Question 1

The free energy of a perfect crystal at absolute zero, is zero.

Accepted Answer

A) True 
 B)False

Question 2

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.2NO(g)  + Cl2(g)  → 2NOCl(g)   What is the value of ΔG° for this reaction at 550 K?

Accepted Answer

A)  -143.76 kJ
B)  -78.78 kJ
C)  -22.24 kJ
D)  -10.56 kJ
E)  66600 kJF) A) and D)
G) None of the above

Question 3

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

Accepted Answer

A)  Δ S° > 0, Δ H° > 0
B)  Δ S° > 0, Δ H° 
C)  Δ S° 
D)  Δ S°  0
E)  Δ G° > 0F) All of the above
G) A) and B)

Question 4

A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that ΔG = ΔG°. What conclusion can reasonably be drawn about the reaction at this time?

Accepted Answer

A)  K > Q
B)  K 
C)  K = Q
D)  K = 1
E)  Q = 1F) A) and C)
G) A) and B)

Question 5

Which relationship or statement best describes ΔS° for the following reaction? 2H2S(g)  + 3O2(g)  → 2H2O(g)  + 2SO2(g)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = Δ H°/ T
E)  More information is needed to make a reasonable prediction.F) C) and D)
G) All of the above

Question 6

Which relationship or statement best describes ΔS° for the following reaction? CaO(s)  + CO2(g)  → CaCO3(s)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = Δ H°/ T
E)  More information is needed to make a reasonable prediction.F) A) and B)
G) D) and E)

Question 7

For a reaction at equilibrium, ΔSuniv = 0.

Accepted Answer

A) True 
 B)False

Question 8

For any reaction, if ΔG° > 0, then K < 1.

Accepted Answer

A) True 
 B)False

Question 9

For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

Accepted Answer

A)  Δ S° > 0, Δ H° > 0
B)  Δ S° > 0, Δ H° 
C)  Δ S° 
D)  Δ S°  0
E)  All reactions are spontaneous at some temperature.F) A) and B)
G) A) and C)

Question 10

Calculate ΔS° for the reaction 2Cl2(g)  + SO2(g)  → SOCl2(g)  + Cl2O(g) 
2(g)  + SO2(g)  → SOCl2(g)  + Cl2O(g)    A) −118.2 J/K B) −104.8 J/K C) 104.8 J/K D) 118.2 J/K E) 1270.0 J/K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  −118.2 J/K
B)  −104.8 J/K
C)  104.8 J/K
D)  118.2 J/K
E)  1270.0 J/KF) B) and E)
G) A) and E)

Question 11

Which relationship or statement best describes ΔS° for the following reaction? BaCl2(aq)  + Na2SO4(aq)  → BaSO4(s)  + 2NaCl(aq)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = H°/ T
E)  More information is needed to make a reasonable prediction.F) B) and E)
G) D) and E)

Question 12

Under a given set of conditions, all microstates of a system are equally probable.

Accepted Answer

A) True 
 B)False

Question 13

Consider the reaction CuI(s)  ⇄ Cu+(aq)  + I−(aq) 
If the concentrations of the Cu+ and I− ions in equilibrium at 298 K are both equal to 1.03 × 10−6 M, what is the value of ΔG° for the reaction?

Accepted Answer

A)  −68 kJ
B)  68 kJ
C)  −30 kJ
D)  30 kJ
E)  34 kJF) B) and C)
G) C) and D)

Question 14

Which relationship or statement best describes ΔS° for the following reaction? O3(g)  + NO(g)  → O2(g)  + NO2(g)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = ΔH°/T
E)  More information is needed to make a reasonable prediction.F) B) and D)
G) A) and B)

Question 15

Which relationship or statement best describes ΔS° for the following reaction? HgS(s)  + O2(g)  → Hg(l)  + SO2(g)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = Δ H°/ T
E)  More information is needed to make a reasonable prediction.F) A) and D)
G) None of the above

Question 16

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Accepted Answer

A)  1 mole He( g) ; 1 mole Kr( g) 
B)  1 mole O 2( g) ; 2 mole O( g) 
C)  1 mole CH 4( g) ; 1 mole C 2H 6( g) 
D)  1 mole Xe( g) at 1 atmosphere; 1 mole Xe( g) at 0.5 atmosphere
E)  20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 peopleF) B) and D)
G) A) and E)

Question 17

Which relationship best describes ΔS° for the following reaction? 8H2(g)  + S8(s)  → 8H2S(g)

Accepted Answer

A)  Δ S° = Δ H°
B)  Δ S° = Δ H°/ T
C)  Δ S° ≈ 0
D)  Δ S° 
E)  Δ S° > 0F) B) and E)
G) C) and D)

Question 18

Which relationship or statement best describes ΔS° for the following reaction? Pb(s)  + Cl2(g)  → PbCl2(s)

Accepted Answer

A)  Δ S° ≈ 0
B)  Δ S° 
C)  Δ S° > 0
D)  Δ S° = Δ H°/T
E)  More information is needed to make a reasonable prediction.F) B) and D)
G) B) and E)

Question 19

In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II)  oxide: HgO(s)  → Hg(l)  + ½O2(g) 
For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Accepted Answer

A)  The reaction is only spontaneous at low temperatures.
B)  The reaction is spontaneous at all temperatures.
C)  ΔG° becomes less favorable as the temperature is raised.
D)  The reaction is spontaneous only at high temperatures.
E)  The reaction is spontaneous under standard conditions at 25°C.F) A) and B)
G) A) and C)

Question 20

The higher the pressure of a gas sample, the greater is its entropy.

Accepted Answer

A) True 
 B)False

Exam 20: Thermodynamics: Entropy, Free Energy, and Reaction Direction

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

Correct AnswerverifiedShow Answer

In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O2(g) For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Correct AnswerverifiedShow Answer

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl2(g) → PbCl2(s)

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In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

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The higher the pressure of a gas sample, the greater is its entropy.

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Which relationship or statement best describes ΔS° for the following reaction? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

Correct AnswerverifiedShow Answer

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.2NO(g) + Cl2(g) → 2NOCl(g) What is the value of ΔG° for this reaction at 550 K?

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Consider the reaction CuI(s) ⇄ Cu+(aq) + I−(aq) If the concentrations of the Cu+ and I− ions in equilibrium at 298 K are both equal to 1.03 × 10−6 M, what is the value of ΔG° for the reaction?

Correct AnswerverifiedShow Answer

Which relationship best describes ΔS° for the following reaction? 8H2(g) + S8(s) → 8H2S(g)

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The free energy of a perfect crystal at absolute zero, is zero.

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For a reaction at equilibrium, ΔSuniv = 0.

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Calculate ΔS° for the reaction 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

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For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

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Which relationship or statement best describes ΔS° for the following reaction? O3(g) + NO(g) → O2(g) + NO2(g)

Correct AnswerverifiedShow Answer

A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that ΔG = ΔG°. What conclusion can reasonably be drawn about the reaction at this time?

Correct AnswerverifiedShow Answer

Under a given set of conditions, all microstates of a system are equally probable.

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Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O2(g) → Hg(l) + SO2(g)

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Which relationship or statement best describes ΔS° for the following reaction? 2H2S(g) + 3O2(g) → 2H2O(g) + 2SO2(g)

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Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO2(g) → CaCO3(s)

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For any reaction, if ΔG° > 0, then K < 1.

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Correct Answer
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In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O₂(g) For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl₂(g) → PbCl₂(s)

Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

Correct Answer
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Correct Answer
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Consider the reaction CuI(s) ⇄ Cu⁺(aq) + I⁻(aq) If the concentrations of the Cu⁺ and I⁻ ions in equilibrium at 298 K are both equal to 1.03 × 10⁻⁶ M, what is the value of ΔG° for the reaction?

Correct Answer
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Which relationship best describes ΔS° for the following reaction? 8H₂(g) + S₈(s) → 8H₂S(g)

Correct Answer
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For a reaction at equilibrium, ΔS_univ = 0.

Correct Answer
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Calculate ΔS° for the reaction 2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

Correct Answer
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Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? O₃(g) + NO(g) → O₂(g) + NO₂(g)

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Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O₂(g) → Hg(l) + SO₂(g)

Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO₂(g) → CaCO₃(s)

Correct Answer
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Correct Answer
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