Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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| 1. | If
the reaction A + B  C has an equilibrium constant greater than one, which
of the following statements is correct? a. | The reaction is not spontaneous. | b. | The forward rate
of reaction is fast. | c. | The backward rate of reaction is
slow. | d. | The reaction is product favored. | e. | All of the above
statements are correct. | | |
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| 2. | If a
chemical reaction has a positive change in entropy, S, then a. | the disorder of
the system increases. | b. | the reaction is exothermic. | c. | heat goes from
the system into the surroundings. | d. | the Gibbs free energy is negative. | e. | the reaction is
spontaneous. | | |
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| 3. | Thermodynamics can be used to determine all of the following EXCEPT a. | the direction in
which a reaction is spontaneous. | b. | the extent to which a reaction
occurs. | c. | the rate of reaction. | d. | the temperature
at which a reaction is spontaneous. | e. | the enthalpy change of a reaction. | | |
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| 4. | Which
of the following involves a decrease in entropy? a. | the sublimation of carbon dioxide | b. | the dissolution
of NaCl in water | c. | the decomposition of N2O4(g) to
NO2(g) | d. | the evaporation of ethanol | e. | the freezing of
liquid water into ice | | |
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| 5. | 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 entropy of the universe is continually
increasing. | d. | the enthalpy of reaction is the difference between product and
reactant enthalpies. | e. | the Gibbs free energy is a function of both enthalpy and
entropy. | | |
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| 6. | Of
the following product-favored processes, which are endothermic?
1. the combustion of methane to produce water and carbon
dioxide
2. the expansion of an ideal gas
3. the melting
of ice at temperatures greater than 0ºC. a. | 1 only | b. | 2
only | c. | 3
only | d. | 1 and
2 | e. | 2 and
3 | | |
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| 7. | All
of the following statements concerning entropy are true EXCEPT a. | entropy is zero
for elements under standard conditions. | b. | entropy is a state function. | c. | a positive
change in entropy denotes a change toward greater disorder. | d. | entropy values
are greater than or equal to zero. | e. | the entropy a substance in the gas phase is greater than the
solid phase. | | |
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| 8. | All
of the following processes lead to an increase in entropy EXCEPT a. | increasing the
temperature of a gas. | b. | freezing a liquid. | c. | evaporating a
liquid. | d. | forming mixtures from pure
substances. | e. | chemical reactions that increase the number of moles of
gas. | | |
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| 9. | Predict the signs of DH and DS for the evaporation of water at 35ºC. a. | DH > 0 and DS > 0 | b. | DH > 0 and DS < 0 | c. | DH < 0 and DS > 0 | d. | DH < 0 and DS < 0 | e. | Not enough
information is provided to answer this question. | | |
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| 10. | Predict the signs of DH, DS, and DG for the combustion of hydrogen gas at 25ºC.
2 H2(g) + O2(g) ® 2
H2O(ª)
a. | DH < 0, DS < 0, DG < 0 | b. | DH < 0, DS > 0, DG < 0 | c. | DH < 0, DS > 0, DG < 0 | d. | DH > 0, DS < 0, DG < 0 | e. | DH > 0, DS < 0, DG > 0 | | |
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| 11. | Predict the signs of DH, DS, and DG for the melting of ice at 50ºC. a. | DH < 0, DS < 0, DG < 0 | b. | DH < 0, DS > 0, DG < 0 | c. | DH < 0, DS > 0, DG < 0 | d. | DH > 0, DS < 0, DG < 0 | e. | DH > 0, DS > 0, DG < 0 | | |
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| 12. | If
DG < 0
for a reaction at all temperatures, then DS is ________ and DH is ________. a. | positive, positive | b. | positive,
negative | c. | zero, positive | d. | negative,
positive | e. | negative, zero | | |
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| 13. | The
dissolution of ammonium nitrate occurs spontaneously in water. As NH4NO3
dissolves, the temperature of the water decreases. What are the signs of H, S, and
G for this process? a. | DH < 0, DS < 0, DG < 0 | b. | DH < 0, DS > 0, DG < 0 | c. | DH < 0, DS > 0, DG < 0 | d. | DH > 0, DS > 0, DG < 0 | e. | DH > 0, DS < 0, DG > 0 | | |
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| 14. | Diluting concentrated sulfuric acid with water can be dangerous. The temperature of
the solution can increase rapidly. What are the signs of H, S, and G for this
process? a. | DH < 0,
DS < 0,
DG <
0 | b. | DH < 0,
DS > 0,
DG <
0 | c. | DH < 0,
DS > 0,
DG <
0 | d. | DH > 0,
DS > 0,
DG <
0 | e. | DH > 0,
DS < 0,
DG >
0 | | |
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| 15. | Above
what temperature would you expect a reaction to become spontaneous if DH = +322
kJ and DS = +531
J/K? a. | 171
K | b. | 209
K | c. | 606
K | d. | The reaction
will be spontaneous at any temperature. | e. | The reaction will NOT be spontaneous at any
temperature. | | |
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| 16. | For a
reaction, DH = +265
kJ and DS =
+271.3 J/K. At what temperature will DG = 0.00? a. | 6.30 K | b. | 102
K | c. | 359
K | d. | 719
K | e. | 977
K | | |
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| 17. | If a
process is endothermic and spontaneous, which of the following must be true? a. | DG > 0 and DH < 0 | b. | DG < 0 and DH < 0 | c. | DG < 0 and DS > 0 | d. | DH < 0 and DS > 0 | e. | DH > 0 and DS < 0 | | |
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| 18. | If
DGº< 0, then a. | K >1 | b. | K =
0 | c. | K <
1 | d. | K =
1 | e. | K <
0 | | |
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| 19. | Which
of the following is not a General observation of the entropies of a substance: a. | Entropy
increases from solid to liquid to gas | b. | Entrophy of complex molecules are higher than entropies of
simplier molecules | c. | Entrophy increases as temperature
increases | d. | Entropies usually increase when mixtures are
made | e. | Entrophy
increases in a reaction in which the number of moles of gas decrease | | |
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