Question 1

What is the ΔG for the forward reaction at 100°C?
C2H4(g) + H2(g) ⇌ C2H6(g) ;ΔH= -137.5 kJ;ΔS = -120.5 J/K

Accepted Answer

A)  182.4 kJ
B)  -92.55 kJ
C)  44.81 kJ
D)  -115.4 kJ

Question 2

Determine ΔG°rxn using the following information.
H2(g) + CO(g) → CH2O(g) ΔH° = +1.9 kJ;ΔS° = -109.6 J/K

Accepted Answer

A)  +57.7 kJ
B)  -30.8 kJ
C)  +34.6 kJ
D)  -41.5 kJ
E)  +17.3 kJ

Question 3

Match the following.
-Q > K

Accepted Answer

A)  ΔG 
B)  standard state
C)  ΔG > 0
D)  ΔG 
E)  equilibriumF) K = 0G) ΔG > ΔG°

Question 4

Which process results in the decrease of entropy of the universe?

Accepted Answer

A)  the cooling of a hot cup of coffee in room temperature air
B)  the condensation of water vapor on windows
C)  the melting of snow above 0°C
D)  all of the above

Question 5

When solid NH4NO3 dissolves spontaneously in water,the resulting solution becomes cool.Which answer is consistent with this observation?
4NO3 dissolves spontaneously in water,the resulting solution becomes cool.Which answer is consistent with this observation?   A) I B) II C) III D) IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IV

Question 6

Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction.
SO3(g) + H2O(g) → H2SO4(l) ΔG°= -90.5 kJ
P(SO3) = 0.20 atm,P(H2O) = 0.88 atm

Accepted Answer

A)  +15.9 kJ
B)  -90.5 kJ
C)  +51.4 kJ
D)  -86.2 kJ
E)  -30.4 kJ

Question 7

Estimate ΔG°rxn for the following reaction at 387 K.
HCN(g) + 2 H2(g) → CH3NH2(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

Accepted Answer

A)  +243 kJ
B)  -72.9 kJ
C)  +84.9 kJ
D)  -92.5 kJ
E)  -188 kJ

Question 8

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction.
C2H2(g) + 2 H2(g) → C2H6(g) 
S°(J/mol∙K) 200.9 130.7 229.2

Accepted Answer

A)  +303.3 J/K
B)  +560.8 J/K
C)  -102.4 J/K
D)  -233.1 J/K
E)  229.2 J/K

Question 9

Choose the statement below that is true.

Accepted Answer

A)  K > 1,ΔG°rxn is positive
B)  K rxn is negative
C)  ΔG°rxn = 0 at equilibrium
D)  ΔGrxn = 0 at equilibrium
E)  None of the above statements are true.

Question 10

Which of the following processes has a ΔS > 0?

Accepted Answer

A)  CH3OH(l) → CH3OH(s) 
B)  N2(g) + 3 H2(g) → 2 NH3(g) 
C)  CH4(g) + H2O(g) → CO(g) + 3 H2(g) 
D)  Na2CO3(s) + H2O(g) + CO2(g) → 2 NaHCO3(s) 
E)  All of the above processes have a ΔS > 0.

Question 11

Calculate the ΔG°rxn using the following information.
2 H2S(g) + 3 O2(g) → 2 SO2(g) + 2 H2O(g) ΔG°rxn = ?
ΔH°f (kJ/mol) -20.6 296.8 -241.8
S°(J/mol∙K) 205.8 205.248.2 188.8

Accepted Answer

A)  +196.8 kJ
B)  +108.2 kJ
C)  -466.1 kJ
D)  +676.2 kJ
E)  -147.1 kJ

Question 12

Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction.
CaCO3(s) → CaO(s) + CO2(g) ΔG° = +131.1 kJ
P(CO2) = 0.033 atm

Accepted Answer

A)  -49.3 kJ
B)  -8.32 kJ
C)  +122.6 kJ
D)  +39.7 kJ
E)  +43.3 kJ

Question 13

Below what temperature does the following reaction become nonspontaneous?
2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) 
ΔH = +136.5 kJ;ΔS = +287.5 J/K

Accepted Answer

A)  39.2 K
B)  151 K
C)  475 K
D)  This reaction is nonspontaneous at all temperatures.
E)  This reaction is spontaneous at all temperatures.

Question 14

What is the ΔSuniv for the following reaction at 25°C?
N2(g) + 3H2(g) ⇌ 2NH3(g) ΔSsys = -197 J/K;ΔHsys = -91.8 kJ

Accepted Answer

A)  +111 J/K
B)  -111 J/K
C)  -505 J/K
D)  +505 J/K

Question 15

Use the free energies of formation given below to calculate the equilibrium constant (K) for the following reaction at 298 K.
2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) K = ?
ΔG°f (kJ/mol) -110.9 87.6 51.3 -237.1

Accepted Answer

A)  8.71 × 108
B)  0.980
C)  1.15 × 10-9
D)  1.02
E)  5.11 × 10-4

Question 16

Consider a reaction that has a negative ΔH and a positive ΔS.Which of the following statements is true?

Accepted Answer

A)  This reaction will be spontaneous only at high temperatures.
B)  This reaction will be spontaneous at all temperatures.
C)  This reaction will be nonspontaneous at all temperatures.
D)  This reaction will be nonspontaneous only at high temperatures.
E)  It is not possible to determine without more information.

Question 17

Why can endothermic reactions be spontaneous?

Accepted Answer

Even though an endothermic process requi...

Question 18

Consider a reaction that has a negative ΔH and a negative ΔS.Which of the following statements is true?

Accepted Answer

A)  This reaction will be spontaneous only at high temperatures.
B)  This reaction will be spontaneous at all temperatures.
C)  This reaction will be nonspontaneous at all temperatures.
D)  This reaction will be nonspontaneous only at high temperatures.
E)  It is not possible to determine without more information.

Question 19

Define the third law of thermodynamics.

Accepted Answer

The entropy of a per...

Question 20

Match the following.
-Q < K

Accepted Answer

A)  ΔG 
B)  standard state
C)  ΔG > 0
D)  ΔG 
E)  equilibriumF) K = 0G) ΔG > ΔG°

Exam 17: Free Energy and Thermodynamics

Define the third law of thermodynamics.

Correct AnswerverifiedThe entropy of a per...View AnswerShow Answer

Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction. SO3(g) + H2O(g) → H2SO4(l) ΔG°= -90.5 kJ P(SO3) = 0.20 atm,P(H2O) = 0.88 atm

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Use the free energies of formation given below to calculate the equilibrium constant (K) for the following reaction at 298 K. 2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) K = ? ΔG°f (kJ/mol) -110.9 87.6 51.3 -237.1

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When solid NH4NO3 dissolves spontaneously in water,the resulting solution becomes cool.Which answer is consistent with this observation?

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Determine ΔG°rxn using the following information. H2(g) + CO(g) → CH2O(g) ΔH° = +1.9 kJ;ΔS° = -109.6 J/K

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Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. C2H2(g) + 2 H2(g) → C2H6(g) S°(J/mol∙K) 200.9 130.7 229.2

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Choose the statement below that is true.

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Which of the following processes has a ΔS > 0?

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What is the ΔSuniv for the following reaction at 25°C? N2(g) + 3H2(g) ⇌ 2NH3(g) ΔSsys = -197 J/K;ΔHsys = -91.8 kJ

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Why can endothermic reactions be spontaneous?

Correct AnswerverifiedEven though an endothermic process requi...View AnswerShow Answer

Match the following. -Q < K

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Match the following. -Q > K

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Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction. CaCO3(s) → CaO(s) + CO2(g) ΔG° = +131.1 kJ P(CO2) = 0.033 atm

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Estimate ΔG°rxn for the following reaction at 387 K. HCN(g) + 2 H2(g) → CH3NH2(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

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Consider a reaction that has a negative ΔH and a negative ΔS.Which of the following statements is true?

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Consider a reaction that has a negative ΔH and a positive ΔS.Which of the following statements is true?

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Below what temperature does the following reaction become nonspontaneous? 2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) ΔH = +136.5 kJ;ΔS = +287.5 J/K

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Calculate the ΔG°rxn using the following information. 2 H2S(g) + 3 O2(g) → 2 SO2(g) + 2 H2O(g) ΔG°rxn = ? ΔH°f (kJ/mol) -20.6 296.8 -241.8 S°(J/mol∙K) 205.8 205.248.2 188.8

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Which process results in the decrease of entropy of the universe?

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What is the ΔG for the forward reaction at 100°C? C2H4(g) + H2(g) ⇌ C2H6(g) ;ΔH= -137.5 kJ;ΔS = -120.5 J/K

Correct AnswerverifiedShow Answer

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The entropy of a per...
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Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. SO₃(g) + H₂O(g) → H₂SO₄(l) ΔG°= -90.5 kJ P(SO₃) = 0.20 atm,P(H₂O) = 0.88 atm

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Use the free energies of formation given below to calculate the equilibrium constant (K) for the following reaction at 298 K. 2 HNO₃(aq) + NO(g) → 3 NO₂(g) + H₂O(l) K= ? ΔG°_f (kJ/mol) -110.9 87.6 51.3 -237.1

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When solid NH₄NO₃ dissolves spontaneously in water,the resulting solution becomes cool.Which answer is consistent with this observation?

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Determine ΔG°_rxn using the following information. H₂(g) + CO(g) → CH₂O(g) ΔH° = +1.9 kJ;ΔS° = -109.6 J/K

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Calculate ΔS°_rxn for the following reaction.The S°for each species is shown below the reaction. C₂H₂(g) + 2 H₂(g) → C₂H₆(g) S°(J/mol^∙K) 200.9 130.7 229.2

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What is the ΔS_univ for the following reaction at 25°C? N₂(g) + 3H₂(g) ⇌ 2NH₃(g) ΔS_sys = -197 J/K;ΔH_sys = -91.8 kJ

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Even though an endothermic process requi...
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Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction. CaCO₃(s) → CaO(s) + CO₂(g) ΔG° = +131.1 kJ P(CO₂) = 0.033 atm

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Estimate ΔG°_rxn for the following reaction at 387 K. HCN(g) + 2 H₂(g) → CH₃NH₂(g) ΔH° = -158.0 kJ;ΔS° = -219.9 J/K

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Below what temperature does the following reaction become nonspontaneous? 2 HNO₃(aq) + NO(g) → 3 NO₂(g) + H₂O(l) ΔH = +136.5 kJ;ΔS = +287.5 J/K

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Calculate the ΔG°_rxn using the following information. 2 H₂S(g) + 3 O₂(g) → 2 SO₂(g) + 2 H₂O(g) ΔG°_rxn= ? ΔH°_f (kJ/mol) -20.6 296.8 -241.8 S°(J/mol^∙K) 205.8 205.248.2 188.8

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What is the ΔG for the forward reaction at 100°C? C₂H₄(g) + H₂(g) ⇌ C₂H₆(g) ;ΔH= -137.5 kJ;ΔS = -120.5 J/K

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