Question 1

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) A) and E)
G) A) and B)

Question 2

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

Accepted Answer

A) True 
 B)False

Question 3

For a reaction at equilibrium, ΔSuniv = 0.

Accepted Answer

A) True 
 B)False

Question 4

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 D)

Question 5

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

Accepted Answer

A) True 
 B)False

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 E)
G) A) and B)

Question 7

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) A) and E)
G) C) and D)

Question 8

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) A) and C)
G) None of the above

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

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

Accepted Answer

A) True 
 B)False

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) C) and D)
G) B) and C)

Question 12

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) C) and D)
G) None of the above

Question 13

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) A) and B)
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) C) and D)
G) A) and D)

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) C) and D)
G) A) and D)

Question 16

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) C) and D)
G) A) and D)

Question 17

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 E)
G) D) and E)

Question 18

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

Accepted Answer

A) True 
 B)False

Question 19

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) B) and E)
G) B) and C)

Question 20

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 E)
G) A) and B)

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

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

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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? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

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

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For a reaction at equilibrium, ΔSuniv = 0.

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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? CaO(s) + CO2(g) → CaCO3(s)

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

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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?

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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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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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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?

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

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

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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

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

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

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

Correct Answer
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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? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

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For a reaction at equilibrium, ΔS_univ = 0.

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

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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? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

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?

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

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

Correct Answer
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