Question 1

Which relationship or statement best describes S° for the following reaction? 
KCl(s)   K+(aq)  + Cl-(aq)

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) All of the above
G) None of the above

Question 2

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 E)
G) C) and D)

Question 3

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

Question 4

Given: C2H2(g) F1F1F1S1F1F1F10 2C(graphite) + H2(g) F1F1F1S1F1F1F10G° = -209 kJ
A sample of gaseous C2H2 (acetylene, or ethyne) was stored for one year, yet at the end of this period the sample remained unchanged and no graphite or hydrogen gas had been formed. Briefly explain why there is no inconsistency between the sign of F1F1F1S1F1F1F10G° and the apparent stability of the sample.

Accepted Answer

Relative to graphite and hydrogen, acety...

Question 5

Which of the following is always true for an endothermic process?

Accepted Answer

A)   q sys > 0, Ssurr 
B)   q sys Ssurr > 0
C)   q sys Ssurr 
D)   q sys > 0, Ssurr > 0
E)   w < 0F) A) and E)
G) A) and D)

Question 6

Which of the following is true for a system at equilibrium?

Accepted Answer

A)   .S°sys = S°surr
B)   .S°sys = -S°surr
C)   .S°sys = S°surr = 0
D)   .S°univ > 0
E)   None of the above is a sufficient condition.F) A) and B)
G) B) and D)

Question 7

For a reaction at equilibrium, F1F1F1S1F1F1F10Suniv = 0.

Accepted Answer

A) True 
 B)False

Question 8

A reaction has a positive value of F1F1F1S1F1F1F10H° and a positive value of F1F1F1S1F1F1F10S°.
Draw a neat, labeled schematic plot to show how F1F1F1S1F1F1F10G° (y-axis) will depend on absolute temperature (x-axis).

Accepted Answer

The answer of A reaction has a positive value of...

Question 9

For a chemical reaction to be spontaneous at all temperatures, 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)   It is not possible for a reaction to be spontaneous at all temperatures.F) A) and E)
G) B) and E)

Question 10

Which of the following values is based on the Third Law of Thermodynamics?

Accepted Answer

A)   .H° f = 0 for Al(s)  at 298 K
B)   .G° f = 0 for H2(g)  at 298 K
C)   S° = 51.446 J/(mol·K)  for Na(s)  at 298 K
D)   q sys 2O(l)   H2O(s)  at 0°C
E)   none of the aboveF) C) and D)
G) A) and B)

Question 11

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K. G° for this reaction at 550 K? A)  -143.76 kJ B)  -78.78 kJ C)  -22.24 kJ D)  -10.56 kJ E)  66600 kJ" class="answers-bank-image d-inline" rel="preload" > What is the value of G° 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 E)
G) A) and B)

Question 12

Calculate S° for the combustion of propane. S° for the combustion of propane.   A)  -100.9 J/K B)  -72.5 J/K C)  72.5 J/K D)  100.9 J/K E)  877.5 J/K" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -100.9 J/K
B)   -72.5 J/K
C)   72.5 J/K
D)   100.9 J/K
E)   877.5 J/KF) A) and D)
G) None of the above

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

Which, if any, of the following processes is spontaneous under the specified conditions?

Accepted Answer

A)   H2O(l)   H2O(s)  at 25°C
B)   CO2(s)   CO2(g)  at 0°C
C)   2H2O(g)   2H2(g)  + O2(g) 
D)   C(graphite)   C(diamond)  at 25°C and 1 atm pressure
E)   None of the above is spontaneous.F) All of the above
G) A) and D)

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

Which of the following is always true for an endothermic process?

Correct Answer
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Calculate S° for the combustion of propane.

Correct Answer
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For a reaction at equilibrium, S_univ = 0.

Correct Answer
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Which of the following is true for a system at equilibrium?

Correct Answer
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A reaction has a positive value of H° and a positive value of S°. Draw a neat, labeled schematic plot to show how G° (y-axis) will depend on absolute temperature (x-axis).

Correct Answer
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Correct Answer
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Relative to graphite and hydrogen, acety...
View Answer

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

Correct Answer
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Which, if any, of the following processes is spontaneous under the specified conditions?

Correct Answer
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Which of the following values is based on the Third Law of Thermodynamics?

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

Correct Answer
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Which relationship or statement best describes S° for the following reaction? KCl(s)  K⁺(aq) + Cl^-(aq)

Correct Answer
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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

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

Correct Answer
verified

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K. What is the value of G° for this reaction at 550 K?

Correct Answer
verified

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

Which of the following is always true for an endothermic process?

Correct AnswerverifiedShow Answer

Calculate S° for the combustion of propane.

Correct AnswerverifiedShow Answer

For a reaction at equilibrium, Suniv = 0.

Correct AnswerverifiedShow Answer

Which of the following is true for a system at equilibrium?

Correct AnswerverifiedShow Answer

A reaction has a positive value of H° and a positive value of S°. Draw a neat, labeled schematic plot to show how G° (y-axis) will depend on absolute temperature (x-axis).

Correct AnswerverifiedShow Answer

Correct AnswerverifiedRelative to graphite and hydrogen, acety...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

Which, if any, of the following processes is spontaneous under the specified conditions?

Correct AnswerverifiedShow Answer

Which of the following values is based on the Third Law of Thermodynamics?

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 S° for the following reaction? KCl(s)  K+(aq) + Cl-(aq)

Correct AnswerverifiedShow Answer

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

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

Correct AnswerverifiedShow Answer

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K. What is the value of G° for this reaction at 550 K?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

For a reaction at equilibrium, S_univ = 0.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Relative to graphite and hydrogen, acety...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Which relationship or statement best describes S° for the following reaction? KCl(s)  K⁺(aq) + Cl^-(aq)

Correct Answer
verified

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

Correct Answer
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