Question 1

Calculate $\Delta$S$\circ$ for the reaction SO2(s) + NO2(g) $\rarr$ SO3(g) + NO(g). $\begin{array}{lc}
&\mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol})\\hline
\mathrm{SO}_{2}(\mathrm{g}) & 248.5 \
\mathrm{SO}_{3}(\mathrm{g}) & 256.2 \
\mathrm{NO}{(g)} & 210.6 \
\mathrm{NO}_{2}(\mathrm{g}) & 240.5
\end{array}$

Accepted Answer

A)  53.6 J/K·mol 
B)  -53.6 J/K·mol 
C)  -22.2 J/K·mol 
D)  474.8 J/K·mol 
E)  -474.8 J/K·mol 
A)  53.6 J/K·mol 
B)  -53.6 J/K·mol 
C)  -22.2 J/K·mol 
D)  474.8 J/K·mol 
E)  -474.8 J/K·mol

Question 2

Predict the signs (-, +, or 0) of $\Delta$H and $\Delta$S, in that order, for the process: H2O(l) $\rarr$H2O(s).

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 3

In the gas phase, methyl isocyanate (CH3NC) isomerizes to acetonitrile (CH3CN), H3C-N$\equiv$C (g) $\leftrightharpoons$ H3C-C$\equiv$N (g)
With $\Delta$H$\circ$ = -89.5 kJ/mol and $\Delta$G$\circ$ = - 73.8 kJ/mol at 25$\circ$C. Find the equilibrium constant for this reaction at 100$\circ$C.

Accepted Answer

A)  1.68 * 10-10 
B)  5.96 * 109 
C)  2.16 * 1010 
D)  4.63 * 10-11 
E)  8.64 * 1012 
A)  1.68 * 10-10 
B)  5.96 * 109 
C)  2.16 * 1010 
D)  4.63 * 10-11 
E)  8.64 * 1012

Question 4

$\Delta$Hvap for ethanol is 38.7 kJ/mol at its boiling point (78$\circ$C). What is $\Delta$Ssurr when 1.00 mole of ethanol is boiled

Accepted Answer

A)  -310 J/K·mol 
B)  -210 J/K·mol 
C)  -110 J/K·mol 
D)  -100 J/K·mol 
E)  None of the above 
A)  -310 J/K·mol 
B)  -210 J/K·mol 
C)  -110 J/K·mol 
D)  -100 J/K·mol 
E)  None of the above

Question 5

Using the thermodynamic data provided below, calculate Ksp for Mg(OH)2(s) at 25$\circ$. $\begin{array}{|l|l|c|}
\hline & \Delta \mathrm{H}^\circ_{\mathrm{f}}(\mathrm{~kJ} / \mathrm{mol}) & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{Mg}^{2+}(a q) & -461.96 & -117.99 \
\hline \mathrm{OH}^-(a q) & -229.94 & -10.5 \
\hline \mathrm{Mg}(\mathrm{OH})_{2}(s) & -924.66 & 63.1 \
\hline
\end{array}$

Accepted Answer

A)  8.50 * 10-12 
B)  8.70 * 10-12 
C)  8.90 * 10-12 
D)  9.10 * 10-12 
E)  None of the above 
A)  8.50 * 10-12 
B)  8.70 * 10-12 
C)  8.90 * 10-12 
D)  9.10 * 10-12 
E)  None of the above

Question 6

In the gas phase, formic acid forms a dimer, 2HCOOH(g) $\leftrightharpoons$ (HCOOH)2(g). For this reaction, $\Delta$H$\circ$ = -60.1 kJ/mol and $\Delta$G$\circ$ = -13.9 kJ/mol at 25$\circ$C. Find the equilibrium constant (Kp) for this reaction at 75 $\circ$C.

Accepted Answer

A)  8960 
B)  273 
C)  0.120 
D)  8.33 
E)  1.12 * 10-4 
A)  8960 
B)  273 
C)  0.120 
D)  8.33 
E)  1.12 * 10-4

Question 7

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. H2O2(g) is stable with respect to dissociation into water vapor and oxygen gas at 25$\circ$C.

Accepted Answer

A) True 
 B)False

Question 8

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium sulfate is dissolved in water. $\begin{array}{|l|c|}
\hline & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{Na}_{2} \mathrm{SO}_{4}(s) & 149.49 \
\hline \mathrm{Na}^{+}(a q) & 60.25 \
\hline \mathrm{SO}_{4}{ }^{2-}(a q) & 17.15 \
\hline
\end{array}$ Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased

Accepted Answer

A)  -11.84 J/K·mol; solubility decreases with increasing temperature 
B)  -11.84 J/K·mol; solubility increases with increasing temperature 
C)  11.84 J/K·mol; solubility decreases with increasing temperature 
D)  11.84 J/K·mol; solubility increases with increasing temperature 
E)  None of the above 
A)  -11.84 J/K·mol; solubility decreases with increasing temperature 
B)  -11.84 J/K·mol; solubility increases with increasing temperature 
C)  11.84 J/K·mol; solubility decreases with increasing temperature 
D)  11.84 J/K·mol; solubility increases with increasing temperature 
E)  None of the above

Question 9

Which of the following is consistent with a spontaneous endothermic reaction

Accepted Answer

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

Question 10

Which of the following is consistent with a reaction that proceeds spontaneously in the forward direction

Accepted Answer

A) ($\Delta$G) > 0, Q $\circ$) = 0, Q = K C) ($\Delta$G) K D) ($\Delta$G$\circ$) > 0, Q = K E) ($\Delta$G) < 0, Q < K A) ($\Delta$G) > 0, Q $\circ$) = 0, Q = K C) ($\Delta$G) K D) ($\Delta$G$\circ$) > 0, Q = K E) ($\Delta$G) < 0, Q < K

Question 11

Ozone (O3) in the atmosphere can react with nitric oxide (NO): O3(g) + NO(g) $\rarr$NO2(g) + O2(g).Calculate the $\Delta$G$\circ$ for this reaction at 25$\circ$C. ($\Delta$H$\circ$ = -199 kJ/mol, $\Delta$S$\circ$ = -4.1 J/K·mol)

Accepted Answer

A)  1020 kJ/mol 
B)  -1.22 * 103 kJ/mol 
C)  2.00 * 103 kJ/mol 
D)  -1.42 * 103 kJ/mol 
E)  -198 kJ/mol 
A)  1020 kJ/mol 
B)  -1.22 * 103 kJ/mol 
C)  2.00 * 103 kJ/mol 
D)  -1.42 * 103 kJ/mol 
E)  -198 kJ/mol

Question 12

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.4Al(s) + 3O2(g) $\rarr$ 2Al2O3(s) Calculate $\Delta$G$\circ$ for this reaction, given that $\Delta$G$\circ$f of aluminum oxide is -1576.4 kJ/mol.

Accepted Answer

A)  -3152.8 kJ/mol 
B)  -1576.4 kJ/mol 
C)  -788.2 kJ/mol 
D)  1576.4 kJ/mol 
E)  3152.8 kJ/mol 
A)  -3152.8 kJ/mol 
B)  -1576.4 kJ/mol 
C)  -788.2 kJ/mol 
D)  1576.4 kJ/mol 
E)  3152.8 kJ/mol

Question 13

The equilibrium constant for the reaction AgBr(s) $\leftrightharpoons$ Ag+(aq) + Br- (aq) is the solubility product constant, Ksp = 7.7 *10-13 at 25$\circ$C. Calculate $\Delta$G for the reaction when [Ag+] = 1.0 * 10-2 M and [Br-] = 1.0 * 10-3 M. Is the reaction spontaneous or nonspontaneous at these concentrations

Accepted Answer

A)  ($\Delta$G) = 69.1 kJ/mol, nonspontaneous 
B)  ($\Delta$G) = -69.1 kJ/mol, spontaneous 
C)  ($\Delta$G) = 97.5 kJ/mol, spontaneous 
D)  ($\Delta$G) = 40.6 kJ/mol, nonspontaneous 
E)  ($\Delta$G) = -97.5 kJ/mol, nonspontaneous 
A)  ($\Delta$G) = 69.1 kJ/mol, nonspontaneous 
B)  ($\Delta$G) = -69.1 kJ/mol, spontaneous 
C)  ($\Delta$G) = 97.5 kJ/mol, spontaneous 
D)  ($\Delta$G) = 40.6 kJ/mol, nonspontaneous 
E)  ($\Delta$G) = -97.5 kJ/mol, nonspontaneous

Question 14

At a given temperature, 1 mole of N2(g) in a 22.4 L container has a higher entropy per mole than 1 mole of N2(g) in a 2.24 L container.

Accepted Answer

A) True 
 B)False

Question 15

The solubility product constant at 25$\circ$C for AgI(s) in water has the value 8.3 * 10-17. Calculate $\Delta$Grxn at 25$\circ$C for the process AgI(s) $\leftrightharpoons$ Ag+(aq) + I- (aq) where [Ag+] = 9.1 * 10-9 and [I-] = 9.1 * 10-9.

Accepted Answer

A)  +4.4 kJ/mol 
B)  +91.7 kJ/mol 
C)  0.0 kJ/mol 
D)  -91.7 kJ/mol 
E)  -4.4 kJ/mol 
A)  +4.4 kJ/mol 
B)  +91.7 kJ/mol 
C)  0.0 kJ/mol 
D)  -91.7 kJ/mol 
E)  -4.4 kJ/mol

Question 16

Which of the following is consistent with a reaction that proceeds spontaneously in the reverse direction (assume all variables are in terms of the forward direction only)

Accepted Answer

A)  ($\Delta$G) > 0, Q $\circ$) = 0, Q = K 
C)  ($\Delta$G)  K 
D)  ($\Delta$G$\circ$) > 0, Q = K 
E)  ($\Delta$G) > 0, Q > K 
A)  ($\Delta$G) > 0, Q $\circ$) = 0, Q = K 
C)  ($\Delta$G)  K 
D)  ($\Delta$G$\circ$) > 0, Q = K 
E)  ($\Delta$G) > 0, Q > K

Question 17

The equilibrium constant at 427$\circ$C for the reaction N2(g) + 3H2(g) $\leftrightharpoons$ 2NH3(g) is Kp = 9.4 * 10-5. Calculate the value of $\Delta$G$\circ$ for the reaction under these conditions.

Accepted Answer

A)  -33 kJ/mol 
B)  -54 kJ/mol 
C)  54 kJ/mol 
D)  33 kJ/mol 
E)  1.3 J/mol 
A)  -33 kJ/mol 
B)  -54 kJ/mol 
C)  54 kJ/mol 
D)  33 kJ/mol 
E)  1.3 J/mol

Question 18

The entropy of any pure substance at 0 K is 0 J/mol.

Accepted Answer

A) True 
 B)False

Question 19

Find the temperature at which Kp = 42.0 for the reaction H2(g) + I2(g) $\leftrightharpoons$ 2HI(g). [Given: at 25$\circ$C, for H2(g), $\Delta$H$\circ$f = 0, S$\circ$ = 131.0 J/mol·K; for I2(g), $\Delta$H$\circ$f = 62.26 kJ/mol, S$\circ$ = 260.6 J/mol·K; for HI(g), $\Delta$H$\circ$f = 25.9 kJ/mol, S$\circ$ = 206.3 J/mol·K; assume that $\Delta$H$\circ$ and $\Delta$S$\circ$ are independent of temperature.]

Accepted Answer

A)  1040 K 
B)  168 K 
C)  539 K 
D)  1400 K 
E)  34,200 K 
A)  1040 K 
B)  168 K 
C)  539 K 
D)  1400 K 
E)  34,200 K

Question 20

At 1500$\circ$C the equilibrium constant for the reaction CO(g) + 2H2(g) $\leftrightharpoons$ CH3OH(g) has the value Kp = 1.4 * 10-7. Calculate $\Delta$G$\circ$ for this reaction at 1500$\circ$C.

Accepted Answer

A)  105 kJ/mol 
B)  1.07 kJ/mol 
C)  -233 kJ/mol 
D)  -105 kJ/mol 
E)  233 kJ/mol 
A)  105 kJ/mol 
B)  1.07 kJ/mol 
C)  -233 kJ/mol 
D)  -105 kJ/mol 
E)  233 kJ/mol

Exam 17: Entropy Free Energy and Equilibrium

Calculate Δ\DeltaΔ S ∘\circ∘ for the reaction SO2(s) + NO2(g) →\rarr→ SO3(g) + NO(g). (/\cdot) () 248.5 () 256.2 (g) 210.6 () 240.5

Predict the signs (-, +, or 0) of Δ\DeltaΔ H and Δ\DeltaΔ S, in that order, for the process: H2O(l) →\rarr→ H2O(s).

Δ\DeltaΔ Hvap for ethanol is 38.7 kJ/mol at its boiling point (78 ∘\circ∘ C). What is Δ\DeltaΔ Ssurr when 1.00 mole of ethanol is boiled

Using the thermodynamic data provided below, calculate Ksp for Mg(OH)2(s) at 25 ∘\circ∘ . \Delta(/) (/\cdot) (aq) -461.96 -117.99 (aq) -229.94 -10.5 ((s) -924.66 63.1

In the gas phase, formic acid forms a dimer, 2HCOOH(g) ⇋\leftrightharpoons⇋ (HCOOH)2(g). For this reaction, Δ\DeltaΔ H ∘\circ∘ = -60.1 kJ/mol and Δ\DeltaΔ G ∘\circ∘ = -13.9 kJ/mol at 25 ∘\circ∘ C. Find the equilibrium constant (Kp) for this reaction at 75 ∘\circ∘ C.

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. H2O2(g) is stable with respect to dissociation into water vapor and oxygen gas at 25 ∘\circ∘ C.

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium sulfate is dissolved in water. (/\cdot) (s) 149.49 (aq) 60.25 (aq) 17.15 Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased

Which of the following is consistent with a spontaneous endothermic reaction

Which of the following is consistent with a reaction that proceeds spontaneously in the forward direction

Ozone (O3) in the atmosphere can react with nitric oxide (NO): O3(g) + NO(g) →\rarr→ NO2(g) + O2(g).Calculate the Δ\DeltaΔ G ∘\circ∘ for this reaction at 25 ∘\circ∘ C. ( Δ\DeltaΔ H ∘\circ∘ = -199 kJ/mol, Δ\DeltaΔ S ∘\circ∘ = -4.1 J/K·mol)

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.4Al(s) + 3O2(g) →\rarr→ 2Al2O3(s) Calculate Δ\DeltaΔ G ∘\circ∘ for this reaction, given that Δ\DeltaΔ G ∘\circ∘ f of aluminum oxide is -1576.4 kJ/mol.

At a given temperature, 1 mole of N2(g) in a 22.4 L container has a higher entropy per mole than 1 mole of N2(g) in a 2.24 L container.

The solubility product constant at 25 ∘\circ∘ C for AgI(s) in water has the value 8.3 * 10-17. Calculate Δ\DeltaΔ Grxn at 25 ∘\circ∘ C for the process AgI(s) ⇋\leftrightharpoons⇋ Ag+(aq) + I- (aq) where [Ag+] = 9.1 * 10-9 and [I-] = 9.1 * 10-9.

Which of the following is consistent with a reaction that proceeds spontaneously in the reverse direction (assume all variables are in terms of the forward direction only)

The equilibrium constant at 427 ∘\circ∘ C for the reaction N2(g) + 3H2(g) ⇋\leftrightharpoons⇋ 2NH3(g) is Kp = 9.4 * 10-5. Calculate the value of Δ\DeltaΔ G ∘\circ∘ for the reaction under these conditions.

The entropy of any pure substance at 0 K is 0 J/mol.

At 1500 ∘\circ∘ C the equilibrium constant for the reaction CO(g) + 2H2(g) ⇋\leftrightharpoons⇋ CH3OH(g) has the value Kp = 1.4 * 10-7. Calculate Δ\DeltaΔ G ∘\circ∘ for this reaction at 1500 ∘\circ∘ C.

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Filters

Calculate $\Delta$ S^$\circ$ for the reaction SO₂(s) + NO₂(g) $\rarr$ SO₃(g) + NO(g). (/\cdot) () 248.5 () 256.2 (g) 210.6 () 240.5

Predict the signs (-, +, or 0) of $\Delta$ H and $\Delta$ S, in that order, for the process: H₂O(l) $\rarr$ H₂O(s).

$\Delta$ H_vap for ethanol is 38.7 kJ/mol at its boiling point (78^$\circ$C). What is $\Delta$ S_surr when 1.00 mole of ethanol is boiled

Using the thermodynamic data provided below, calculate K_sp for Mg(OH)₂(s) at 25^$\circ$. \Delta(/) (/\cdot) (aq) -461.96 -117.99 (aq) -229.94 -10.5 ((s) -924.66 63.1

In the gas phase, formic acid forms a dimer, 2HCOOH(g) $\leftrightharpoons$ (HCOOH)₂(g). For this reaction, $\Delta$ H^$\circ$ = -60.1 kJ/mol and $\Delta$ G^$\circ$ = -13.9 kJ/mol at 25^$\circ$C. Find the equilibrium constant (K_p) for this reaction at 75 ^$\circ$C.

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. H₂O₂(g) is stable with respect to dissociation into water vapor and oxygen gas at 25^$\circ$C.

Ozone (O₃) in the atmosphere can react with nitric oxide (NO): O₃(g) + NO(g) $\rarr$ NO₂(g) + O₂(g).Calculate the $\Delta$ G^$\circ$ for this reaction at 25^$\circ$C. ( $\Delta$ H^$\circ$ = -199 kJ/mol, $\Delta$ S^$\circ$ = -4.1 J/K·mol)

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion.4Al(s) + 3O₂(g) $\rarr$ 2Al₂O₃(s) Calculate $\Delta$ G^$\circ$ for this reaction, given that $\Delta$ G^$\circ$_f of aluminum oxide is -1576.4 kJ/mol.

At a given temperature, 1 mole of N₂(g) in a 22.4 L container has a higher entropy per mole than 1 mole of N₂(g) in a 2.24 L container.

The solubility product constant at 25^$\circ$C for AgI(s) in water has the value 8.3 * 10^-17. Calculate $\Delta$ G_rxn at 25^$\circ$C for the process AgI(s) $\leftrightharpoons$ Ag⁺(aq) + I^- (aq) where [Ag⁺] = 9.1 * 10^-9 and [I^-] = 9.1 * 10^-9.

The equilibrium constant at 427^$\circ$C for the reaction N₂(g) + 3H₂(g) $\leftrightharpoons$ 2NH₃(g) is K_p = 9.4 * 10^-5. Calculate the value of $\Delta$ G^$\circ$ for the reaction under these conditions.

At 1500^$\circ$C the equilibrium constant for the reaction CO(g) + 2H₂(g) $\leftrightharpoons$ CH₃OH(g) has the value K_p = 1.4 * 10^-7. Calculate $\Delta$ G^$\circ$ for this reaction at 1500^$\circ$C.