Question 1

A chemical reaction has F1F1F1S1F1F1F10G° = 10.0 kJ and F1F1F1S1F1F1F10S° = 50.0 J/K
a. Calculate F1F1F1S1F1F1F10H° for this reaction at 25°C.
b. Could this reaction ever be spontaneous? Explain your answer.

Accepted Answer

a. H° = 24.9 kJ
b. Yes. ...

Question 2

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. 
Use the following thermodynamic data at 298 K to determine this temperature.

Accepted Answer

A)   286 K
B)   305 K
C)   315 K
D)   347 K
E)   3170 KF) A) and E)
G) None of the above

Question 3

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

Accepted Answer

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

Question 4

Calculate S° for the reaction S° for the reaction   A)  -548.1 J/K B)  -147.7 J/K C)  147.7 J/K D)  310.1 J/K E )  548.1 J/K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -548.1 J/K
B)   -147.7 J/K
C)   147.7 J/K
D)   310.1 J/K E )  548.1 J/KE) All of the above
F) A) and B)

Question 5

Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

Accepted Answer

A)   .H > 0
B)   .H 
C)   .Ssys > 0
D)   .Ssurr > Ssys
E)   .S > H/TF) A) and E)
G) All of the above

Question 6

The second law of thermodynamics tells us that

Accepted Answer

A)   the entropy of the universe is constant.
B)   entropy is neither created nor destroyed.
C)   the universe proceeds toward a state of lower entropy.
D)   the universe proceeds toward a state of higher entropy.
E)   the universe cannot create entropy.F) All of the above
G) A) and D)

Question 7

A reaction has G = 10.0 kJ and G° = 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) A) and B)
G) A) and C)

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

Hydrogen sulfide decomposes according to the following reaction 
2H2S(g)   2H2(g)  + S2(g) 
For this reaction at 298K S°  = 78.1 J/K, H°  = 169.4 kJ, and G° = 146.1 kJ. What is the value of G° at 900 K?

Accepted Answer

A)   -69881 kJ
B)   48.4 kJ
C)   99.1 kJ
D)   240 kJ
E)   441 kJF) A) and B)
G) A) and C)

Question 11

A sample of water is heated at a constant pressure of one atmosphere. Initially, the sample is ice at 260 K, and at the end the sample consists of steam at 400 K. In which of the following 5K temperature intervals would there be the greatest increase in the entropy of the sample?

Accepted Answer

A)   from 260 K to 265 K
B)   from 275 K to 280 K
C)   from 360 K to 365 K
D)   370 K to 375 K
E)   from 395 K to 400 KF) A) and B)
G) All of the above

Question 12

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

Accepted Answer

A)   .S° > 0, H° > 0
B)   .S° > 0, H° 
C)   .S° H° 
D)   .S° H° > 0
E)   All reactions are spontaneous at some temperature.F) None of the above
G) C) and D)

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide.

Use the following thermodynamic information at 298 K to determine this temperature.

Accepted Answer

A)   120°C
B)   144°C
C)   196°C
D)   418°C
E)   585°CF) C) and E)
G) B) and D)

Question 15

You are given pure samples of pentane, CH3CH2CH2CH2CH3(l) , and 1,3-pentadiene, CH2=CHCH=CHCH3(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

A)   S°pentane > S°1, 3-pentadiene
B)   S°pentane 1, 3-pentadiene
C)   S°pentane  S°1, 3-pentadiene
D)   S°pentane = S°1, 3-pentadiene + 2 3CH2CH2CH2CH3(l) , and 1,3-pentadiene, CH2=CHCH=CHCH3(l) . What prediction would you make concerning their standard molar entropies at 298 K? 
A)   S°pentane > S°1, 3-pentadiene 
B)   S°pentane 1, 3-pentadiene 
C)   S°pentane  S°1, 3-pentadiene 
D)   S°pentane = S°1, 3-pentadiene + 2   
E)   More information is needed to make reasonable predictions." class="answers-bank-image d-inline" rel="preload" >
E)   More information is needed to make reasonable predictions.F) B) and E)
G) A) and B)

Question 16

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

Accepted Answer

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

Question 17

What is the free energy change, G°, for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453°C? 
G°, for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453°C?    A)  6.4 kJ B)  8.8 kJ C)  15 kJ D)  19 kJ E)  24 kJ" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   6.4 kJ
B)   8.8 kJ
C)   15 kJ
D)   19 kJ
E)   24 kJF) A) and B)
G) A) and C)

Question 18

In tables of thermodynamic data provided in chemistry books, one finds F1F1F1S1F1F1F10H°f, F1F1F1S1F1F1F10G°f, and S° listed. Briefly, explain why the entropy data are supplied as S°, while the enthalpy and free energy data are in the form of F1F1F1S1F1F1F10H°f and F1F1F1S1F1F1F10G°f, respectively.

Accepted Answer

The third law specifies the state of zer...

Question 19

Calculate G° for the combustion of propane. G° for the combustion of propane.   A)  -2073.1 kJ B)  -1387.3 kJ C)  -598.5 kJ D)  598.5 kJ E)  2073.1 kJ" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

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

Question 20

Calculate G° for the reaction G° for the reaction   A)  566.60 kJ B)  50.38 kJ C)  25.19 kJ D)  -25.19 kJ E)  -566.60 kJ" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   566.60 kJ
B)   50.38 kJ
C)   25.19 kJ
D)   -25.19 kJ
E)   -566.60 kJF) A) and B)
G) D) and E)

Exam 20: Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide. Use the following thermodynamic information at 298 K to determine this temperature.

Correct AnswerverifiedShow Answer

A sample of water is heated at a constant pressure of one atmosphere. Initially, the sample is ice at 260 K, and at the end the sample consists of steam at 400 K. In which of the following 5K temperature intervals would there be the greatest increase in the entropy of the sample?

Correct AnswerverifiedShow Answer

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid. Use the following thermodynamic data at 298 K to determine this temperature.

Correct AnswerverifiedShow Answer

What is the free energy change, G°, for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453°C?

Correct AnswerverifiedShow Answer

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

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

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A chemical reaction has G° = 10.0 kJ and S° = 50.0 J/K a. Calculate H° for this reaction at 25°C. b. Could this reaction ever be spontaneous? Explain your answer.

Correct Answerverifieda. H° = 24.9 kJb. Yes. ...View AnswerShow Answer

Hydrogen sulfide decomposes according to the following reaction 2H2S(g)  2H2(g) + S2(g) For this reaction at 298K S° = 78.1 J/K, H° = 169.4 kJ, and G° = 146.1 kJ. What is the value of G° at 900 K?

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

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

Correct AnswerverifiedShow Answer

Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

Correct AnswerverifiedShow Answer

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

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Calculate G° for the combustion of propane.

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

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Calculate S° for the reaction

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In tables of thermodynamic data provided in chemistry books, one finds H°f, G°f, and S° listed. Briefly, explain why the entropy data are supplied as S°, while the enthalpy and free energy data are in the form of H°f and G°f, respectively.

Correct AnswerverifiedThe third law specifies the state of zer...View AnswerShow Answer

You are given pure samples of pentane, CH3CH2CH2CH2CH3(l) , and 1,3-pentadiene, CH2=CHCH=CHCH3(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct AnswerverifiedShow Answer

The second law of thermodynamics tells us that

Correct AnswerverifiedShow Answer

Calculate G° for the reaction

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

Correct AnswerverifiedShow Answer

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

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

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A chemical reaction has G° = 10.0 kJ and S° = 50.0 J/K a. Calculate H°for this reaction at 25°C. b. Could this reaction ever be spontaneous? Explain your answer.

Correct Answer
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a. H° = 24.9 kJ
b. Yes. ...
View Answer

Hydrogen sulfide decomposes according to the following reaction 2H₂S(g)  2H₂(g) + S₂(g) For this reaction at 298K S°= 78.1 J/K, H°= 169.4 kJ, and G° = 146.1 kJ. What is the value of G° at 900 K?

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

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Calculate G°for the combustion of propane.

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

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Correct Answer
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In tables of thermodynamic data provided in chemistry books, one finds H°_f, G°_f, and S° listed. Briefly, explain why the entropy data are supplied as S°, while the enthalpy and free energy data are in the form of H°_f and G°_f, respectively.

Correct Answer
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The third law specifies the state of zer...
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You are given pure samples of pentane, CH₃CH₂CH₂CH₂CH₃(l) , and 1,3-pentadiene, CH₂=CHCH=CHCH₃(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Correct Answer
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Correct Answer
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Calculate G°for the reaction

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Correct Answer
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