 0. | d. | the reaction quotient, Q, is less than 1. | e. | the reactants and products are in the gas phase. | | |
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9.
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The standard free energy change
for the formation of N2H4(l) from
elements is +149 kJ/mol at 25 °C. What is the equilibrium constant for
the reaction? (R = 8.314 J/K·mol) a. | 7 ×
10-61 | b. | 8 ×
10-27 | c. | 1 | d. | 1 × 1026 | e. | 1 × 1060 | | |
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10.
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The equilibrium constant for a
reaction at 25 °C is 4.7 × 10-8. What is ΔG°? (R = 8.314
J/K·mol) a. | +1.52 kJ | b. | +3.51 kJ | c. | +6.81 kJ | d. | +18.2 kJ | e. | +41.8 kJ | | |
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