Question 1

Which species will have the lowest absolute entropy at 25°C?

Accepted Answer

A) C2H5OH(l) 
B) C2H2(g) 
C) C3H8(g) 
D) C3H7OH(l) 
E) C2H6(g) 
A) C2H5OH(l) 
B) C2H2(g) 
C) C3H8(g) 
D) C3H7OH(l) 
E) C2H6(g)

Question 2

Arrange the following substances in the order of increasing entropy at 25°C. HF(g), NaF(s), SiF4(g), SiH4(g), Al(s)
Lowest $\to$ 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 3

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

Accepted Answer

8.90 @#LAT-DLM& 10^-1²

Question 4

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion. 4Al(s)+ 3O2(g)$\to$2Al2O3(s)
Using the thermodynamic data provided below, calculate $\Delta$S° for this reaction.

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 5

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 6

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)for this reaction at 298 K.

Accepted Answer

3.11 @#LAT-DLM& 10<s

Question 7

Hydrogen peroxide (H2O2)decomposes according to the equation H2O2(l)$\to\0 H2O(l)+ 1/2O2(g).
Calculate Kp for this reaction at 25°C. (\(\Delta$H° = -98.2 kJ/mol, $\Delta$S° = 70.1 J/K·mol)

Accepted Answer

A) 1.3 $\times$ 10-21 
B) 20.9 
C) 3.46 $\times$ 1017. 
D) 7.5 $\times$ 1020 
E) 8.6 $\times$ 104 
A) 1.3 $\times$ 10-21 
B) 20.9 
C) 3.46 $\times$ 1017. 
D) 7.5 $\times$ 1020 
E) 8.6 $\times$ 104

Question 8

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

Accepted Answer

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

Question 9

For the reaction H2O2(g)$\to$ H2O(g)+ 1/2O2(g), $\Delta$H° = -106 kJ/mol and $\Delta$S° = 58 J/K·mol at 25°C. Is H2O2(g)stable with respect to dissociation into water vapor and oxygen gas at 25°C?

Accepted Answer

The answer of For the reaction H2O2(g)$\to$ H2O(g)+ 1/2O2(g), $\Delta$H°...

Question 10

For the reaction SbCl5(g)   SbCl3(g)+ Cl2(g),
$\Delta$G°f (SbCl5)= -334.34 kJ/mol
$\Delta$G°f (SbCl3)= -301.25 kJ/mol
$\Delta$H°f (SbCl5)= -394.34 kJ/mol
$\Delta$H°f (SbCl3)= -313.80 kJ/mol
Calculate the value of the equilibrium constant (Kp)at 800 K and 1 atm pressure.

Accepted Answer

1.11 @#LAT-DLM& 10<s

Question 11

Predict the sign of $\Delta$S for the reaction O2(g)$\to$ 2O(g).

Accepted Answer

The answer of Predict the sign of $\Delta$S for the...

Question 12

Using the thermodynamic data provided below, calculate Ka for HCN(aq)at 25°.

Accepted Answer

2.8 @#LAT-DLM& 10^-9

Question 13

Ozone (O3)in the atmosphere can reaction with nitric oxide (NO): O3(g)+ NO(g)$\to$ 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 $\times$ 103 kJ/mol 
C) 2.00 $\times$ 103 kJ/mol 
D) -1.42 $\times$ 103 kJ/mol 
E) -198 kJ/mol 
A) 1020 kJ/mol 
B) -1.22 $\times$ 103 kJ/mol 
C) 2.00 $\times$ 103 kJ/mol 
D) -1.42 $\times$ 103 kJ/mol 
E) -198 kJ/mol

Question 14

Using the thermodynamic data provided below, determine the temperature in °C at which the decomposition of solid calcium carbonate to form solid calcium oxide and oxygen becomes spontaneous.

Accepted Answer

The answer of Using the thermodynamic data provided below, determine...

Question 15

Kw for the auto-ionization of water, H2O(l)$\to$ H+(aq)+ OH- (aq), is 1.0 $\times$ 10-14. What are the signs (+/-)of $\Delta$S° and $\Delta$H° for the reaction at 25°C?

Accepted Answer

A) ($\Delta$S° = (+)and $\Delta$H° = (+)) 
B) ($\Delta$S° = (+)and $\Delta$H° = (-)) 
C) ($\Delta$S° = (-)and $\Delta$H° = (+)) 
D) ($\Delta$S° = (-)and $\Delta$H° = (-)) 
A) ($\Delta$S° = (+)and $\Delta$H° = (+)) 
B) ($\Delta$S° = (+)and $\Delta$H° = (-)) 
C) ($\Delta$S° = (-)and $\Delta$H° = (+)) 
D) ($\Delta$S° = (-)and $\Delta$H° = (-))

Question 16

HI has a normal boiling point of -35.4°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 17

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

Question 18

What is the free energy change for the reaction SiO2(s)+ Pb(s)$\to$PbO2(s)+ Si(s)?
$\Delta$G°f (PbO2)= -217 kJ/mol
$\Delta$G°f (SiO2)= -856 kJ/mol

Accepted Answer

The answer of What is the free energy change for...

Question 19

How does the entropy change when a molecular solid is dissolved in water?

Accepted Answer

The answer of How does the entropy change when a...

Question 20

For the reaction 3H2(g)+ N2(g)   2NH3(g), Kc = 9.0 at 350°C. Calculate $\Delta$G° at 350°C.

Accepted Answer

The answer of For the reaction 3H2(g)+ N2(g)  ...

Exam 18: Entropy, Free Energy, and Equilibrium

Which species will have the lowest absolute entropy at 25°C?

Arrange the following substances in the order of increasing entropy at 25°C. HF(g), NaF(s), SiF4(g), SiH4(g), Al(s) Lowest →\to→ highest

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

Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion. 4Al(s)+ 3O2(g) →\to→ 2Al2O3(s) Using the thermodynamic data provided below, calculate Δ\DeltaΔ S° for this 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?

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)for this reaction at 298 K.

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

For the reaction H2O2(g) →\to→ H2O(g)+ 1/2O2(g), Δ\DeltaΔ H° = -106 kJ/mol and Δ\DeltaΔ S° = 58 J/K·mol at 25°C. Is H2O2(g)stable with respect to dissociation into water vapor and oxygen gas at 25°C?

For the reaction SbCl5(g) SbCl3(g)+ Cl2(g), Δ\DeltaΔ G°f (SbCl5)= -334.34 kJ/mol Δ\DeltaΔ G°f (SbCl3)= -301.25 kJ/mol Δ\DeltaΔ H°f (SbCl5)= -394.34 kJ/mol Δ\DeltaΔ H°f (SbCl3)= -313.80 kJ/mol Calculate the value of the equilibrium constant (Kp)at 800 K and 1 atm pressure.

Predict the sign of Δ\DeltaΔ S for the reaction O2(g) →\to→ 2O(g).

Using the thermodynamic data provided below, calculate Ka for HCN(aq)at 25°.

Ozone (O3)in the atmosphere can reaction with nitric oxide (NO): O3(g)+ NO(g) →\to→ 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)

Using the thermodynamic data provided below, determine the temperature in °C at which the decomposition of solid calcium carbonate to form solid calcium oxide and oxygen becomes spontaneous.

Kw for the auto-ionization of water, H2O(l) →\to→ H+(aq)+ OH- (aq), is 1.0 ×\times× 10-14. What are the signs (+/-)of Δ\DeltaΔ S° and Δ\DeltaΔ H° for the reaction at 25°C?

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

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].

What is the free energy change for the reaction SiO2(s)+ Pb(s) →\to→ PbO2(s)+ Si(s)? Δ\DeltaΔ G°f (PbO2)= -217 kJ/mol Δ\DeltaΔ G°f (SiO2)= -856 kJ/mol

How does the entropy change when a molecular solid is dissolved in water?

For the reaction 3H2(g)+ N2(g) 2NH3(g), Kc = 9.0 at 350°C. Calculate Δ\DeltaΔ G° at 350°C.

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

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

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?

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

For the reaction H₂O₂(g) $\to$ H₂O(g)+ ¹/₂O₂(g), $\Delta$ H° = -106 kJ/mol and $\Delta$ S° = 58 J/K·mol at 25°C. Is H₂O₂(g)stable with respect to dissociation into water vapor and oxygen gas at 25°C?

Predict the sign of $\Delta$ S for the reaction O₂(g) $\to$ 2O(g).

Using the thermodynamic data provided below, calculate K_a for HCN(aq)at 25°.

Ozone (O₃)in the atmosphere can reaction with nitric oxide (NO): O₃(g)+ NO(g) $\to$ 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)

K_w for the auto-ionization of water, H₂O(l) $\to$ H⁺(aq)+ OH^- (aq), is 1.0 $\times$ 10^-14. What are the signs (+/-)of $\Delta$ S° and $\Delta$ H° for the reaction at 25°C?

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

What is the free energy change for the reaction SiO₂(s)+ Pb(s) $\to$ PbO₂(s)+ Si(s)? $\Delta$ G°_f (PbO₂)= -217 kJ/mol $\Delta$ G°_f (SiO₂)= -856 kJ/mol

For the reaction 3H₂(g)+ N₂(g) $For the reaction 3H<sub>2</sub>(g)+ N<sub>2</sub>(g) 2NH<sub>3</sub>(g), K<sub>c</sub> = 9.0 at 350°C. Calculate \Delta G° at 350°C.$ 2NH₃(g), K_c = 9.0 at 350°C. Calculate $\Delta$ G° at 350°C.