Exam 20: Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

A) 129.3 kJ
B) 133.6 kJ
C) 196.0 kJ
D) 199.8 kJ
E) 229.6 kJ

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A) It is non-spontaneous at all T.
B) It is spontaneous at high T.
C) It is spontaneous at low T.
D) It is spontaneous at all T.
E) None of these conclusions is correct.

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T = 463 K. The calculation is ...

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A) ( $\Delta$ H $\degree$ > 0, $\Delta$ S $\degree$ > 0)
B) ( $\Delta$ H $\degree$ > 0, $\Delta$ S $\degree$ < 0)
C) ( $\Delta$ H $\degree$ < 0, $\Delta$ S $\degree$ > 0)
D) ( $\Delta$ H $\degree$ < 0, $\Delta$ S $\degree$ < 0)
E) None of these choices is correct.

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A) ( $\Delta$ S $\degree$ $\approx$ 0)
B) ( $\Delta$ S $\degree$ < 0)
C) ( $\Delta$ S $\degree$ > 0)
D) ( $\Delta$ S $\degree$ = $\Delta$ H $\degree$ /T)
E) More information is needed to make a reasonable prediction.

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A) -18.2 J/K*mol
B) 18.2 J/K*mol
C) 290.1 J/K*mol
D) 355.4 J/K*mol
E) 450.6 J/K*mol

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A microstate is a specific, quantized st...

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A) ( $\Delta$ SF $\degree$$\approx$ 0)
B) ( $\Delta$ S $\degree$ < 0)
C) ( $\Delta$ S $\degree$ > 0)
D) ( $\Delta$ S $\degree$ = $\Delta$ H $\degree$ /T)
E) More information is needed to make a reasonable prediction.

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A) melting
B) heating a gas
C) vaporization
D) condensation
E) sublimation

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A) 1 mole He(g) ; 1 mole Kr(g)
B) 1 mole O₂(g) ; 2 mole O(g)
C) 1 mole CH₄(g) ; 1 mole C₂H₆(g)
D) 1 mole Xe(g) at 1 atmosphere; 1 mole Xe(g) at 0.5 atmosphere
E) 20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people

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All spontaneous processes are ...

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A) ( $\Delta$ S $\degree$ > 0, $\Delta$ H $\degree$ > 0)
B) ( $\Delta$ S $\degree$ > 0, $\Delta$ H $\degree$ < 0)
C) ( $\Delta$ S $\degree$ < 0, $\Delta$ H $\degree$ < 0)
D) ( $\Delta$ S $\degree$ < 0, $\Delta$ H $\degree$ > 0)
E) It is not possible for a reaction to be spontaneous at all temperatures.

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A) ( $\Delta$ H $\degree$ _f = 0 for Al(s) at 298 K)
B) ( $\Delta$ G $\degree$ _f = 0 for H₂(g) at 298 K)
C) (S $\degree$ = 51.446 J/(mol·K) for Na(s) at 298 K)
D) (q _sys < 0 for H₂O(l) $\rightarrow$ H₂O(s) at 0 $\degree$ C)
E) None of these choices is correct.

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A) ( $\Delta$ H > 0)
B) ( $\Delta$ H < 0)
C) ( $\Delta$ S_sys > 0)
D) ( $\Delta$ S_surr > $\Delta$ S_sys)
E) ( $\Delta$ S > $\Delta$ H/T)

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A) -293.4 kJ
B) 293.4 kJ
C) -102.8 kJ
D) 102.8 kJ
E) None of these choices is correct.

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A) S $\degree$ _pentane > S $\degree$ _{1,3-pentadiene}
B) S $\degree$ _pentane < S $\degree$ _{1,3-pentadiene}
C) S $\degree$ _pentane $\approx$ S $\degree$ _{1,3-pentadiene}
D) S $\degree$ _pentane  S $\degree$ _{1,3-pentadiene} + 2*
E) More information is needed to make reasonable predictions.

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A) ( $\Delta$ G $\degree$ = 2.19 kJ; forever
B) ( $\Delta$ G $\degree$ = -1.90 kJ; not forever)
C) ( $\Delta$ G $\degree$ = -2.90 kJ; not forever)
D) ( $\Delta$ G $\degree$ = 1.90 kJ; forever)
E) ( $\Delta$ G $\degree$ = < -1000 kJ; not forever)

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