Question 1

What does the third law of thermodynamics state?

Accepted Answer

A) It states that a substance that is perfectly crystalline at 0 K has an entropy of zero.​ 
B) It states that any quantity which has a continuous differentiable symmetry in the action has an associated conservation law.​ 
C) It states that if two systems are each in thermal equilibrium with a third,they are also in thermal equilibrium with each other.​ 
D) It states that the increase in internal energy of a closed system is equal to the difference between the heat supplied to the system and the work done by the system. 
E) ​It states that the internal energy of an ideal gas is independent of its volume and pressure depending only on its temperature. 
A) It states that a substance that is perfectly crystalline at 0 K has an entropy of zero.​ 
B) It states that any quantity which has a continuous differentiable symmetry in the action has an associated conservation law.​ 
C) It states that if two systems are each in thermal equilibrium with a third,they are also in thermal equilibrium with each other.​ 
D) It states that the increase in internal energy of a closed system is equal to the difference between the heat supplied to the system and the work done by the system. 
E) ​It states that the internal energy of an ideal gas is independent of its volume and pressure depending only on its temperature.

Question 2

In which of the following scenarios is no change in the internal energy of the system possible?

Accepted Answer

A) q 0 B) q > 0,w > 0 C) q = 0,w > 0 D) q < 0,w = 0 E) q < 0,w < 0 A) q 0 B) q > 0,w > 0 C) q = 0,w > 0 D) q < 0,w = 0 E) q < 0,w < 0

Question 3

Based on the following data,what is the standard Gibbs free energy of formation of the sulfate ion at 298 K? (R = 8.31 J/(K ∙ mol))
PbSO4(s)  Pb2+(aq)+ SO42-(aq); Ksp = 1.7 × 10-8

Accepted Answer

A) -788.6 kJ/mol 
B) -793.1 kJ/mol 
C) -837.4 kJ/mol 
D) -744.3 kJ/mol 
E) 832.9 kJ/mol 
A) -788.6 kJ/mol 
B) -793.1 kJ/mol 
C) -837.4 kJ/mol 
D) -744.3 kJ/mol 
E) 832.9 kJ/mol

Question 4

Which of the following reactions has the smallest value of ΔS° at 25°C?

Accepted Answer

A) C6H6(l)+ 9/2O2(g)→ 6CO(g)+ 3H2O(g) 
B) C6H6(s)→ C6H6(l) 
C) C6H6(l)+ Br2(l)→ C6H5Br(l)+ HBr(g) 
D) C6H6(s)→ C6H6(g) 
E) C6H6(l)+ 15/2O2(g)→ 6CO2(g)+ 3H2O(g) 
A) C6H6(l)+ 9/2O2(g)→ 6CO(g)+ 3H2O(g) 
B) C6H6(s)→ C6H6(l) 
C) C6H6(l)+ Br2(l)→ C6H5Br(l)+ HBr(g) 
D) C6H6(s)→ C6H6(g) 
E) C6H6(l)+ 15/2O2(g)→ 6CO2(g)+ 3H2O(g)

Question 5

Which of the following equations is correct?

Accepted Answer

A) G = S - TH 
B) G = H - PV 
C) G = H - TS 
D) ΔG = Ginitial - Gfinal 
E) G = S - PV 
A) G = S - TH 
B) G = H - PV 
C) G = H - TS 
D) ΔG = Ginitial - Gfinal 
E) G = S - PV

Question 6

Under standard-state conditions,a reaction with ΔH°  0 is

Accepted Answer

A) not spontaneous at low temperatures but spontaneous at high temperatures. 
B) at equilibrium. 
C) spontaneous at any temperature. 
D) spontaneous at low temperatures but not at high temperatures. 
E) not spontaneous at any temperature. 
A) not spontaneous at low temperatures but spontaneous at high temperatures. 
B) at equilibrium. 
C) spontaneous at any temperature. 
D) spontaneous at low temperatures but not at high temperatures. 
E) not spontaneous at any temperature.

Question 7

For the reaction 2SO2(g)+ O2(g)→ 2SO3(g),ΔH° and ΔS° are both negative at 298 K,and the process is spontaneous at 298 K.Which of the following statements must also be true?

Accepted Answer

A) The change in entropy is the driving force of the reaction. 
B) ΔG is positive for the reaction at 298 K. 
C) The direction of the reaction may be reversed at high temperatures. 
D) ΔG is temperature independent. 
E) At high temperature,ΔH becomes positive. 
A) The change in entropy is the driving force of the reaction. 
B) ΔG is positive for the reaction at 298 K. 
C) The direction of the reaction may be reversed at high temperatures. 
D) ΔG is temperature independent. 
E) At high temperature,ΔH becomes positive.

Question 8

What is the change in entropy when 0.517 g of water decomposes to form hydrogen gas and oxygen gas at 298 K?
2H2O(l)→ 2H2(g)+ O2(g); ΔS° = 326.3 J/K at 298 K

Accepted Answer

A) 4.68 J/K 
B) 0.0628 J/K 
C) 18.7 J/K 
D) 9.36 J/K 
E) 168 J/K 
A) 4.68 J/K 
B) 0.0628 J/K 
C) 18.7 J/K 
D) 9.36 J/K 
E) 168 J/K

Question 9

Consider the following reaction,which is spontaneous at room temperature.
NH3(g)+ BF3(g)→ H3NBF3(s)
One would predict that

Accepted Answer

A) ΔG is negative at all temperatures. 
B) ΔH is positive and ΔS is negative for the reaction. 
C) ΔH is negative and ΔS is positive for the reaction. 
D) ΔH is positive and ΔS is positive for the reaction. 
E) ΔH is negative and ΔS is negative for the reaction. 
A) ΔG is negative at all temperatures. 
B) ΔH is positive and ΔS is negative for the reaction. 
C) ΔH is negative and ΔS is positive for the reaction. 
D) ΔH is positive and ΔS is positive for the reaction. 
E) ΔH is negative and ΔS is negative for the reaction.

Question 10

The total entropy of a system and its surroundings always increases for a spontaneous process.This is a statement of

Accepted Answer

A) the third law of thermodynamics. 
B) the law of constant composition. 
C) the second law of thermodynamics. 
D) the law of conservation of matter. 
E) the first law of thermodynamics. 
A) the third law of thermodynamics. 
B) the law of constant composition. 
C) the second law of thermodynamics. 
D) the law of conservation of matter. 
E) the first law of thermodynamics.

Question 11

For a particular process,q = 20 kJ and w = 15 kJ.Which of the following statements is true?

Accepted Answer

A) ΔU = 35 kJ. 
B) The system does work on the surroundings. 
C) Heat flows from the system to the surroundings. 
D) All of the above are true. 
E) None of the above are true. 
A) ΔU = 35 kJ. 
B) The system does work on the surroundings. 
C) Heat flows from the system to the surroundings. 
D) All of the above are true. 
E) None of the above are true.

Question 12

The standard enthalpy of fusion of iodobenzene is 9.75 kJ/mol at its melting point,241.8 K.What is the standard change in entropy for the melting of iodobenzene at its melting point?

Accepted Answer

A) 0.0189 J/(mol ∙ K) 
B) 40.3 J/(mol ∙ K) 
C) 9.75 J/(mol ∙ K) 
D) 311 J/(mol ∙ K) 
E) 0.0403 J/(mol ∙ K) 
A) 0.0189 J/(mol ∙ K) 
B) 40.3 J/(mol ∙ K) 
C) 9.75 J/(mol ∙ K) 
D) 311 J/(mol ∙ K) 
E) 0.0403 J/(mol ∙ K)

Question 13

The standard enthalpy of vaporization of methanol is 35.2 kJ/mol at its normal boiling point,64.6°C.What is the standard change in entropy for the vaporization of methanol at its normal boiling point?

Accepted Answer

A) 104 J/(mol ∙ K) 
B) 35.2 J/(mol ∙ K) 
C) 0.544 J/(mol ∙ K) 
D) 0.104 J/(mol ∙ K) 
E) 544 J/(mol ∙ K) 
A) 104 J/(mol ∙ K) 
B) 35.2 J/(mol ∙ K) 
C) 0.544 J/(mol ∙ K) 
D) 0.104 J/(mol ∙ K) 
E) 544 J/(mol ∙ K)

Question 14

-Given the following,determine ΔG° at 298 K for the precipitation reaction,
Ag+(aq)+I−(aq)→ AgI(s)

Accepted Answer

A) -91.7 kJ/mol 
B) -40.7 kJ/mol 
C) 91.7 kJ/mol 
D) 40.7 kJ/mol 
E) 62.5 kJ/mol 
A) -91.7 kJ/mol 
B) -40.7 kJ/mol 
C) 91.7 kJ/mol 
D) 40.7 kJ/mol 
E) 62.5 kJ/mol

Question 15

The enthalpy of vaporization (ΔH°vap)of benzene is 30.7 kJ/mol at its normal boiling point of 353.3 K.What is ΔS°vap at this temperature?

Accepted Answer

A) 86.9 J/(mol·K) 
B) 0.087 J/(mol·K) 
C) 11.5 J/(mol·K) 
D) 0.0115 J/(mol·K) 
E) 383 J/(mol·K) 
A) 86.9 J/(mol·K) 
B) 0.087 J/(mol·K) 
C) 11.5 J/(mol·K) 
D) 0.0115 J/(mol·K) 
E) 383 J/(mol·K)

Question 16

For a reaction system that is at equilibrium,which of the following must always be true?

Accepted Answer

A) ΔH = 0 
B) ΔS = 0 
C) ΔG = 0 
D) q = 0 
E) ΔU = 0 
A) ΔH = 0 
B) ΔS = 0 
C) ΔG = 0 
D) q = 0 
E) ΔU = 0

Question 17

In which reaction is ΔS° expected to be negative?

Accepted Answer

A) 2C2H6(g)+ 7O2(g)→ 4CO2(g)+ 6H2O(l) 
B) Ga(l)→ Ga(s) 
C) H2O(l)+ 2SO2(g)→ H2SO4(l) 
D) CO2(g)→ CO2(s) 
E) all of above 
A) 2C2H6(g)+ 7O2(g)→ 4CO2(g)+ 6H2O(l) 
B) Ga(l)→ Ga(s) 
C) H2O(l)+ 2SO2(g)→ H2SO4(l) 
D) CO2(g)→ CO2(s) 
E) all of above

Question 18

The standard free energy of formation of nitric oxide,NO,at 1000.K (roughly the temperature in an automobile engine during ignition)is 77.7 kJ/mol.Calculate the equilibrium constant for the reaction    
2NO(g)
At 1000.K.(R = 8.31 J/(K ∙ mol))

Accepted Answer

A) 0.95 
B) 7.6 × 10-9 
C) 1.6 × 105 
D) -15 
E) 8.7 × 10-5 
A) 0.95 
B) 7.6 × 10-9 
C) 1.6 × 105 
D) -15 
E) 8.7 × 10-5

Question 19

If a process is both endothermic and spontaneous,then

Accepted Answer

A) ΔH = 0. B) ΔG > 0. C) ΔS > 0. D) ΔU < 0. E) ΔH < 0. A) ΔH = 0. B) ΔG > 0. C) ΔS > 0. D) ΔU < 0. E) ΔH < 0.

Question 20

Which of the following is not a spontaneous process at 25°C and 1 atm pressure?

Accepted Answer

A) salt dissolving 
B) ice melting 
C) water boiling 
D) iron rusting 
E) steam condensing 
A) salt dissolving 
B) ice melting 
C) water boiling 
D) iron rusting 
E) steam condensing

Exam 18: Thermodynamics and Equilibrium

What does the third law of thermodynamics state?

In which of the following scenarios is no change in the internal energy of the system possible?

Based on the following data,what is the standard Gibbs free energy of formation of the sulfate ion at 298 K? (R = 8.31 J/(K ∙ mol)) PbSO4(s) Pb2+(aq)+ SO42-(aq); Ksp = 1.7 × 10-8

Which of the following reactions has the smallest value of ΔS° at 25°C?

Which of the following equations is correct?

Under standard-state conditions,a reaction with ΔH° < 0 and ΔS° > 0 is

For the reaction 2SO2(g)+ O2(g)→ 2SO3(g),ΔH° and ΔS° are both negative at 298 K,and the process is spontaneous at 298 K.Which of the following statements must also be true?

What is the change in entropy when 0.517 g of water decomposes to form hydrogen gas and oxygen gas at 298 K? 2H2O(l)→ 2H2(g)+ O2(g); ΔS° = 326.3 J/K at 298 K

Consider the following reaction,which is spontaneous at room temperature. NH3(g)+ BF3(g)→ H3NBF3(s) One would predict that

The total entropy of a system and its surroundings always increases for a spontaneous process.This is a statement of

For a particular process,q = 20 kJ and w = 15 kJ.Which of the following statements is true?

The standard enthalpy of fusion of iodobenzene is 9.75 kJ/mol at its melting point,241.8 K.What is the standard change in entropy for the melting of iodobenzene at its melting point?

The standard enthalpy of vaporization of methanol is 35.2 kJ/mol at its normal boiling point,64.6°C.What is the standard change in entropy for the vaporization of methanol at its normal boiling point?

-Given the following,determine ΔG° at 298 K for the precipitation reaction, Ag+(aq)+I−(aq)→ AgI(s)

The enthalpy of vaporization (ΔH°vap)of benzene is 30.7 kJ/mol at its normal boiling point of 353.3 K.What is ΔS°vap at this temperature?

For a reaction system that is at equilibrium,which of the following must always be true?

In which reaction is ΔS° expected to be negative?

The standard free energy of formation of nitric oxide,NO,at 1000.K (roughly the temperature in an automobile engine during ignition)is 77.7 kJ/mol.Calculate the equilibrium constant for the reaction 2NO(g) At 1000.K.(R = 8.31 J/(K ∙ mol))

If a process is both endothermic and spontaneous,then

Which of the following is not a spontaneous process at 25°C and 1 atm pressure?

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Based on the following data,what is the standard Gibbs free energy of formation of the sulfate ion at 298 K? (R = 8.31 J/(K ∙ mol)) PbSO₄(s) Pb²⁺(aq)+ SO₄^2-(aq); K_sp = 1.7 × 10^-8

For the reaction 2SO₂(g)+ O₂(g)→ 2SO₃(g),ΔH° and ΔS° are both negative at 298 K,and the process is spontaneous at 298 K.Which of the following statements must also be true?

What is the change in entropy when 0.517 g of water decomposes to form hydrogen gas and oxygen gas at 298 K? 2H₂O(l)→ 2H₂(g)+ O₂(g); ΔS° = 326.3 J/K at 298 K

Consider the following reaction,which is spontaneous at room temperature. NH₃(g)+ BF₃(g)→ H₃NBF₃(s) One would predict that

-Given the following,determine ΔG° at 298 K for the precipitation reaction, Ag⁺(aq)+I−(aq)→ AgI(s)

The enthalpy of vaporization (ΔH°_vap)of benzene is 30.7 kJ/mol at its normal boiling point of 353.3 K.What is ΔS°_vap at this temperature?