Question 1

Which of the following has ΔG°f = 0 at 25°C?

Accepted Answer

A)  H2O(l) 
B)  H2O(g) 
C)  Na(s) 
D)  O3(g) 
E)  O(g) F) A) and B)
G) A) and C)

Question 2

What term is given to the fact that the entropy of a perfect crystalline solid is zero at absolute zero?

Accepted Answer

A)  1st law of thermodynamics
B)  2nd law of thermodynamics
C)  3rd law of thermodynamics
D)  crystalline lattice theory
E)  absolute crystallinityF) A) and B)
G) C) and E)

Question 3

The heat of vaporization of 1-pentanol is 55.5 kJ/mol,and its entropy of vaporization is 148 J/K•mol.What is the approximate boiling point of 1-pentanol?

Accepted Answer

A)  100oC
B)  375 oC
C)  0 oC
D)  25 oCE) B) and C)
F) B) and D)

Question 4

Which of the following substances has the greatest entropy per mole?

Accepted Answer

A)  O2(g) 
B)  N2(g) 
C)  CO(g) 
D)  CO2(g) 
E)  C4H10(g) F) B) and D)
G) A) and B)

Question 5

At constant temperature and pressure,which is the correct relationship between ΔG and other thermodynamic quantities?

Accepted Answer

A)  ΔG = ΔH - TΔS
B)  ΔG = ΔH + TΔS
C)  ΔG = ΔU - TΔS
D)  ΔG = -TΔS
E)  ΔG = q/TF) B) and E)
G) A) and B)

Question 6

Which is true for a system at equilibrium?

Accepted Answer

A)  ΔS°sys = ΔS°surr
B)  ΔS°sys = -ΔS°surr
C)  ΔS°sys = ΔS°surr = 0
D)  ΔS°univ > 0
E)  ΔS°univ < 0F) C) and E)
G) A) and D)

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) C) and E)
G) All of the above

Question 8

Which of the following is an example of a nonspontaneous process?

Accepted Answer

A)  Ice melting at room temperature
B)  Sodium metal reacting violently with water
C)  Rusting of iron at room temperature
D)  A ball rolling downhill
E)  Water freezing at room temperatureF) None of the above
G) All of the above

Question 9

Which statement is correct?

Accepted Answer

A)  Heating always decreases the entropy of a system.
B)  The reaction that results in an increase in the number of moles of gas always decreases the entropy of a system.
C)  The greater number of particles leads to a smaller number of microstates.
D)  An increase in the temperature decreases all types of molecular motions.
E)  The solvation process usually leads to an increase in entropy.F) A) and D)
G) A) and C)

Question 10

State the second and third laws of thermodynamics.

Accepted Answer

All spontaneous processes are ...

Question 11

What is defined as a process that may occur under a specific set of conditions?

Accepted Answer

A)  Conditional process
B)  Nonspontaneous process
C)  Specified process
D)  Spontaneous process
E)  Conditionality lawF) C) and D)
G) All of the above

Question 12

The complete combustion of liquid benzene is represented by the equation:
C6H6(l)+ 7  O2(g)→ 6CO2(g)+ 3H2O(l)
Using the data below,calculate,for this reaction
a.ΔH°
b.ΔG° at 25°C.

Accepted Answer

Substance: C₆H₆(l)O₂(g)...

Question 13

How does the entropy change when a solid is melted?

Accepted Answer

The answer of How does the entropy change when a...

Question 14

How does the entropy change when a gas is liquified?

Accepted Answer

The answer of How does the entropy change when a...

Question 15

What is the third law of thermodynamics?

Accepted Answer

At 0 K all perfectly...

Question 16

Which species will have the lowest absolute entropy at 25°C?

Accepted Answer

A)  C2H5OH(l) 
B)  C2H2(g) 
C)  C3H8(g) 
D)  C3H7OH(l) 
E)  C2H6(g) F) A) and E)
G) A) and D)

Question 17

Which response includes all of the following processes that are accompanied by an increase in entropy? 1.I2(s) → I2(g) 
2) 2I(g) → I2(g) 
3) 2NH3(g) → N2(g) + 3H2(g) 
4) Mg2+(aq) + 2OH-(aq) → Mg(OH) 2(s)

Accepted Answer

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

Question 18

Hydrogen sulfide decomposes according to the following reaction: 2 H2S(g) → 2H2 (g) + S2(g) 
For this reaction at 298 K,ΔS°rxn = 78.1 J/K • mol,ΔH°rxn = 169.4 kJ/mol,and ΔG°rxn = 146.1 kJ/mol.What is ΔG°rxn at 900.K?

Accepted Answer

A)  -69881 kJ/mol
B)  48.4 kJ/mol
C)  99.1 kJ/mol
D)  240 kJ/mol
E)  441 kJ/molF) A) and E)
G) A) and D)

Question 19

Which reaction has the largest ΔS°?

Accepted Answer

A)  2N2H4(g) → 2NH3(g) + H2(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 D)
G) A) and B)

Question 20

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

Exam 18: Entropy Free Energy and Equilibrium

How does the entropy change when a gas is liquified?

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Which of the following substances has the greatest entropy per mole?

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Which of the following is an example of a nonspontaneous process?

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Which statement is correct?

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Which of the following has ΔG°f = 0 at 25°C?

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Which reaction has the largest ΔS°?

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Hydrogen sulfide decomposes according to the following reaction: 2 H2S(g) → 2H2 (g) + S2(g) For this reaction at 298 K,ΔS°rxn = 78.1 J/K • mol,ΔH°rxn = 169.4 kJ/mol,and ΔG°rxn = 146.1 kJ/mol.What is ΔG°rxn at 900.K?

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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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The heat of vaporization of 1-pentanol is 55.5 kJ/mol,and its entropy of vaporization is 148 J/K•mol.What is the approximate boiling point of 1-pentanol?

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The complete combustion of liquid benzene is represented by the equation: C6H6(l)+ 7 O2(g)→ 6CO2(g)+ 3H2O(l) Using the data below,calculate,for this reaction a.ΔH° b.ΔG° at 25°C.

Correct AnswerverifiedSubstance: C6H6(l)O2(g)...View AnswerShow Answer

What is the third law of thermodynamics?

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Which statement is correct?

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Which is true for a system at equilibrium?

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What term is given to the fact that the entropy of a perfect crystalline solid is zero at absolute zero?

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What is defined as a process that may occur under a specific set of conditions?

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State the second and third laws of thermodynamics.

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Which species will have the lowest absolute entropy at 25°C?

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How does the entropy change when a solid is melted?

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At constant temperature and pressure,which is the correct relationship between ΔG and other thermodynamic quantities?

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Which response includes all of the following processes that are accompanied by an increase in entropy? 1.I2(s) → I2(g) 2) 2I(g) → I2(g) 3) 2NH3(g) → N2(g) + 3H2(g) 4) Mg2+(aq) + 2OH-(aq) → Mg(OH) 2(s)

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Which of the following has ΔG°_f = 0 at 25°C?

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Hydrogen sulfide decomposes according to the following reaction: 2 H₂S(g) → 2H₂ (g) + S₂(g) For this reaction at 298 K,ΔS°_rxn = 78.1 J/K • mol,ΔH°_rxn = 169.4 kJ/mol,and ΔG°_rxn = 146.1 kJ/mol.What is ΔG°_rxn at 900.K?

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The complete combustion of liquid benzene is represented by the equation: C₆H₆(l)+ 7 O₂(g)→ 6CO₂(g)+ 3H₂O(l) Using the data below,calculate,for this reaction a.ΔH° b.ΔG° at 25°C.

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Substance: C₆H₆(l)O₂(g)...
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At 0 K all perfectly...
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All spontaneous processes are ...
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Which response includes all of the following processes that are accompanied by an increase in entropy? 1.I₂(s) → I₂(g) 2) 2I(g) → I₂(g) 3) 2NH₃(g) → N₂(g) + 3H₂(g) 4) Mg²⁺(aq) + 2OH^-(aq) → Mg(OH) ₂(s)

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