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) B) and E)
G) None of the above

Question 2

________ is the pressure required for standard entropy conditions.

Accepted Answer

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

Question 3

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

Question 5

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) A) and B)
F) A) and D)

Question 6

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 B)
G) A) and C)

Question 7

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

Question 8

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 9

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

Question 10

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) D) and E)
G) None of the above

Question 11

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) C) and D)
G) A) and B)

Question 12

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

Question 13

At equilibrium, ΔG° = 0.

Accepted Answer

A) True 
 B)False

Question 14

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) C) and E)
G) A) and D)

Question 15

How does the entropy change when a gas is liquified?

Accepted Answer

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

Question 16

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

Accepted Answer

A) True 
 B)False

Question 17

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

Question 18

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) D) and E)
G) B) and D)

Question 19

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) D) and E)
G) A) and C)

Question 20

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

Exam 18: Entropy, Free Energy, and Equilibrium

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

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

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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 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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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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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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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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At equilibrium, ΔG° = 0.

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

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How does the entropy change when a gas is liquified?

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________ is the pressure required for standard entropy conditions.

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

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

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

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

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

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

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

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

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