Question 1

What is ΔG°rxn at 298 K for the following reaction? 2Cl2(g)  + SO2(g)  → SOCl2(g)  + Cl2O(g)  rxn at 298 K for the following reaction? 2Cl2(g)  + SO2(g)  → SOCl2(g)  + Cl2O(g)    A)  129.3 kJ/mol B)  133.4 kJ/mol C)  196.0 kJ/mol D)  199.8 kJ/mol E)  229.6 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   129.3 kJ/mol
B)   133.4 kJ/mol
C)   196.0 kJ/mol
D)   199.8 kJ/mol
E)   229.6 kJ/molF) A) and B)
G) A) and C)

Question 2

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) C) and D)
F) A) and D)

Question 3

HI has a normal boiling point of -35.4°C, and its ΔHvap is 21.16 kJ/mol. What is the molar entropy of vaporization (ΔSvap)  of HI?

Accepted Answer

A)   598 J/K • mol
B)   68.6 J/K • mol
C)   75.2 J/K • mol
D)   0.068 J/K • mol
E)   89.0 J/K • molF) C) and E)
G) A) and E)

Question 4

The absolute standard entropy of atom X(g)  is 100 J/K • mol. Which is a reasonable value for the absolute standard entropy of X2(g) ?

Accepted Answer

A)   200 J/K • mol
B)   170 J/K • mol
C)   100 J/K • mol
D)   80 J/K • mol
E)   50 J/K • molF) C) and D)
G) B) and E)

Question 5

The following reaction is spontaneous under standard state conditions at 25°C:
AgCl(s) → Ag+ (aq) + Cl- (aq) (ΔG° = 55 kJ/mol)

Accepted Answer

A) True 
 B)False

Question 6

The entropy change ΔS° at 298 K for the reaction NH4Cl(s) →NH3(g) + HCl(g) is negative.

Accepted Answer

A) True 
 B)False

Question 7

The higher the pressure of a gas sample, the greater is its entropy.

Accepted Answer

A) True 
 B)False

Question 8

At equilibrium, ΔG° = 0.

Accepted Answer

A) True 
 B)False

Question 9

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 B)
G) A) and D)

Question 10

Consider the figure below which shows ΔG° for a chemical process plotted against absolute temperature. Which one of the following is an incorrect conclusion, based on the information in the diagram?  0. B)  ΔS° > 0. C)  The reaction is spontaneous at high temperatures. D)  ΔS° increases with temperature while ΔH° remains constant. E)  There exists a certain temperature at which ΔH° = TΔS°." class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   ΔH° > 0.
B)   ΔS° > 0.
C)   The reaction is spontaneous at high temperatures.
D)   ΔS° increases with temperature while ΔH° remains constant.
E)   There exists a certain temperature at which ΔH° = TΔS°.F) A) and E)
G) C) and E)

Question 11

What is defined as a measure of the randomness or disorder of a system?

Accepted Answer

A)   Gibbs free energy
B)   Entropy
C)   Spontaneous process
D)   Nonspontaneous process
E)   EnthalpyF) D) and E)
G) C) and D)

Question 12

The reaction SiO2(s) + Pb(s) → PbO2(s) + Si(s) is spontaneous:
ΔG°f (PbO2(s)) = -217 kJ/mol
ΔG°f (SiO2(s)) = -856 kJ/mol

Accepted Answer

A) True 
 B)False

Question 13

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) All of the above
G) A) and D)

Question 14

For a chemical reaction to be spontaneous only at high temperatures, which conditions must be met?

Accepted Answer

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

Question 15

________ is the pressure required for standard entropy conditions.

Accepted Answer

The answer of ________ is the pressure required for standard...

Question 16

Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s)  → Na2CO3(s)  + CO2(g)  + H2O(g) 
At 25°C, for this reaction, ΔH°rxn = 128.9 kJ/mol and ΔG°rxn = 33.1 kJ/mol. Above what minimum temperature will the reaction become spontaneous under standard state conditions?

Accepted Answer

A)   0.4 K
B)   3.9 K
C)   321 K
D)   401 K
E)   525 KF) None of the above
G) A) and B)

Question 17

What is ΔG°rxn for the following reaction? 2NO(g)  + Cl2(g)  → 2NOCl(g)  rxn for the following reaction? 2NO(g)  + Cl2(g)  → 2NOCl(g)    A)  -40.40 kJ/mol B)  +40.40 kJ/mol C)  -20.20 kJ/mol D)  +20.20 kJ/mol E)  +152.90 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -40.40 kJ/mol
B)   +40.40 kJ/mol
C)   -20.20 kJ/mol
D)   +20.20 kJ/mol
E)   +152.90 kJ/molF) A) and E)
G) B) and E)

Question 18

How does the entropy change when a gas is liquified?

Accepted Answer

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

Question 19

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

Accepted Answer

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

Question 20

Ozone (O3)  in the atmosphere can react with nitric oxide (NO)  as follows. O3(g)  + NO(g)  → NO2(g)  + O2(g) . ΔH°rxn = -199 kJ/mol, ΔS°rxn = -4.1 J/K • mol
What is ΔG°rxn for this reaction at 25°C?

Accepted Answer

A)   1020 kJ/mol
B)   -1.22 × 103 kJ/mol
C)   2.00 × 103 kJ/mol
D)   -1.42 × 103 kJ/mol
E)   -198 kJ/molF) A) and C)
G) B) and D)

Exam 18: Entropy, Free Energy, and Equilibrium

What is defined as a measure of the randomness or disorder of a system?

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The absolute standard entropy of atom X(g) is 100 J/K • mol. Which is a reasonable value for the absolute standard entropy of X2(g) ?

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

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For a chemical reaction to be spontaneous only at high temperatures, which conditions must be met?

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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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Consider the figure below which shows ΔG° for a chemical process plotted against absolute temperature. Which one of the following is an incorrect conclusion, based on the information in the diagram?

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The reaction SiO2(s) + Pb(s) → PbO2(s) + Si(s) is spontaneous: ΔG°f (PbO2(s)) = -217 kJ/mol ΔG°f (SiO2(s)) = -856 kJ/mol

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Ozone (O3) in the atmosphere can react with nitric oxide (NO) as follows. O3(g) + NO(g) → NO2(g) + O2(g) . ΔH°rxn = -199 kJ/mol, ΔS°rxn = -4.1 J/K • mol What is ΔG°rxn for this reaction at 25°C?

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HI has a normal boiling point of -35.4°C, and its ΔHvap is 21.16 kJ/mol. What is the molar entropy of vaporization (ΔSvap) of HI?

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What is ΔG°rxn for the following reaction? 2NO(g) + Cl2(g) → 2NOCl(g)

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The higher the pressure of a gas sample, the greater is its entropy.

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Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g) At 25°C, for this reaction, ΔH°rxn = 128.9 kJ/mol and ΔG°rxn = 33.1 kJ/mol. Above what minimum temperature will the reaction become spontaneous under standard state conditions?

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The entropy change ΔS° at 298 K for the reaction NH4Cl(s) →NH3(g) + HCl(g) is negative.

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

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How does the entropy change when a gas is liquified?

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What is ΔG°rxn at 298 K for the following reaction? 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

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The following reaction is spontaneous under standard state conditions at 25°C: AgCl(s) → Ag+ (aq) + Cl- (aq) (ΔG° = 55 kJ/mol)

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At equilibrium, ΔG° = 0.

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________ is the pressure required for standard entropy conditions.

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

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The absolute standard entropy of atom X(g) is 100 J/K • mol. Which is a reasonable value for the absolute standard entropy of X₂(g) ?

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The reaction SiO₂(s) + Pb(s) → PbO₂(s) + Si(s) is spontaneous: ΔG°_f (PbO₂(s)) = -217 kJ/mol ΔG°_f (SiO₂(s)) = -856 kJ/mol

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Ozone (O₃) in the atmosphere can react with nitric oxide (NO) as follows. O₃(g) + NO(g) → NO₂(g) + O₂(g) . ΔH°_rxn = -199 kJ/mol, ΔS°_rxn = -4.1 J/K • mol What is ΔG°_rxn for this reaction at 25°C?

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HI has a normal boiling point of -35.4°C, and its ΔH_vap is 21.16 kJ/mol. What is the molar entropy of vaporization (ΔS_vap) of HI?

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What is ΔG°_rxnfor the following reaction? 2NO(g) + Cl₂(g) → 2NOCl(g)

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Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g) At 25°C, for this reaction, ΔH°_rxn = 128.9 kJ/mol and ΔG°_rxn = 33.1 kJ/mol. Above what minimum temperature will the reaction become spontaneous under standard state conditions?

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The entropy change ΔS° at 298 K for the reaction NH₄Cl(s) →NH₃(g) + HCl(g) is negative.

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

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What is ΔG°_rxnat 298 K for the following reaction? 2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

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The following reaction is spontaneous under standard state conditions at 25°C: AgCl(s) → Ag⁺ (aq) + Cl^- (aq) (ΔG° = 55 kJ/mol)

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