Question 1

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. H3PO4(s)  3PO4(s)    H3PO4(l)  Use the following thermodynamic information at 298 K to determine this temperature.   A)  286 K B)  305 K C)  315 K D)  347 K E)  3170 K" class="answers-bank-image d-inline" rel="preload" > H3PO4(l) 
Use the following thermodynamic information at 298 K to determine this temperature.
3PO4(s)    H3PO4(l)  Use the following thermodynamic information at 298 K to determine this temperature.   A)  286 K B)  305 K C)  315 K D)  347 K E)  3170 K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   286 K
B)   305 K
C)   315 K
D)   347 K
E)   3170 KF) A) and B)
G) D) and E)

Question 2

Which of the following should have the greatest molar entropy at 298 K?

Accepted Answer

A)   CH4(g) 
B)   H2O(l) 
C)   NaCl(s) 
D)   N2O4(g) 
E)   H2(g) F) C) and E)
G) None of the above D

Question 3

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

Accepted Answer

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

Question 4

Which relationship or statement best describes ΔS° for the following reaction? 2NH3(g)  + 2ClF3(g)  → 6HF(g)  + N2(g)  + Cl2(g)

Accepted Answer

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

Question 5

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

Accepted Answer

A)   ΔS° > 0, ΔH° > 0
B)   ΔS° > 0, ΔH° 
C)   ΔS° 
D)   ΔS°  0
E)   ΔG° > 0F) A) and D)
G) B) and E)

Question 6

Given: H2O(l)  → H2O(s)  ΔH° = -6.02 kJ at 273K Calculate the entropy change of the surroundings (ΔSsurr)  when one mole of water freezes at 0°C and a pressure of one atmosphere.

Accepted Answer

A)   22.1 J/K
B)   -22.1 J/K
C)   397 J/K
D)   -397 J/K
E)   0.022 J/KF) A) and C)
G) B) and E)

Question 7

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl3(g)  + 1.5H2(g)  → B(s)  + 3HCl(g) 
Substance: BCl3(g)  H2(g)  B(s)  HCl(g) 
S°(J/K·mol) : ? 130.6 5.87 186.8
If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl3(g) ?

Accepted Answer

A)   -18.2 J/K·mol
B)   18.2 J/K·mol
C)   290.1 J/K·mol
D)   355.4 J/K.mol
E)   450.6 J/K·molF) D) and E)
G) B) and D)

Question 8

Sulfuryl dichloride is formed when sulfur dioxide reacts with chlorine. The data refer to 298 K. SO2(g)  + Cl2(g)  → SO2Cl2(g) 
Substance: SO2(g)  Cl2(g)  SO2Cl2(g) 
ΔH°f (kJ/mol) : -296.8 0 -364.0
ΔG°f (kJ/mol) : -300.1 0 -320.0
S°(J/K·mol) : 248.2 223.0 311.9
What is the value of ΔG° for this reaction at 600 K?

Accepted Answer

A)   -162.8 kJ
B)   -40.1 kJ
C)   -28.4 kJ
D)   28.4 kJ
E)   162.8 kJF) B) and D)
G) A) and E)

Question 9

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

Accepted Answer

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

Question 10

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH4(g)  + 2H2O(g)  4(g)  + 2H2O(g)    CO2(g)  + 4H2(g)    A)  658 K B)  683 K C)  955 K D)  1047 K E)  1229 K" class="answers-bank-image d-inline" rel="preload" > CO2(g)  + 4H2(g) 
4(g)  + 2H2O(g)    CO2(g)  + 4H2(g)    A)  658 K B)  683 K C)  955 K D)  1047 K E)  1229 K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   658 K
B)   683 K
C)   955 K
D)   1047 K
E)   1229 KF) C) and E)
G) C) and D) C

Question 11

You are given pure samples of ammonia, NH3(g) , and nitrogen trifluoride, NF3(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

A)   S°ammonia > S°nitrogen trifluoride
B)   S°ammonia nitrogen trifluoride
C)   S°ammonia ≈ S°nitrogen trifluoride
D)   Other conditions need to be specified before a reliable prediction can be made.
E)   Even if more conditions are specified, a reliable prediction cannot be made.F) B) and D)
G) A) and C)

Question 12

In order for a process to be spontaneous,

Accepted Answer

A)   ΔH must be less than zero.
B)   ΔS must be greater than zero.
C)   ΔG must be greater than zero.
D)   it should be rapid.
E)   ΔSsys + ΔSsurr must be greater than zero.F) B) and E)
G) B) and D)

Question 13

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

Accepted Answer

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

Question 14

A reaction has ΔG = 10.0 kJ and ΔG° = 15.0 kJ at a temperature of 50°C. Calculate the value of the reaction quotient Q under these conditions.

Accepted Answer

A)   0.16
B)   9.1 × 10-5
C)   1.1 × 104
D)   6.4
E)   6.0 × 10-6F) C) and D)
G) D) and E)

Question 15

Calculate ΔG° for the combustion of propane. C3H8(g)  + 5O2(g)  → 3CO2(g)  + 4H2O(g) 
Substance: C3H8(g)  O2(g)  CO2(g)  H2O(g) 
ΔG°f (kJ/mol) : -24.5 0 -394.4 -228.6

Accepted Answer

A)   -2073.1 kJ
B)   -1387.3 kJ
C)   -598.5 kJ
D)   598.5 kJ
E)   2073.1 kJF) A) and B)
G) C) and E)

Question 16

In order for a process to be spontaneous,

Accepted Answer

A)   the entropy of the system must increase.
B)   the entropy of the surroundings must increase.
C)   the entropy of the universe must decrease.
D)   the entropy of the surroundings must decrease.
E)   the entropy change of the surroundings plus the entropy change of the system must be positive.F) A) and D)
G) All of the above

Question 17

As a chemical reaction proceeds toward equilibrium, the free energy of the system decreases.

Accepted Answer

A) True 
 B)False

Question 18

Which relationship or statement best describes ΔS° for the following reaction? C2H5OH(l)  + 3O2(g)  → 2CO2(g)  + 3H2O(l)

Accepted Answer

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

Question 19

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

Accepted Answer

A) True 
 B)False

Question 20

Iron(III)  oxide can be reduced by carbon monoxide. Fe2O3(s)  + 3CO(g)  2O3(s)  + 3CO(g)    2Fe(s)  + 3CO2(g)  Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.   A)  7.0 × 10-6 B)  1.3 × 10-3 C)  2.2 × 104 D)  1.4 × 105 E)  > 2.0 × 105" class="answers-bank-image d-inline" rel="preload" > 2Fe(s)  + 3CO2(g) 
Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.
2O3(s)  + 3CO(g)    2Fe(s)  + 3CO2(g)  Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.   A)  7.0 × 10-6 B)  1.3 × 10-3 C)  2.2 × 104 D)  1.4 × 105 E)  > 2.0 × 105" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   7.0 × 10-6
B)   1.3 × 10-3
C)   2.2 × 104
D)   1.4 × 105
E)   > 2.0 × 105F) B) and E)
G) A) and E)

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

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. H₃PO₄(s) H₃PO₄(l) Use the following thermodynamic information at 298 K to determine this temperature.

Correct Answer
verified

Which of the following should have the greatest molar entropy at 298 K?

Correct Answer
verified
D

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

Correct Answer
verified

Which relationship or statement best describes ΔS° for the following reaction? 2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

Correct Answer
verified
C

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

Correct Answer
verified

Given: H₂O(l) → H₂O(s) ΔH° = -6.02 kJ at 273K Calculate the entropy change of the surroundings (ΔS_surr) when one mole of water freezes at 0°C and a pressure of one atmosphere.

Correct Answer
verified

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl₃(g) + 1.5H₂(g) → B(s) + 3HCl(g) Substance: BCl₃(g) H₂(g) B(s) HCl(g) S°(J/K·mol) : ? 130.6 5.87 186.8 If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl₃(g) ?

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH₄(g) + 2H₂O(g) CO₂(g) + 4H₂(g)

Correct Answer
verified
C

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

In order for a process to be spontaneous,

Correct Answer
verified

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

Correct Answer
verified

A reaction has ΔG = 10.0 kJ and ΔG° = 15.0 kJ at a temperature of 50°C. Calculate the value of the reaction quotient Q under these conditions.

Correct Answer
verified

Calculate ΔG° for the combustion of propane. C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g) Substance: C₃H₈(g) O₂(g) CO₂(g) H₂O(g) ΔG°_f (kJ/mol) : -24.5 0 -394.4 -228.6

Correct Answer
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In order for a process to be spontaneous,

Correct Answer
verified

As a chemical reaction proceeds toward equilibrium, the free energy of the system decreases.

Correct Answer
verified

Which relationship or statement best describes ΔS° for the following reaction? C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

Correct Answer
verified

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

Correct Answer
verified

Iron(III) oxide can be reduced by carbon monoxide. Fe₂O₃(s) + 3CO(g) 2Fe(s) + 3CO₂(g) Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

Correct Answer
verified

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

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. H3PO4(s) H3PO4(l) Use the following thermodynamic information at 298 K to determine this temperature.

Correct AnswerverifiedShow Answer

Which of the following should have the greatest molar entropy at 298 K?

Correct AnswerverifiedD

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

Correct AnswerverifiedShow Answer

Which relationship or statement best describes ΔS° for the following reaction? 2NH3(g) + 2ClF3(g) → 6HF(g) + N2(g) + Cl2(g)

Correct AnswerverifiedC

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

Correct AnswerverifiedShow Answer

Given: H2O(l) → H2O(s) ΔH° = -6.02 kJ at 273K Calculate the entropy change of the surroundings (ΔSsurr) when one mole of water freezes at 0°C and a pressure of one atmosphere.

Correct AnswerverifiedShow Answer

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl3(g) + 1.5H2(g) → B(s) + 3HCl(g) Substance: BCl3(g) H2(g) B(s) HCl(g) S°(J/K·mol) : ? 130.6 5.87 186.8 If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl3(g) ?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH4(g) + 2H2O(g) CO2(g) + 4H2(g)

Correct AnswerverifiedC

You are given pure samples of ammonia, NH3(g) , and nitrogen trifluoride, NF3(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct AnswerverifiedShow Answer

In order for a process to be spontaneous,

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A reaction has ΔG = 10.0 kJ and ΔG° = 15.0 kJ at a temperature of 50°C. Calculate the value of the reaction quotient Q under these conditions.

Correct AnswerverifiedShow Answer

Calculate ΔG° for the combustion of propane. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) Substance: C3H8(g) O2(g) CO2(g) H2O(g) ΔG°f (kJ/mol) : -24.5 0 -394.4 -228.6

Correct AnswerverifiedShow Answer

In order for a process to be spontaneous,

Correct AnswerverifiedShow Answer

As a chemical reaction proceeds toward equilibrium, the free energy of the system decreases.

Correct AnswerverifiedShow Answer

Which relationship or statement best describes ΔS° for the following reaction? C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Iron(III) oxide can be reduced by carbon monoxide. Fe2O3(s) + 3CO(g) 2Fe(s) + 3CO2(g) Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

Correct AnswerverifiedShow Answer

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. H₃PO₄(s) H₃PO₄(l) Use the following thermodynamic information at 298 K to determine this temperature.

Correct Answer
verified

Correct Answer
verified
D

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

Correct Answer
verified

Which relationship or statement best describes ΔS° for the following reaction? 2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

Correct Answer
verified
C

Correct Answer
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Given: H₂O(l) → H₂O(s) ΔH° = -6.02 kJ at 273K Calculate the entropy change of the surroundings (ΔS_surr) when one mole of water freezes at 0°C and a pressure of one atmosphere.

Correct Answer
verified

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl₃(g) + 1.5H₂(g) → B(s) + 3HCl(g) Substance: BCl₃(g) H₂(g) B(s) HCl(g) S°(J/K·mol) : ? 130.6 5.87 186.8 If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl₃(g) ?

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH₄(g) + 2H₂O(g) CO₂(g) + 4H₂(g)

Correct Answer
verified
C

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
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Calculate ΔG° for the combustion of propane. C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g) Substance: C₃H₈(g) O₂(g) CO₂(g) H₂O(g) ΔG°_f (kJ/mol) : -24.5 0 -394.4 -228.6

Correct Answer
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Correct Answer
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Correct Answer
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Which relationship or statement best describes ΔS° for the following reaction? C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

Correct Answer
verified

Correct Answer
verified

Iron(III) oxide can be reduced by carbon monoxide. Fe₂O₃(s) + 3CO(g) 2Fe(s) + 3CO₂(g) Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

Correct Answer
verified