Question 1

Calculate Kp at 298 K for the reaction SO2(g) + NO2(g) $\leftrightharpoons$ SO3(g) + NO(g). $\begin{array}{lc}
&\Delta \mathrm{G}_{\mathrm{f}}^{\circ}\\hline
\mathrm{SO}_{2}(\mathrm{g}) & -300.4 \mathrm{~kJ} / \mathrm{mol} \
\mathrm{SO}_{3}(\mathrm{g}) & -370.4 \mathrm{~kJ} / \mathrm{mol} \
\mathrm{NO}(\mathrm{g}) & 86.7 \mathrm{~kJ} / \mathrm{mol} \
\mathrm{NO}_{2}(\mathrm{g}) & 51.8 \mathrm{~kJ} / \mathrm{mol}
\end{array}$

Accepted Answer

A)  6.99 * 10-7 
B)  5.71 * 10-8 
C)  14.2 
D)  475 
E)  1.42 * 106 
A)  6.99 * 10-7 
B)  5.71 * 10-8 
C)  14.2 
D)  475 
E)  1.42 * 106

Question 2

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
This reaction proceeds spontaneously at 298 K and 1 atm pressure.

Accepted Answer

A) True 
 B)False

Question 3

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) Using the thermodynamic data provided below, calculate $\Delta$S$\circ$ for this reaction. $\begin{array}{|l|c|}
\hline & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{Al}(s) & 28.3 \
\hline \mathrm{O}_{2}(g) & 205.0 \
\hline \mathrm{Al}_{2} \mathrm{O}_{3}(s) & 50.99 \
\hline
\end{array}$

Accepted Answer

A)  182.3 J/K·mol 
B)  131.5 J/K·mol 
C)  -182.3 J/K·mol 
D)  -626.2 J/K·mol 
E)  -802.9 J/K·mol 
A)  182.3 J/K·mol 
B)  131.5 J/K·mol 
C)  -182.3 J/K·mol 
D)  -626.2 J/K·mol 
E)  -802.9 J/K·mol

Question 4

Find the temperature at which the reaction N2O4(g) $\leftrightharpoons$ 2NO2(g) will be in equilibrium when both gases are present at partial pressures of 1.00 atm. $\begin{array}{lcc}
&\Delta \mathrm{H}^{\circ}{ }_{\mathrm{f}}\left(25^{\circ} \mathrm{C}\right) & \Delta \mathrm{G}^{\circ}_\mathrm{f}\left(25^{\circ} \mathrm{C}\right)\\hline
\mathrm{NO}_{2}(\mathrm{g}) & 33.85 \mathrm{~kJ} / \mathrm{mol} & 51.8 \mathrm{~kJ} / \mathrm{mol} \
\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{g}) & 9.66 \mathrm{~kJ} / \mathrm{mol} & 98.29 \mathrm{~kJ} / \mathrm{mol}
\end{array}$

Accepted Answer

A)  300$\circ$C 
B)  28$\circ$C 
C)  55$\circ$C 
D)  32$\circ$C 
E)  562$\circ$C 
A)  300$\circ$C 
B)  28$\circ$C 
C)  55$\circ$C 
D)  32$\circ$C 
E)  562$\circ$C

Question 5

At a given temperature, Br2(l) has a higher entropy per mole than Br2(g).

Accepted Answer

A) True 
 B)False

Question 6

For the reaction H2(g) + S(s) $\rarr$ H2S(g), $\Delta$H$\circ$ = -20.2 kJ/mol and $\Delta$S$\circ$ = +43.1 J/K·mol. Which of these statements is true

Accepted Answer

A)  The reaction is only spontaneous at low temperatures. 
B)  The reaction is spontaneous at all temperatures. 
C)  ($\Delta$G$\circ$) becomes less favorable as temperature increases. 
D)  The reaction is spontaneous only at high temperatures. 
E)  The reaction is at equilibrium at 25$\circ$C under standard conditions. 
A)  The reaction is only spontaneous at low temperatures. 
B)  The reaction is spontaneous at all temperatures. 
C)  ($\Delta$G$\circ$) becomes less favorable as temperature increases. 
D)  The reaction is spontaneous only at high temperatures. 
E)  The reaction is at equilibrium at 25$\circ$C under standard conditions.

Question 7

Using the thermodynamic data provided below, calculate Ka1 for H2CO3(aq) at 25$\circ$. $\begin{array}{|l|l|c|}
\hline & \Delta \mathrm{H}_{\mathrm{f}}^{\circ}(\mathrm{kJ} / \mathrm{mol}) & \mathrm{S}^{\circ}(\mathrm{J} / \mathrm{K} \cdot \mathrm{~mol}) \
\hline \mathrm{H}^{+}(a q) & 0 & 0 \
\hline \mathrm{H}_{2} \mathrm{CO}_{3}(a q) & -698.7 & 191 \
\hline \mathrm{HCO}_{3}^{-}(a q) & -691.11 & 95.0 \
\hline \mathrm{CO}_{3}^{2-}(a q) & -676.26 & -53.1 \
\hline
\end{array}$

Accepted Answer

A)  5 * 10-5 
B)  5 * 10-6 
C)  5 * 10-7 
D)  5 * 10-8 
E)  None of the above 
A)  5 * 10-5 
B)  5 * 10-6 
C)  5 * 10-7 
D)  5 * 10-8 
E)  None of the above

Question 8

Assuming $\Delta$S$\circ$ and $\Delta$H$\circ$ do not vary with temperature, at what temperature will the reaction shown below become spontaneous
C(s) + H2O(g)$\rarr$H2(g) + CO(s) ($\Delta$S$\circ$ = 133.6 J/K·mol; $\Delta$H$\circ$ = 131.3 kJ/mol)

Accepted Answer

A)  670$\circ$C 
B)  690$\circ$C 
C)  710$\circ$C 
D)  730$\circ$C 
E)  None of the above 
A)  670$\circ$C 
B)  690$\circ$C 
C)  710$\circ$C 
D)  730$\circ$C 
E)  None of the above

Question 9

Predict the signs (-, +, or 0) of $\Delta$H and $\Delta$S, in that order, for the reaction: O2(g) $\rarr$ 2O(g).

Accepted Answer

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

Question 10

Predict the signs (-, +, or 0) of $\Delta$H and $\Delta$S, in that order, for the reaction: 6CO2(g) + 6H2O(g) $\rarr$C6H12O6(g) + 6O2(g).

Accepted Answer

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

Question 11

The element oxygen was prepared by Joseph Priestley in 1774 by heating mercury(II) oxide: HgO(s) $\rarr$ Hg(l) + 1/2O2(g), $\Delta$H$\circ$ = 90.84 kJ/mol.Estimate the temperature at which this reaction will become spontaneous under standard state conditions.S$\circ$(Hg) = 76.02 J/K·mol
S$\circ$(O2) = 205.0 J/K·mol
S$\circ$(HgO) = 70.29 J/K·mol

Accepted Answer

A)  108 K 
B)  430 K 
C)  620 K 
D)  775 K 
E)  840 K 
A)  108 K 
B)  430 K 
C)  620 K 
D)  775 K 
E)  840 K

Question 12

The heat of vaporization of water is 2.27 kJ/g. What is $\Delta$Svap per mole at the normal boiling point

Accepted Answer

A)  170. J/K·mol 
B)  150. J/K·mol 
C)  130. J/K·mol 
D)  110. J/K·mol 
E)  None of the above 
A)  170. J/K·mol 
B)  150. J/K·mol 
C)  130. J/K·mol 
D)  110. J/K·mol 
E)  None of the above

Question 13

For any pure substance, if $\Delta$Hf$\circ$ = 0 and $\Delta$Gf$\circ$ = 0, then S$\circ$ = 0.

Accepted Answer

A) True 
 B)False

Question 14

Determine the equilibrium constant (Kp) at 25$\circ$C for the reaction $\begin{array}{ll}
\begin{array}{l}
\mathrm{CO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) 
\leftrightharpoons 
\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{g}) .
\end{array}\\
\Delta \mathrm{G}^{\circ}=-28.5 \mathrm{~kJ} / \mathrm{mol}
\end{array}$

Accepted Answer

A)  2.9 * 10-60 
B)  1.0* 10-4 
C)  1.2 
D)  1.0 * 105 
E)  3.4 * 1059 
A)  2.9 * 10-60 
B)  1.0* 10-4 
C)  1.2 
D)  1.0 * 105 
E)  3.4 * 1059

Question 15

Which of the following is consistent with a nonspontaneous process in the forward direction

Accepted Answer

A) ($\Delta$Suniv) > 0, $\Delta$G univ > 0 
B) ($\Delta$Suniv)  0, T$\Delta$Suniv univ) > 0, $\Delta$G univ univ) univ univ) > 0, $\Delta$G > 0, T$\Delta$Suniv > 0 
A) ($\Delta$Suniv) > 0, $\Delta$G univ > 0 
B) ($\Delta$Suniv)  0, T$\Delta$Suniv univ) > 0, $\Delta$G univ univ) univ univ) > 0, $\Delta$G > 0, T$\Delta$Suniv > 0

Question 16

The reaction 3H2(g) + N2(g) $\leftrightharpoons$ 2NH3(g),(Kc = 9.0 at 350$\circ$C) proceeds from right to left at 350$\circ$C under standard state conditions.

Accepted Answer

A) True 
 B)False

Question 17

Determine the equilibrium constant Kp at 25$\circ$C for the reaction N2(g) + 3H2(g) $\leftrightharpoons$ 2NH3(g).[$\Delta$G$\circ$f (NH3(g)) = -16.6 kJ/mol]

Accepted Answer

A)  1.52 * 10-6 
B)  6.60 * 105 
C)  8.28 * 10-2 
D)  2.60 
E)  13.4 
A)  1.52 * 10-6 
B)  6.60 * 105 
C)  8.28 * 10-2 
D)  2.60 
E)  13.4

Question 18

A sample of solid naphthalene is introduced into an evacuated flask. Use the data below to calculate the equilibrium vapor pressure of naphthalene (C10H8) in the flask at 35$\circ$C. $\begin{array}{lcc}
&\Delta \mathrm{H}^{\circ}{ }_{\mathrm{f}}\left(25^{\circ} \mathrm{C}\right) & \Delta \mathrm{G}^{\circ}_\mathrm{f}\left(25^{\circ} \mathrm{C}\right)\\hline
\mathrm{C}_{10} \mathrm{H}_{8}(\mathrm{s}) & 78.5 \mathrm{~kJ} / \mathrm{mol} & 201.6 \mathrm{~kJ} / \mathrm{mol} \
\mathrm{C}_{10} \mathrm{H}_{8}(\mathrm{g}) & 150.6 \mathrm{~kJ} / \mathrm{mol} & 224.1 \mathrm{~kJ} / \mathrm{mol}
\end{array}$

Accepted Answer

A)  890. mmHg 
B)  0.21 mmHg 
C)  696 mmHg 
D)  0.086 mmHg 
E)  833 mmHg 
A)  890. mmHg 
B)  0.21 mmHg 
C)  696 mmHg 
D)  0.086 mmHg 
E)  833 mmHg

Question 19

Which of the following is expected to have zero entropy
I. N2(g) at 273 K
II. SiO2(s, amorphous) at 0 K
III. NaCl(s) perfectly ordered crystal at 25 K
IV. Na(s) perfectly ordered crystal at 0 K

Accepted Answer

A)  I and IV 
B)  III and IV 
C)  I and II 
D)  I, II, and III 
E)  IV only 
A)  I and IV 
B)  III and IV 
C)  I and II 
D)  I, II, and III 
E)  IV only

Question 20

Which of the following is consistent with a reaction at equilibrium

Accepted Answer

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

Exam 17: Entropy Free Energy and Equilibrium

Calculate Kp at 298 K for the reaction SO2(g) + NO2(g) ⇋\leftrightharpoons⇋ SO3(g) + NO(g). \Delta () -300.4/ () -370.4/ () 86.7/ () 51.8/

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) Using the thermodynamic data provided below, calculate Δ\DeltaΔ S ∘\circ∘ for this reaction. (/\cdot) (s) 28.3 (g) 205.0 (s) 50.99

Find the temperature at which the reaction N2O4(g) ⇋\leftrightharpoons⇋ 2NO2(g) will be in equilibrium when both gases are present at partial pressures of 1.00 atm. \Delta 2 \Delta 2 () 33.85/ 51.8/ () 9.66/ 98.29/

At a given temperature, Br2(l) has a higher entropy per mole than Br2(g).

For the reaction H2(g) + S(s) →\rarr→ H2S(g), Δ\DeltaΔ H ∘\circ∘ = -20.2 kJ/mol and Δ\DeltaΔ S ∘\circ∘ = +43.1 J/K·mol. Which of these statements is true

Using the thermodynamic data provided below, calculate Ka1 for H2CO3(aq) at 25 ∘\circ∘ . \Delta(/) (/\cdot) (aq) 0 0 (aq) -698.7 191 (aq) -691.11 95.0 (aq) -676.26 -53.1

Assuming Δ\DeltaΔ S ∘\circ∘ and Δ\DeltaΔ H ∘\circ∘ do not vary with temperature, at what temperature will the reaction shown below become spontaneous C(s) + H2O(g) →\rarr→ H2(g) + CO(s) ( Δ\DeltaΔ S ∘\circ∘ = 133.6 J/K·mol; Δ\DeltaΔ H ∘\circ∘ = 131.3 kJ/mol)

Predict the signs (-, +, or 0) of Δ\DeltaΔ H and Δ\DeltaΔ S, in that order, for the reaction: O2(g) →\rarr→ 2O(g).

Predict the signs (-, +, or 0) of Δ\DeltaΔ H and Δ\DeltaΔ S, in that order, for the reaction: 6CO2(g) + 6H2O(g) →\rarr→ C6H12O6(g) + 6O2(g).

The heat of vaporization of water is 2.27 kJ/g. What is Δ\DeltaΔ Svap per mole at the normal boiling point

For any pure substance, if Δ\DeltaΔ Hf ∘\circ∘ = 0 and Δ\DeltaΔ Gf ∘\circ∘ = 0, then S ∘\circ∘ = 0.

Determine the equilibrium constant (Kp) at 25 ∘\circ∘ C for the reaction ()+()\leftrightharpoons()+(). \Delta=-28.5/

Which of the following is consistent with a nonspontaneous process in the forward direction

The reaction 3H2(g) + N2(g) ⇋\leftrightharpoons⇋ 2NH3(g),(Kc = 9.0 at 350 ∘\circ∘ C) proceeds from right to left at 350 ∘\circ∘ C under standard state conditions.

Determine the equilibrium constant Kp at 25 ∘\circ∘ C for the reaction N2(g) + 3H2(g) ⇋\leftrightharpoons⇋ 2NH3(g).[ Δ\DeltaΔ G ∘\circ∘ f (NH3(g)) = -16.6 kJ/mol]

A sample of solid naphthalene is introduced into an evacuated flask. Use the data below to calculate the equilibrium vapor pressure of naphthalene (C10H8) in the flask at 35 ∘\circ∘ C. \Delta 2 \Delta 2 () 78.5/ 201.6/ () 150.6/ 224.1/

Which of the following is expected to have zero entropy I. N2(g) at 273 K II. SiO2(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K

Which of the following is consistent with a reaction at equilibrium

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Filters

Calculate K_p at 298 K for the reaction SO₂(g) + NO₂(g) $\leftrightharpoons$ SO₃(g) + NO(g). \Delta () -300.4/ () -370.4/ () 86.7/ () 51.8/

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) Using the thermodynamic data provided below, calculate $\Delta$ S^$\circ$ for this reaction. (/\cdot) (s) 28.3 (g) 205.0 (s) 50.99

Find the temperature at which the reaction N₂O₄(g) $\leftrightharpoons$ 2NO₂(g) will be in equilibrium when both gases are present at partial pressures of 1.00 atm. \Delta 2 \Delta 2 () 33.85/ 51.8/ () 9.66/ 98.29/

At a given temperature, Br₂(l) has a higher entropy per mole than Br₂(g).

For the reaction H₂(g) + S(s) $\rarr$ H₂S(g), $\Delta$ H^$\circ$ = -20.2 kJ/mol and $\Delta$ S^$\circ$ = +43.1 J/K·mol. Which of these statements is true

Using the thermodynamic data provided below, calculate K_a1 for H₂CO₃(aq) at 25^$\circ$. \Delta(/) (/\cdot) (aq) 0 0 (aq) -698.7 191 (aq) -691.11 95.0 (aq) -676.26 -53.1

Assuming $\Delta$ S^$\circ$ and $\Delta$ H^$\circ$ do not vary with temperature, at what temperature will the reaction shown below become spontaneous C(s) + H₂O(g) $\rarr$ H₂(g) + CO(s) ( $\Delta$ S^$\circ$ = 133.6 J/K·mol; $\Delta$ H^$\circ$ = 131.3 kJ/mol)

Predict the signs (-, +, or 0) of $\Delta$ H and $\Delta$ S, in that order, for the reaction: O₂(g) $\rarr$ 2O(g).

Predict the signs (-, +, or 0) of $\Delta$ H and $\Delta$ S, in that order, for the reaction: 6CO₂(g) + 6H₂O(g) $\rarr$ C₆H₁₂O₆(g) + 6O₂(g).

The heat of vaporization of water is 2.27 kJ/g. What is $\Delta$ S_vap per mole at the normal boiling point

For any pure substance, if $\Delta$ H_f^$\circ$ = 0 and $\Delta$ G_f^$\circ$ = 0, then S^$\circ$ = 0.

Determine the equilibrium constant (K_p) at 25^$\circ$C for the reaction ()+()\leftrightharpoons()+(). \Delta=-28.5/

The reaction 3H₂(g) + N₂(g) $\leftrightharpoons$ 2NH₃(g),(K_c = 9.0 at 350^$\circ$C) proceeds from right to left at 350^$\circ$C under standard state conditions.

Determine the equilibrium constant K_p at 25^$\circ$C for the reaction N₂(g) + 3H₂(g) $\leftrightharpoons$ 2NH₃(g).[ $\Delta$ G^$\circ$_f (NH₃(g)) = -16.6 kJ/mol]

A sample of solid naphthalene is introduced into an evacuated flask. Use the data below to calculate the equilibrium vapor pressure of naphthalene (C₁₀H₈) in the flask at 35^$\circ$C. \Delta 2 \Delta 2 () 78.5/ 201.6/ () 150.6/ 224.1/

Which of the following is expected to have zero entropy I. N₂(g) at 273 K II. SiO₂(s, amorphous) at 0 K III. NaCl(s) perfectly ordered crystal at 25 K IV. Na(s) perfectly ordered crystal at 0 K