Question 1

What is the change in entropy for the vaporization of 18 g of H2O at 100°C? At this temperature, the molar enthalpy of vaporization for water is 44.0 kJ/mol.

Accepted Answer

A)   44 kJ/mol
B)   440 J/K
C)   117.9 J/K
D)   -41 kJ/K
E)   -440 kJ/KF) B) and E)
G) A) and D)

Question 2

Predict the sign of ΔS for the reaction O2(g) → 2O(g).

Accepted Answer

Question 3

Which is the thermodynamic condition for a spontaneous process at constant T and P?

Accepted Answer

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

Question 4

Which has the largest entropy?

Accepted Answer

A)   C (diamond) 
B)   C (graphite) 
C)   H2O(l) 
D)   F2(l) 
E)   O2(g) F) All of the above
G) A) and E)

Question 5

If a certain process has ΔSuniv > 0 at 25°C, the process may be described as

Accepted Answer

A)   exothermic.
B)   endothermic.
C)   spontaneous.
D)   moving rapidly toward equilibrium.
E)   violating the second law of thermodynamics.F) C) and D)
G) B) and E)

Question 6

A negative sign for ΔG indicates that, at constant T and P,

Accepted Answer

A)   the reaction is exothermic.
B)   the reaction is endothermic.
C)   the reaction is fast.
D)   the reaction is spontaneous.
E)   ΔS of the system must be greater than zero.F) A) and D)
G) A) and C)

Question 7

Below are energy level diagrams for two different atoms.  Based on the diagrams, which atom has the larger standard molar entropy at T = 298 K?

Accepted Answer

A)   Atom 1 has the larger standard molar entropy because the energy of its ground state is larger than the energy of the ground state of atom 2.
B)   Atom 2 has the larger standard molar entropy because the energy of its ground state is smaller than the energy of the ground state of atom 1.
C)   Atom 1 has the larger standard molar entropy because it has fewer energy levels at lower energy values than atom 2.
D)   Atom 2 has the larger standard molar entropy because it has more energy levels at lower energy values than atom 1.
E)   Both atoms have the same value of the standard molar entropy at T = 298 K.F) B) and C)
G) B) and E)

Question 8

Which is a statement of the second law of thermodynamics?

Accepted Answer

A)   The energy of the universe is constant.
B)   The entropy of the universe is constant.
C)   The enthalpy of the universe is constant.
D)   The energy of the universe is decreasing.
E)   The entropy of the universe is increasing.F) B) and C)
G) A) and E)

Question 9

Which statement is correct?

Accepted Answer

A)   The standard entropy of a gas phase substance is less than the standard entropy of the same substance in the solid phase.
B)   For two different substances in the same phase, the substance with the more complex structure has the lower entropy.
C)   The more highly ordered allotrope of an element has a higher entropy.
D)   The entropies of elements and compounds are always positive.
E)   For a monatomic gas, the gas with the lower molar mass has the greater entropy.F) B) and C)
G) A) and E)

Question 10

Nitric oxide reacts with chlorine to form NOCl. 2NO(g)  + Cl2(g)  → 2NOCl(g)  2(g)  → 2NOCl(g)    What is ΔG°rxn for this reaction at 550. K? A)  -143.76 kJ/mol B)  -78.78 kJ/mol C)  -22.24 kJ/mol D)  -10.6 kJ/mol E)  66600 kJ/mol" class="answers-bank-image d-inline" rel="preload" > What is ΔG°rxn for this reaction at 550. K?

Accepted Answer

A)   -143.76 kJ/mol
B)   -78.78 kJ/mol
C)   -22.24 kJ/mol
D)   -10.6 kJ/mol
E)   66600 kJ/molF) All of the above
G) B) and D)

Question 11

How many types of rotations does a bent triatomic molecule exhibit?

Accepted Answer

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

Question 12

Which reaction has the largest ΔS°?

Accepted Answer

A)   2N2H4(g)  → 2NH3(g)  + H2(g)  + N2(g) 
B)   O2(g)  + 2H2(g)  → 2H2O(l) 
C)   O2(g)  + 2H2(g)  → 2H2O(g) 
D)   N2(g)  + 3H2(g)  → 2NH3(g) 
E)   2NO(g)  → N2O2(g) F) B) and E)
G) A) and E)

Question 13

A spontaneous endothermic reaction always

Accepted Answer

A)   causes the surroundings to get colder.
B)   bursts into flame.
C)   requires a spark to initiate it.
D)   releases heat to the surroundings.E) A) and B)
F) A) and C)

Question 14

How many types of rotations does a diatomic molecule exhibit?

Accepted Answer

A)   0
B)   1
C)   2
D)   3
E)   4F) B) and E)
G) None of the above

Question 15

For a given reaction, a change in the temperature may result in a change in the sign of ΔG.

Accepted Answer

A) True 
 B)False

Question 16

Which is a statement of the third law of thermodynamics?

Accepted Answer

A)   The entropy of the universe is increasing.
B)   The entropy of the universe is constant.
C)   For a perfect crystalline solid, the entropy at T = 0 K is zero.
D)   The energy of the universe is constant.
E)   The entropy of all elements are zero.F) D) and E)
G) A) and E)

Question 17

For the following process, which is true?  0, ΔS > 0 B)  ΔH > 0, ΔS  0 D)  ΔH  0, ΔS = 0" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

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

Question 18

All elements in their standard state have standard entropies of formation equal to zero.

Accepted Answer

A) True 
 B)False

Question 19

ΔSuniverse > 0 is the general condition for a ________ process.

Accepted Answer

Question 20

What is ΔS° at 298 K for the following reaction? Fe2O3(s)  + 3CO(g)  → 3CO2(g)  + 2Fe(s)  2O3(s)  + 3CO(g)  → 3CO2(g)  + 2Fe(s)    A)  12.7 J/K • mol B)  -12.7 J/K • mol C)  527.9 J/K • mol D)  157.2 J/K • mol E)  4.6 J/K • mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   12.7 J/K • mol
B)   -12.7 J/K • mol
C)   527.9 J/K • mol
D)   157.2 J/K • mol
E)   4.6 J/K • molF) C) and E)
G) C) and D)

Exam 18: Entropy, Free Energy, and Equilibrium

What is the change in entropy for the vaporization of 18 g of H2O at 100°C? At this temperature, the molar enthalpy of vaporization for water is 44.0 kJ/mol.

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How many types of rotations does a diatomic molecule exhibit?

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Below are energy level diagrams for two different atoms. Based on the diagrams, which atom has the larger standard molar entropy at T = 298 K?

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Which is a statement of the second law of thermodynamics?

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Nitric oxide reacts with chlorine to form NOCl. 2NO(g) + Cl2(g) → 2NOCl(g) What is ΔG°rxn for this reaction at 550. K?

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Which reaction has the largest ΔS°?

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For the following process, which is true?

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If a certain process has ΔSuniv > 0 at 25°C, the process may be described as

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Which is a statement of the third law of thermodynamics?

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ΔSuniverse > 0 is the general condition for a ________ process.

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A spontaneous endothermic reaction always

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What is ΔS° at 298 K for the following reaction? Fe2O3(s) + 3CO(g) → 3CO2(g) + 2Fe(s)

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A negative sign for ΔG indicates that, at constant T and P,

Correct AnswerverifiedShow Answer

Predict the sign of ΔS for the reaction O2(g) → 2O(g).

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Which has the largest entropy?

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Which statement is correct?

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For a given reaction, a change in the temperature may result in a change in the sign of ΔG.

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Which is the thermodynamic condition for a spontaneous process at constant T and P?

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All elements in their standard state have standard entropies of formation equal to zero.

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How many types of rotations does a bent triatomic molecule exhibit?

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What is the change in entropy for the vaporization of 18 g of H₂O at 100°C? At this temperature, the molar enthalpy of vaporization for water is 44.0 kJ/mol.

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Nitric oxide reacts with chlorine to form NOCl. 2NO(g) + Cl₂(g) → 2NOCl(g) What is ΔG°_rxn for this reaction at 550. K?

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If a certain process has ΔS_univ> 0 at 25°C, the process may be described as

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ΔS_universe > 0 is the general condition for a ________ process.

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What is ΔS° at 298 K for the following reaction? Fe₂O₃(s) + 3CO(g) → 3CO₂(g) + 2Fe(s)

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Predict the sign of ΔS for the reaction O₂(g) → 2O(g).

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