Question 1

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 2

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

Accepted Answer

A) CH4(g) 
B) HF(g) 
C) NH3(g) 
D) H2O(g) 
A) CH4(g) 
B) HF(g) 
C) NH3(g) 
D) H2O(g)

Question 3

Choose the substance with the higher entropy per mole at a given temperature: O2(g)at 5 atm or O2(g)at 0.5 atm.

Accepted Answer

Question 4

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium nitrate is dissolved in water?   Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased?

Accepted Answer

90.4 J/K·mol; solubi

Question 5

Given the following data, calculate the boiling point of HCOOH (formic acid).

Accepted Answer

The answer of Given the following data, calculate the boiling...

Question 6

A spontaneous endothermic reaction always

Accepted Answer

A) causes the surroundings to get colder. 
B) bursts into flame. 
C) requires a spark to initiate it. 
D) releases heat to the surroundings. 
A) causes the surroundings to get colder. 
B) bursts into flame. 
C) requires a spark to initiate it. 
D) releases heat to the surroundings.

Question 7

Predict the sign of $\Delta$S for the process Ni(s, 50°C)$\to$ Ni(s, 25°C).

Accepted Answer

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

Question 8

Consider the reaction CO(g)+ 2H2(g)   CH3OH(l)at 25°C.
$\Delta$G°f (CO)= -137.3 kJ/mol
$\Delta$G°f (CH3OH)= -166.3 kJ/mol
$\Delta$H°f (CO)= -110.5 kJ/mol
$\Delta$H°f (CH3OH)= -238.7 kJ/mol
S°(CO)= 197.9 J/K·mol
S°(CH3OH)= 126.8 J/K·mol
Calculate S°(H2(g)).

Accepted Answer

The answer of Consider the reaction CO(g)+ 2H2(g)  ...

Question 9

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 10

Determine $\Delta$S° for the reaction SO3(g)+ H2O(l)$\to$0 H2SO4(l).

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 11

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

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 12

Melting an ionic solid always results in an increase in entropy.

Accepted Answer

A) True 
 B)False

Question 13

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium sulfate is dissolved in water?   Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased?

Accepted Answer

-11.84 J/K·mol; solu

Question 14

Predict the sign of $\Delta$S for the process N2(g, 10 atm)$\to$ N2(g, 1atm).

Accepted Answer

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

Question 15

Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s)$\to$ Na2CO3(s)+ CO2(g)+ H2O(g)
Given that $\Delta$H° = 128.9 kJ/mol and $\Delta$G° = 33.1 kJ/mol at 25°C, above what minimum temperature will the reaction become spontaneous under standard state conditions?

Accepted Answer

A) 0.4 K 
B) 3.9 K 
C) 321 K 
D) 401 K 
E) 525 K 
A) 0.4 K 
B) 3.9 K 
C) 321 K 
D) 401 K 
E) 525 K

Question 16

For the reaction 3H2(g)+ N2(g)   2NH3(g), Kc = 9.0 at 350°C. In what direction does the reaction proceed when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor?

Accepted Answer

Question 17

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 $\Delta$G at 798 K and 1 atm pressure (assume $\Delta$S° and $\Delta$H° do not change with temperature).

Accepted Answer

The answer of For the reaction CuS(s)+ H2(g)  ...

Question 18

Sulfur can be separated from lead in the mineral galena, PbS(s), by "roasting" the ore in the presence of oxygen as shown in the following reaction: 2PbS(s)+ 3O2(g)$\to$ 2PbO(s)+ 2SO2(g)
Calculate $\Delta$S° for this reaction using the thermodynamic data provided below.

Accepted Answer

A) -410 J/K·mol 
B) -161.5 J/K·mol 
C) -47.7 J/K·mol 
D) 21.8 J/K·mol 
E) 43.5 J/K·mol 
A) -410 J/K·mol 
B) -161.5 J/K·mol 
C) -47.7 J/K·mol 
D) 21.8 J/K·mol 
E) 43.5 J/K·mol

Question 19

Which response includes all of the following processes that are accompanied by an increase in entropy? 
1)I2(s)$\to$ I2(g)
2)2I(g)$\to$ I2(g)
3)2NH3(g)$\to$N2(g)+ 3H2(g)
4)Mg2+(aq)+ 2OH-(aq)$\to$ Mg(OH)2(s)

Accepted Answer

A) 1, 2 
B) 1, 3 
C) 3, 4 
D) 3 
E) 2, 4 
A) 1, 2 
B) 1, 3 
C) 3, 4 
D) 3 
E) 2, 4

Question 20

How does the entropy change when a solid is melted?

Accepted Answer

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

Exam 18: Entropy, Free Energy, and Equilibrium

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

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

Choose the substance with the higher entropy per mole at a given temperature: O2(g)at 5 atm or O2(g)at 0.5 atm.

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium nitrate is dissolved in water? Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased?

Given the following data, calculate the boiling point of HCOOH (formic acid).

A spontaneous endothermic reaction always

Predict the sign of Δ\DeltaΔ S for the process Ni(s, 50°C) →\to→ Ni(s, 25°C).

Consider the reaction CO(g)+ 2H2(g) CH3OH(l)at 25°C. Δ\DeltaΔ G°f (CO)= -137.3 kJ/mol Δ\DeltaΔ G°f (CH3OH)= -166.3 kJ/mol Δ\DeltaΔ H°f (CO)= -110.5 kJ/mol Δ\DeltaΔ H°f (CH3OH)= -238.7 kJ/mol S°(CO)= 197.9 J/K·mol S°(CH3OH)= 126.8 J/K·mol Calculate S°(H2(g)).

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

Determine Δ\DeltaΔ S° for the reaction SO3(g)+ H2O(l) →\to→ 0 H2SO4(l).

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

Melting an ionic solid always results in an increase in entropy.

Using the thermodynamic data provided below, calculate the standard change in entropy when one mole of sodium sulfate is dissolved in water? Will the solubility of sodium nitrate increase or decrease if the temperature of the system is increased?

Predict the sign of Δ\DeltaΔ S for the process N2(g, 10 atm) →\to→ N2(g, 1atm).

Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s) →\to→ Na2CO3(s)+ CO2(g)+ H2O(g) Given that Δ\DeltaΔ H° = 128.9 kJ/mol and Δ\DeltaΔ G° = 33.1 kJ/mol at 25°C, above what minimum temperature will the reaction become spontaneous under standard state conditions?

For the reaction 3H2(g)+ N2(g) 2NH3(g), Kc = 9.0 at 350°C. In what direction does the reaction proceed when 1.0 mol NH3, 5.0 mol N2, and 5.0 mol H2 are mixed in a 2.5 L reactor?

Sulfur can be separated from lead in the mineral galena, PbS(s), by "roasting" the ore in the presence of oxygen as shown in the following reaction: 2PbS(s)+ 3O2(g) →\to→ 2PbO(s)+ 2SO2(g) Calculate Δ\DeltaΔ S° for this reaction using the thermodynamic data provided below.

Which response includes all of the following processes that are accompanied by an increase in entropy? 1)I2(s) →\to→ I2(g) 2)2I(g) →\to→ I2(g) 3)2NH3(g) →\to→ N2(g)+ 3H2(g) 4)Mg2+(aq)+ 2OH-(aq) →\to→ Mg(OH)2(s)

How does the entropy change when a solid is melted?

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

Choose the substance with the higher entropy per mole at a given temperature: O₂(g)at 5 atm or O₂(g)at 0.5 atm.

Predict the sign of $\Delta$ S for the process Ni(s, 50°C) $\to$ Ni(s, 25°C).

Determine $\Delta$ S° for the reaction SO₃(g)+ H₂O(l) $\to$ 0 H₂SO₄(l). $Determine \Delta S° for the reaction SO<sub>3</sub>(g)+ H<sub>2</sub>O(l) \to 0 H<sub>2</sub>SO<sub>4</sub>(l).$

Predict the sign of $\Delta$ S for the process N₂(g, 10 atm) $\to$ N₂(g, 1atm).

Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO₃(s) $\to$ Na₂CO₃(s)+ CO₂(g)+ H₂O(g) Given that $\Delta$ H° = 128.9 kJ/mol and $\Delta$ G° = 33.1 kJ/mol at 25°C, above what minimum temperature will the reaction become spontaneous under standard state conditions?

For the reaction 3H₂(g)+ N₂(g) 2NH₃(g), K_c = 9.0 at 350°C. In what direction does the reaction proceed when 1.0 mol NH₃, 5.0 mol N₂, and 5.0 mol H₂ are mixed in a 2.5 L reactor?

Which response includes all of the following processes that are accompanied by an increase in entropy? 1)I₂(s) $\to$ I₂(g) 2)2I(g) $\to$ I₂(g) 3)2NH₃(g) $\to$ N₂(g)+ 3H₂(g) 4)Mg²⁺(aq)+ 2OH^-(aq) $\to$ Mg(OH)₂(s)