Question 1

Calculate the equilibrium constant at 25°C for the reaction of methane with water to form carbon dioxide and hydrogen. The data refer to 
19 B)  0.96 C)  0.58 D)  1.2 × 10-20 E)  1.4 × 10-46" class="answers-bank-image d-inline" rel="preload" >
19 B)  0.96 C)  0.58 D)  1.2 × 10-20 E)  1.4 × 10-46" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   8.2 × 1019
B)   0.96
C)   0.58
D)   1.2 × 10-20
E)   1.4 × 10-46F) All of the above
G) A) and D)

Question 2

Consider the following quantities used in thermodynamics: E, H, q, w, S, G. How many of them are state functions?

Accepted Answer

A)   0
B)   1
C)   2
D)   3
E)   4F) A) and C)
G) A) and E)

Question 3

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

Accepted Answer

A) True 
 B)False

Question 4

When a sky diver free-falls through the air, the process is

Accepted Answer

A)   non-spontaneous because he is accelerating due to the force applied by gravity.
B)   non-spontaneous because he is losing potential energy.
C)   non-spontaneous, if he had planned the jump for two weeks.
D)   spontaneous.
E)   in equilibrium.F) A) and B)
G) B) and E)

Question 5

Which relationship or statement best describes S° for the following reaction? 
2H2S(g)  + 3O2(g)   2H2O(g)  + 2SO2(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 E)
G) A) and D)

Question 6

Which of the following is always true for an exothermic 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) None of the above
G) C) and D)

Question 7

The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

Accepted Answer

A) True 
 B)False

Question 8

For the reaction of xenon and fluorine gases to form solid XeF4, F1F1F1S1F1F1F10H° = -251 kJ and F1F1F1S1F1F1F10G° = -121 kJ at 25°C. Calculate F1F1F1S1F1F1F10S° for the reaction.

Accepted Answer

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Question 9

In some spontaneous processes, the entropy of the surroundings decreases.

Accepted Answer

A) True 
 B)False

Question 10

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 O2(g) ; 2 mole O(g) 
C)   1 mole CH4(g) ; 1 mole C2H6(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) A) and C)

Question 11

Which relationship or statement best describes S° for the following reaction? 
O3(g)  + NO(g)   O2(g)  + NO2(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) C) and D)
G) A) and C)

Question 12

A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that G = G°. 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) None of the above
G) C) and D)

Question 13

For a process with S < 0, which one of the following statements is correct?

Accepted Answer

A)   The process will definitely be spontaneous if H 
B)   The process will be definitely be spontaneous if H S.
C)   The process can never be spontaneous.
D)   The process will definitely be spontaneous, regardless of H.
E)   The process will definitely be spontaneous if Ssurr > 0.F) C) and D)
G) B) and D)

Question 14

The term microstate refers to the energy state of a single molecule in a system of many molecules.

Accepted Answer

A) True 
 B)False

Question 15

"A diamond is forever" is one of the most successful advertising slogans of all time. But is it true? For the reaction shown below, calculate the standard free energy change at 298K and determine whether or not a diamond is "forever". C(diamond)   C(graphite) 
Data: Hf°(diamond)  = 1.895 kJ/mol; S°(diamond)  = 2.337 J mol-1 K-1;
S°(graphite)  = 5.740 J mol-1K-1.

Accepted Answer

A)   .G° = 2.19 kJ; forever
B)   .G° = -1.90 kJ; not forever
C)   .G° = -2.90 kJ; not forever
D)   .G° = 1.90 kJ; forever
E)   .G° = < -1000 kJ; not foreverF) None of the above
G) All of the above

Question 16

In a spontaneous process, the entropy of the system always increases.

Accepted Answer

A) True 
 B)False

Question 17

Which one of the following phase changes decreases the entropy of the system?

Accepted Answer

A)   melting
B)   heating a gas
C)   vaporization
D)   condensation
E)   sublimationF) A) and D)
G) C) and E)

Question 18

Which of the following results in a decrease in the entropy of the system?

Accepted Answer

A)   O2(g) , 300 K  O2(g) , 400 K
B)   H2O(s) , 0°C  H2O(l) , 0°C
C)   N2(g) , 25°C  N2(aq) , 25°C
D)   NH3(l) , -34.5°C  NH3(g) , -34.5°C
E)   2H2O2(g)   2H2O(g)  + O2(g) F) B) and C)
G) A) and E)

Question 19

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Accepted Answer

A)   CO(g) , CO2(g) 
B)   NaCl(s) , NaCl(aq) 
C)   H2S(g) , H2S(aq) 
D)   Li(s) , Pb(s) 
E)   H2(g) , H2O(g) F) B) and D)
G) A) and D)

Question 20

A certain process has Suniv > 0 at 25°C. What does one know about the process?

Accepted Answer

A)   It is exothermic.
B)   It is endothermic.
C)   It is spontaneous at 25°C.
D)   It will move rapidly toward equilibrium.
E)   none of the aboveF) A) and E)
G) B) and D)

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

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.

Correct Answer
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Consider the following quantities used in thermodynamics: E, H, q, w, S, G. How many of them are state functions?

Correct Answer
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For the reaction of xenon and fluorine gases to form solid XeF₄, H° = -251 kJ and G° = -121 kJ at 25°C. Calculate S° for the reaction.

Correct Answer
verified
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View Answer

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

Correct Answer
verified

The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

Correct Answer
verified

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

Correct Answer
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The term microstate refers to the energy state of a single molecule in a system of many molecules.

Correct Answer
verified

When a sky diver free-falls through the air, the process is

Correct Answer
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Correct Answer
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Which one of the following phase changes decreases the entropy of the system?

Correct Answer
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For a process with S < 0, which one of the following statements is correct?

Correct Answer
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Calculate the equilibrium constant at 25°C for the reaction of methane with water to form carbon dioxide and hydrogen. The data refer to

Correct Answer
verified

Which of the following results in a decrease in the entropy of the system?

Correct Answer
verified

A certain process has S_univ > 0 at 25°C. What does one know about the process?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
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Which of the following is always true for an exothermic process?

Correct Answer
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In a spontaneous process, the entropy of the system always increases.

Correct Answer
verified

In some spontaneous processes, the entropy of the surroundings decreases.

Correct Answer
verified

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Correct Answer
verified

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

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.

Correct AnswerverifiedShow Answer

Consider the following quantities used in thermodynamics: E, H, q, w, S, G. How many of them are state functions?

Correct AnswerverifiedShow Answer

For the reaction of xenon and fluorine gases to form solid XeF4, H° = -251 kJ and G° = -121 kJ at 25°C. Calculate S° for the reaction.

Correct AnswerverifiedF...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The term microstate refers to the energy state of a single molecule in a system of many molecules.

Correct AnswerverifiedShow Answer

When a sky diver free-falls through the air, the process is

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which one of the following phase changes decreases the entropy of the system?

Correct AnswerverifiedShow Answer

For a process with S < 0, which one of the following statements is correct?

Correct AnswerverifiedShow Answer

Calculate the equilibrium constant at 25°C for the reaction of methane with water to form carbon dioxide and hydrogen. The data refer to

Correct AnswerverifiedShow Answer

Which of the following results in a decrease in the entropy of the system?

Correct AnswerverifiedShow Answer

A certain process has Suniv > 0 at 25°C. What does one know about the process?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

In a spontaneous process, the entropy of the system always increases.

Correct AnswerverifiedShow Answer

In some spontaneous processes, the entropy of the surroundings decreases.

Correct AnswerverifiedShow Answer

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
verified

For the reaction of xenon and fluorine gases to form solid XeF₄, H° = -251 kJ and G° = -121 kJ at 25°C. Calculate S° for the reaction.

Correct Answer
verified
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View Answer

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

Correct Answer
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A certain process has S_univ > 0 at 25°C. What does one know about the process?

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

Correct Answer
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