Question 1

Which of these species has the highest entropy (S°)at 25°C?

Accepted Answer

A) CO(g) 
B) CH4(g) 
C) NaCl(s) 
D) H2O(l) 
E) Fe(s) 
A) CO(g) 
B) CH4(g) 
C) NaCl(s) 
D) H2O(l) 
E) Fe(s) B

Question 2

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

Accepted Answer

110.J/K·mol

Question 3

Find the temperature at which the reaction N2O4(g)   2NO2(g)will be in equilibrium when both gases are present at partial pressures of 1.00 atm.

Accepted Answer

A) 300°C 
B) 28°C 
C) 55°C 
D) 32°C 
E) 562°C 
A) 300°C 
B) 28°C 
C) 55°C 
D) 32°C 
E) 562°C C

Question 4

Arrange these compounds in order of increasing standard molar entropy at 25°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 5

Which of the following processes would be accompanied by an increase in entropy?

Accepted Answer

A) H2O(g)$\rarr$ H2O(s) 
B) H2O(l)$\rarr$H2O(s) 
C) H2O(g)$\rarr$H2O(l) 
D) H2O(s)$\rarr$H2O(g) 
E) H2O(l, 50°
C) $\rarr$ H2O(l, 25°
C)  
A) H2O(g)$\rarr$ H2O(s) 
B) H2O(l)$\rarr$H2O(s) 
C) H2O(g)$\rarr$H2O(l) 
D) H2O(s)$\rarr$H2O(g) 
E) H2O(l, 50°
C) $\rarr$ H2O(l, 25°
C)

Question 6

Determine the equilibrium constant Kp at 25°C for the reaction N2(g)+ 3H2(g)     2NH3(g)
[$\Delta$G°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 7

Which of these species would you expect to have the highest standard entropy (S°)?

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 8

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° = 90.84 kJ/mol.
Estimate the temperature at which this reaction will become spontaneous under standard state conditions.
S°(Hg)= 76.02 J/K·mol
S°(O2)= 205.0 J/K·mol
S°(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 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

For a certain reaction, $\Delta$G° = 87 kJ/mol, $\Delta$H° = 100 kJ/mol at STP.At what temperature, in K, is the reaction in equilibrium, assuming that $\Delta$S° and $\Delta$H° are temperature-independent?

Accepted Answer

The answer of For a certain reaction, $\Delta$G° = 87...

Question 11

Assuming $\Delta$S° and $\Delta$H° 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° = 133.6 J/K·mol; $\Delta$H° = 131.3 kJ/mol)

Accepted Answer

Question 12

Ozone (O3)in the atmosphere can reaction with nitric oxide (NO): O3(g)+ NO(g)$\rarr$NO2(g)+ O2(g).
Calculate the $\Delta$G° for this reaction at 25°C.($\Delta$H° = -199 kJ/mol, $\Delta$S° = -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 13

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° for this reaction, given that $\Delta$G°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 14

For the reaction CuS(s)+ H2(g)    
H2S(g)+ Cu(s),
$\Delta$G°f (CuS)= -53.6 kJ/mol
$\Delta$G°f (H2S)= -33.6 kJ/mol
$\Delta$H°f (CuS)= -53.1 kJ/mol
$\Delta$H°f (H2S)= -20.6 kJ/mol
Calculate the value of the equilibrium constant (Kp)at 798 K and 1 atm pressure.

Accepted Answer

Question 15

Is the reaction SiO2(s)+ Pb(s)$\rarr$ PbO2(s)+ Si(s)spontaneous?
$\Delta$G°f (PbO2)= -217 kJ/mol
$\Delta$G°f (SiO2)= -856 kJ/mol

Accepted Answer

Question 16

For the reaction CuS(s)+ H2(g)    
H2S(g)+ Cu(s),
$\Delta$G°f (CuS)= -53.6 kJ/mol
$\Delta$G°f (H2S)= -33.6 kJ/mol
$\Delta$H°f (CuS)= -53.1 kJ/mol
$\Delta$H°f (H2S)= - 20.6 kJ/mol
Will this reaction proceed spontaneously at 298 K and 1 atm pressure?

Accepted Answer

Question 17

For the reaction 2C(graphite)+ H2(g)$\rarr$C2H2(g), $\Delta$G°= +209.2 kJ/mol at 25°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 18

Determine the equilibrium constant (Kp)at 25°C for the reaction

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 19

Using the thermodynamic data provided below, calculate Ksp for Mg(OH)2(s)at 25°.

Accepted Answer

8.90 × 10^-12 (agrees re

Question 20

Calculate $\Delta$S° for the reaction SO2(s)+ NO2(g)$\rarr$SO3(g)+ NO(g).

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

Exam 17: Entropy Free Energy and Equilibrium

Which of these species has the highest entropy (S°)at 25°C?

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

Find the temperature at which the reaction N2O4(g) 2NO2(g)will be in equilibrium when both gases are present at partial pressures of 1.00 atm.

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

Which of the following processes would be accompanied by an increase in entropy?

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

Which of these species would you expect to have the highest standard entropy (S°)?

Which of the following is consistent with a spontaneous endothermic reaction?

For a certain reaction, Δ\DeltaΔ G° = 87 kJ/mol, Δ\DeltaΔ H° = 100 kJ/mol at STP.At what temperature, in K, is the reaction in equilibrium, assuming that Δ\DeltaΔ S° and Δ\DeltaΔ H° are temperature-independent?

Assuming Δ\DeltaΔ S° and Δ\DeltaΔ H° 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° = 133.6 J/K·mol; Δ\DeltaΔ H° = 131.3 kJ/mol)

Ozone (O3)in the atmosphere can reaction with nitric oxide (NO): O3(g)+ NO(g) →\rarr→ NO2(g)+ O2(g). Calculate the Δ\DeltaΔ G° for this reaction at 25°C.( Δ\DeltaΔ H° = -199 kJ/mol, Δ\DeltaΔ S° = -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° for this reaction, given that Δ\DeltaΔ G°f of aluminum oxide is -1576.4 kJ/mol.

For the reaction CuS(s)+ H2(g) H2S(g)+ Cu(s), Δ\DeltaΔ G°f (CuS)= -53.6 kJ/mol Δ\DeltaΔ G°f (H2S)= -33.6 kJ/mol Δ\DeltaΔ H°f (CuS)= -53.1 kJ/mol Δ\DeltaΔ H°f (H2S)= -20.6 kJ/mol Calculate the value of the equilibrium constant (Kp)at 798 K and 1 atm pressure.

Is the reaction SiO2(s)+ Pb(s) →\rarr→ PbO2(s)+ Si(s)spontaneous? Δ\DeltaΔ G°f (PbO2)= -217 kJ/mol Δ\DeltaΔ G°f (SiO2)= -856 kJ/mol

For the reaction CuS(s)+ H2(g) H2S(g)+ Cu(s), Δ\DeltaΔ G°f (CuS)= -53.6 kJ/mol Δ\DeltaΔ G°f (H2S)= -33.6 kJ/mol Δ\DeltaΔ H°f (CuS)= -53.1 kJ/mol Δ\DeltaΔ H°f (H2S)= - 20.6 kJ/mol Will this reaction proceed spontaneously at 298 K and 1 atm pressure?

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

Determine the equilibrium constant (Kp)at 25°C for the reaction

Using the thermodynamic data provided below, calculate Ksp for Mg(OH)2(s)at 25°.

Calculate Δ\DeltaΔ S° for the reaction SO2(s)+ NO2(g) →\rarr→ SO3(g)+ NO(g).

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

Find the temperature at which the reaction N₂O₄(g) 2NO₂(g)will be in equilibrium when both gases are present at partial pressures of 1.00 atm.

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

For a certain reaction, $\Delta$ G° = 87 kJ/mol, $\Delta$ H° = 100 kJ/mol at STP.At what temperature, in K, is the reaction in equilibrium, assuming that $\Delta$ S° and $\Delta$ H° are temperature-independent?

Assuming $\Delta$ S° and $\Delta$ H° 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° = 133.6 J/K·mol; $\Delta$ H° = 131.3 kJ/mol)

Ozone (O₃)in the atmosphere can reaction with nitric oxide (NO): O₃(g)+ NO(g) $\rarr$ NO₂(g)+ O₂(g). Calculate the $\Delta$ G° for this reaction at 25°C.( $\Delta$ H° = -199 kJ/mol, $\Delta$ S° = -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° for this reaction, given that $\Delta$ G°_f of aluminum oxide is -1576.4 kJ/mol.

Is the reaction SiO₂(s)+ Pb(s) $\rarr$ PbO₂(s)+ Si(s)spontaneous? $\Delta$ G°_f (PbO₂)= -217 kJ/mol $\Delta$ G°_f (SiO₂)= -856 kJ/mol

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

Determine the equilibrium constant (K_p)at 25°C for the reaction

Using the thermodynamic data provided below, calculate K_sp for Mg(OH)₂(s)at 25°.

Calculate $\Delta$ S° for the reaction SO₂(s)+ NO₂(g) $\rarr$ SO₃(g)+ NO(g). $Calculate \Delta S° for the reaction SO<sub>2</sub>(s)+ NO<sub>2</sub>(g) \rarr SO<sub>3</sub>(g)+ NO(g).$