Question 1

Which of the following is consistent with an exothermic reaction that is spontaneous at all temperatures

Accepted Answer

A) ($\Delta$H) > 0, $\Delta$S  0, $\Delta$S > 0, $\Delta$G  0, $\Delta$G  0, $\Delta$S  0 
A) ($\Delta$H) > 0, $\Delta$S  0, $\Delta$S > 0, $\Delta$G  0, $\Delta$G  0, $\Delta$S  0

Question 2

For the reaction 3H2(g) + N2(g) $\leftrightharpoons$ 2NH3(g), Kc = 9.0 at 350$\circ$C. What is the value of $\Delta$G at this temperature when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor

Accepted Answer

A)  -33.2 kJ/mol 
B)  -35.2 kJ/mol 
C)  -37.2 kJ/mol 
D)  -39.2 kJ/mol 
E)  None of the above 
A)  -33.2 kJ/mol 
B)  -35.2 kJ/mol 
C)  -37.2 kJ/mol 
D)  -39.2 kJ/mol 
E)  None of the above

Question 3

For the reaction H2O2(g) $\rarr$ H2O(g) + 1/2O2(g), $\Delta$H$\circ$ = -106 kJ/mol and $\Delta$S$\circ$ = 58 J/K·mol at 25$\circ$C. Calculate $\Delta$G$\circ$ for this reaction at this temperature.

Accepted Answer

A)  -423 kJ/mol 
B)  -323 kJ/mol 
C)  -223 kJ/mol 
D)  -123 kJ/mol 
E)  None of the above 
A)  -423 kJ/mol 
B)  -323 kJ/mol 
C)  -223 kJ/mol 
D)  -123 kJ/mol 
E)  None of the above

Question 4

Arrange the following substances in the order of increasing entropy at 25$\circ$C.HF(g), NaF(s), SiF4(g), SiH4(g), Al(s) 
 lowest $\rarr$ highest

Accepted Answer

A)  SiF4(g) 4(g) 4(g) 4(g) 
C)  Al(s) 4(g) 4(g) 
D)  Al(s) 4(g) 4(g) 
E)  NaF(s) 4(g) 4(g) 
A)  SiF4(g) 4(g) 4(g) 4(g) 
C)  Al(s) 4(g) 4(g) 
D)  Al(s) 4(g) 4(g) 
E)  NaF(s) 4(g) 4(g)

Question 5

Determine $\Delta$S$\circ$ for the reaction SO3(g) + H2O(l) $\rarr$ H2SO4(l). $\begin{array}{lc}
&\mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol})\\hline
\mathrm{SO}_{3} & 256.2 \
\mathrm{H}_{2} \mathrm{O} & 69.9 \
\mathrm{H}_{2} \mathrm{SO}_{4} & 156.9
\end{array}$

Accepted Answer

A)  169.2 J/K·mol 
B)  1343.2 J/K·mol 
C)  -169.2 J/K·mol 
D)  -29.4 J/K·mol 
E)  29.4 J/K·mol 
A)  169.2 J/K·mol 
B)  1343.2 J/K·mol 
C)  -169.2 J/K·mol 
D)  -29.4 J/K·mol 
E)  29.4 J/K·mol

Question 6

At 700 K, the equilibrium constant for the reaction CO(g) + H2O(g) $\leftrightharpoons$ CO2(g) + H2(g) is 5.10. What is $\Delta$G$\circ$ for this reaction at this temperature

Accepted Answer

A)  -9.08 kJ/mol 
B)  -9.28 kJ/mol 
C)  -9.48 kJ/mol 
D)  -9.68 kJ/mol 
E)  None of the above 
A)  -9.08 kJ/mol 
B)  -9.28 kJ/mol 
C)  -9.48 kJ/mol 
D)  -9.68 kJ/mol 
E)  None of the above

Question 7

The reaction SiO2(s) + Pb(s) $\rarr$ PbO2(s) + Si(s) is spontaneous.
$\Delta$G$\circ$f (PbO2) = -217 kJ/mol
$\Delta$G$\circ$f (SiO2) = -856 kJ/mol

Accepted Answer

A) True 
 B)False

Question 8

Which of these species would you expect to have the lowest standard entropy (S$\circ$)

Accepted Answer

A)  Br2(l) 
B)  Cl2(g) 
C)  F2(g) 
D)  H2(g) 
E)  I2(s) 
A)  Br2(l) 
B)  Cl2(g) 
C)  F2(g) 
D)  H2(g) 
E)  I2(s)

Question 9

Without reference to a table, arrange these reactions according to increasing $\Delta$S.
1) CH4(g) + H2O(g) $\rarr$ CO(g) + 3H2(g) 
2) C(s) + O2(g) $\rarr$CO2(g)
3) H2O2(l) $\rarr$ H2O(l) + 1/2O2(g)

Accepted Answer

A)  1 < 3 < 2 
B)  2 < 3 < 1 
C)  2 < 1 < 3 
D)  3 < 2 < 1 
E)  3 < 1 < 2 
A)  1 < 3 < 2 
B)  2 < 3 < 1 
C)  2 < 1 < 3 
D)  3 < 2 < 1 
E)  3 < 1 < 2

Question 10

HI has a normal boiling point of -35.4$\circ$C, and its $\Delta$Hvap is 21.16 kJ/mol. Calculate the molar entropy of vaporization ($\Delta$Svap).

Accepted Answer

A)  598 J/K·mol 
B)  68.6 J/K·mol 
C)  75.2 J/K·mol 
D)  0.068 J/K·mol 
E)  89.0 J/K·mol 
A)  598 J/K·mol 
B)  68.6 J/K·mol 
C)  75.2 J/K·mol 
D)  0.068 J/K·mol 
E)  89.0 J/K·mol

Question 11

Given the following data, estimate the boiling point of bromine, Br2, assuming that $\Delta$S$\circ$ and $\Delta$H$\circ$ are temperature-independent. $\begin{array}{|l|c|c|}
\hline & \Delta \mathrm{H}^\circ_{\mathrm{f}}(\mathrm{~kJ} / \mathrm{mol}) & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{Br}_{2}(g) & 30.91 & 245.3 \
\hline \mathrm{Br}_{2}(l) & 0 & 152.3 \
\hline
\end{array}$

Accepted Answer

A)  59.2$\circ$C 
B)  61.2$\circ$C 
C)  63.2$\circ$C 
D)  65.2$\circ$C 
E)  None of the above 
A)  59.2$\circ$C 
B)  61.2$\circ$C 
C)  63.2$\circ$C 
D)  65.2$\circ$C 
E)  None of the above

Question 12

For the reaction 2 SO2(g) + O2(g) $\rarr$ 2 SO3(g), if initially P(SO2) = 1.2 atm, P(O2) = 1.8 atm, and P(SO3) = 2.1 atm, calculate $\Delta$G for this reaction at 25$\circ$C. The following data is valid at 25$\circ$C: $\begin{array}{|l|l|}
\hline & \Delta \mathrm{G}_{\mathrm{f}}{ }^{\circ}(\mathrm{kJ} / \mathrm{mol}) \
\hline \mathrm{SO}_{2} & -300.4 \
\hline \mathrm{SO}_{3} & -370.4 \
\hline
\end{array}$

Accepted Answer

A)  -140.0 kJ/mol 
B)  -137.6 kJ/mol 
C)  -138.7 kJ/mol 
D)  1,174.7 kJ/mol 
E)  -141.3 kJ/mol 
A)  -140.0 kJ/mol 
B)  -137.6 kJ/mol 
C)  -138.7 kJ/mol 
D)  1,174.7 kJ/mol 
E)  -141.3 kJ/mol

Question 13

Which of these species would you expect to have the highest standard entropy (S$\circ$)

Accepted Answer

A)  CH4(g) 
B)  C2H2(g) 
C)  C2H4(g) 
D)  C2H6(g) 
E)  C3H8(g) 
A)  CH4(g) 
B)  C2H2(g) 
C)  C2H4(g) 
D)  C2H6(g) 
E)  C3H8(g)

Question 14

For the reaction CuS(s) + H2(g) $\leftrightharpoons$ H2S(g) + Cu(s), 
$\Delta$G$\circ$f (CuS) = -53.6 kJ/mol
$\Delta$G$\circ$f (H2S) = -33.6 kJ/mol
$\Delta$H$\circ$f (CuS) = -53.1 kJ/mol
$\Delta$H$\circ$f (H2S) = -20.6 kJ/mol
Calculate $\Delta$G at 798 K and 1 atm pressure (assume $\Delta$S$\circ$ and $\Delta$H$\circ$ do not change with temperature).

Accepted Answer

A)  -1.02 kJ/mol 
B)  -1.22 kJ/mol 
C)  -1.42 kJ/mol 
D)  -1.62 kJ/mol 
E)  None of the above 
A)  -1.02 kJ/mol 
B)  -1.22 kJ/mol 
C)  -1.42 kJ/mol 
D)  -1.62 kJ/mol 
E)  None of the above

Question 15

For the reaction 2C(graphite) + H2(g) $\rarr$C2H2(g), $\Delta$G$\circ$= +209.2 kJ/mol at 25$\circ$C. If P(H2) = 100. atm, and P(C2H2) = 0.10 atm, calculate $\Delta$G for this reaction.

Accepted Answer

A)  +207.8 kJ/mol 
B)  +226.3 kJ/mol 
C)  +192.1 kJ/mol 
D)  +17.3 kJ/mol 
E)  -16.9 kJ/mol 
A)  +207.8 kJ/mol 
B)  +226.3 kJ/mol 
C)  +192.1 kJ/mol 
D)  +17.3 kJ/mol 
E)  -16.9 kJ/mol

Question 16

Predict the signs (-, +, or 0) of $\Delta$H and $\Delta$S, in that order, for the expansion of an ideal gas into a vacuum.

Accepted Answer

A)  0, - 
B)  0, + 
C)  +, + 
D)  -, - 
E)  None of the above 
A)  0, - 
B)  0, + 
C)  +, + 
D)  -, - 
E)  None of the above

Question 17

Which of the following processes would be accompanied by a decrease in entropy

Accepted Answer

A) H2O(s) $\rarr$H2O(g) 
B) H2O(l) $\rarr$H2O(g) 
C) H2O(s) $\rarr$ H2O(l) 
D) H2O(g) $\rarr$H2O(s) 
E) H2O(l, 50$\circ$
C)  $\rarr$ H2O(l, 75$\circ$
C)  
A) H2O(s) $\rarr$H2O(g) 
B) H2O(l) $\rarr$H2O(g) 
C) H2O(s) $\rarr$ H2O(l) 
D) H2O(g) $\rarr$H2O(s) 
E) H2O(l, 50$\circ$
C)  $\rarr$ H2O(l, 75$\circ$
C)

Question 18

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium nitrate is dissolved in water. $\begin{array}{|l|c|}
\hline & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{NaNO}_{3}(\mathrm{s}) & 116.3 \
\hline \mathrm{Na}^{+}(a q) & 60.25 \
\hline \mathrm{NO}_{3}^{-}(a q) & 146.4 \
\hline
\end{array}$ Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased

Accepted Answer

A)  -90.4 J/K·mol; solubility decreases with increasing temperature 
B)  -90.4 J/K·mol; solubility increases with increasing temperature 
C)  90.4 J/K·mol; solubility decreases with increasing temperature 
D)  90.4 J/K·mol; solubility increases with increasing temperature 
E)  None of the above 
A)  -90.4 J/K·mol; solubility decreases with increasing temperature 
B)  -90.4 J/K·mol; solubility increases with increasing temperature 
C)  90.4 J/K·mol; solubility decreases with increasing temperature 
D)  90.4 J/K·mol; solubility increases with increasing temperature 
E)  None of the above

Question 19

Arrange these compounds in order of increasing standard molar entropy at 25$\circ$C: C3H8(g), C2H4(g), ZnS(s), and H2O(l).

Accepted Answer

A)  ZnS(s) 2O(l) 3H8(g) 2H4(g) 
B)  C2H4(g) 2O(l) 3H8(g) 3H8(g) 2H4(g) 2O(l) 
D)  C3H8(g) 2H4(g) 2O(l) 2O(l) 2H4(g) 3H8(g) 
A)  ZnS(s) 2O(l) 3H8(g) 2H4(g) 
B)  C2H4(g) 2O(l) 3H8(g) 3H8(g) 2H4(g) 2O(l) 
D)  C3H8(g) 2H4(g) 2O(l) 2O(l) 2H4(g) 3H8(g)

Question 20

The process: H2O(l) $\rarr$ H2O(s) expected to be spontaneous at low temperatures only.

Accepted Answer

A) True 
 B)False

Exam 17: Entropy Free Energy and Equilibrium

Which of the following is consistent with an exothermic reaction that is spontaneous at all temperatures

For the reaction 3H2(g) + N2(g) ⇋\leftrightharpoons⇋ 2NH3(g), Kc = 9.0 at 350 ∘\circ∘ C. What is the value of Δ\DeltaΔ G at this temperature when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor

For the reaction H2O2(g) →\rarr→ H2O(g) + 1/2O2(g), Δ\DeltaΔ H ∘\circ∘ = -106 kJ/mol and Δ\DeltaΔ S ∘\circ∘ = 58 J/K·mol at 25 ∘\circ∘ C. Calculate Δ\DeltaΔ G ∘\circ∘ for this reaction at this temperature.

Arrange the following substances in the order of increasing entropy at 25 ∘\circ∘ C.HF(g), NaF(s), SiF4(g), SiH4(g), Al(s) lowest →\rarr→ highest

Determine Δ\DeltaΔ S ∘\circ∘ for the reaction SO3(g) + H2O(l) →\rarr→ H2SO4(l). (/\cdot) 256.2 69.9 156.9

At 700 K, the equilibrium constant for the reaction CO(g) + H2O(g) ⇋\leftrightharpoons⇋ CO2(g) + H2(g) is 5.10. What is Δ\DeltaΔ G ∘\circ∘ for this reaction at this temperature

The reaction SiO2(s) + Pb(s) →\rarr→ PbO2(s) + Si(s) is spontaneous. Δ\DeltaΔ G ∘\circ∘ f (PbO2) = -217 kJ/mol Δ\DeltaΔ G ∘\circ∘ f (SiO2) = -856 kJ/mol

Which of these species would you expect to have the lowest standard entropy (S ∘\circ∘ )

Without reference to a table, arrange these reactions according to increasing Δ\DeltaΔ S. 1) CH4(g) + H2O(g) →\rarr→ CO(g) + 3H2(g) 2) C(s) + O2(g) →\rarr→ CO2(g) 3) H2O2(l) →\rarr→ H2O(l) + 1/2O2(g)

HI has a normal boiling point of -35.4 ∘\circ∘ C, and its Δ\DeltaΔ Hvap is 21.16 kJ/mol. Calculate the molar entropy of vaporization ( Δ\DeltaΔ Svap).

Given the following data, estimate the boiling point of bromine, Br2, assuming that Δ\DeltaΔ S ∘\circ∘ and Δ\DeltaΔ H ∘\circ∘ are temperature-independent. \Delta(/) (/\cdot) (g) 30.91 245.3 (l) 0 152.3

For the reaction 2 SO2(g) + O2(g) →\rarr→ 2 SO3(g), if initially P(SO2) = 1.2 atm, P(O2) = 1.8 atm, and P(SO3) = 2.1 atm, calculate Δ\DeltaΔ G for this reaction at 25 ∘\circ∘ C. The following data is valid at 25 ∘\circ∘ C: \Delta(/) -300.4 -370.4

Which of these species would you expect to have the highest standard entropy (S ∘\circ∘ )

For the reaction 2C(graphite) + H2(g) →\rarr→ C2H2(g), Δ\DeltaΔ G ∘\circ∘ = +209.2 kJ/mol at 25 ∘\circ∘ C. If P(H2) = 100. atm, and P(C2H2) = 0.10 atm, calculate Δ\DeltaΔ G for this reaction.

Predict the signs (-, +, or 0) of Δ\DeltaΔ H and Δ\DeltaΔ S, in that order, for the expansion of an ideal gas into a vacuum.

Which of the following processes would be accompanied by a decrease in entropy

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium nitrate is dissolved in water. (/\cdot) () 116.3 (aq) 60.25 (aq) 146.4 Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased

Arrange these compounds in order of increasing standard molar entropy at 25 ∘\circ∘ C: C3H8(g), C2H4(g), ZnS(s), and H2O(l).

The process: H2O(l) →\rarr→ H2O(s) expected to be spontaneous at low temperatures only.

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For the reaction 3H₂(g) + N₂(g) $\leftrightharpoons$ 2NH₃(g), K_c = 9.0 at 350^$\circ$C. What is the value of $\Delta$ G at this temperature when 1.0 mol NH₃, 5.0 mol N₂, and 5.0 mol H₂ are mixed in a 2.5 L reactor

For the reaction H₂O₂(g) $\rarr$ H₂O(g) + ¹/₂O₂(g), $\Delta$ H^$\circ$ = -106 kJ/mol and $\Delta$ S^$\circ$ = 58 J/K·mol at 25^$\circ$C. Calculate $\Delta$ G^$\circ$ for this reaction at this temperature.

Arrange the following substances in the order of increasing entropy at 25^$\circ$C.HF(g), NaF(s), SiF₄(g), SiH₄(g), Al(s) lowest $\rarr$ highest

Determine $\Delta$ S^$\circ$ for the reaction SO₃(g) + H₂O(l) $\rarr$ H₂SO₄(l). (/\cdot) 256.2 69.9 156.9

At 700 K, the equilibrium constant for the reaction CO(g) + H₂O(g) $\leftrightharpoons$ CO₂(g) + H₂(g) is 5.10. What is $\Delta$ G^$\circ$ for this reaction at this temperature

The reaction SiO₂(s) + Pb(s) $\rarr$ PbO₂(s) + Si(s) is spontaneous. $\Delta$ G^$\circ$_f (PbO₂) = -217 kJ/mol $\Delta$ G^$\circ$_f (SiO₂) = -856 kJ/mol

Which of these species would you expect to have the lowest standard entropy (S^$\circ$)

Without reference to a table, arrange these reactions according to increasing $\Delta$ S. 1) CH₄(g) + H₂O(g) $\rarr$ CO(g) + 3H₂(g) 2) C(s) + O₂(g) $\rarr$ CO₂(g) 3) H₂O₂(l) $\rarr$ H₂O(l) + ¹/₂O₂(g)

HI has a normal boiling point of -35.4^$\circ$C, and its $\Delta$ H_vap is 21.16 kJ/mol. Calculate the molar entropy of vaporization ( $\Delta$ S_vap).

Given the following data, estimate the boiling point of bromine, Br₂, assuming that $\Delta$ S^$\circ$ and $\Delta$ H^$\circ$ are temperature-independent. \Delta(/) (/\cdot) (g) 30.91 245.3 (l) 0 152.3

For the reaction 2 SO₂(g) + O₂(g) $\rarr$ 2 SO₃(g), if initially P(SO₂) = 1.2 atm, P(O₂) = 1.8 atm, and P(SO₃) = 2.1 atm, calculate $\Delta$ G for this reaction at 25^$\circ$C. The following data is valid at 25^$\circ$C: \Delta(/) -300.4 -370.4

Which of these species would you expect to have the highest standard entropy (S^$\circ$)

For the reaction 2C(graphite) + H₂(g) $\rarr$ C₂H₂(g), $\Delta$ G^$\circ$= +209.2 kJ/mol at 25^$\circ$C. If P(H₂) = 100. atm, and P(C₂H₂) = 0.10 atm, calculate $\Delta$ G for this reaction.

Predict the signs (-, +, or 0) of $\Delta$ H and $\Delta$ S, in that order, for the expansion of an ideal gas into a vacuum.

Arrange these compounds in order of increasing standard molar entropy at 25^$\circ$C: C₃H₈(g), C₂H₄(g), ZnS(s), and H₂O(l).

The process: H₂O(l) $\rarr$ H₂O(s) expected to be spontaneous at low temperatures only.