Question 1

Why can endothermic reactions be spontaneous?

Accepted Answer

Even though an endothermic process requi

Question 2

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. 
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 3

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

Question 4

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

Question 5

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

Question 7

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. 
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 8

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

Accepted Answer

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

Question 9

Match the following.
-Q < K

Accepted Answer

A) ΔG  0 
D) ΔG  ΔG° 
A) ΔG  0 
D) ΔG  ΔG°

Question 10

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

Question 11

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

Question 12

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

Question 13

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 
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 14

Define the third law of thermodynamics.

Accepted Answer

The entropy of a per

Question 15

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

Question 16

Match the following.
-Q > K

Accepted Answer

A) ΔG  0 
D) ΔG  ΔG° 
A) ΔG  0 
D) ΔG  ΔG°

Question 17

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. 
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 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. 
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

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. 
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 20

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

Why can endothermic reactions be spontaneous?

Which of the following processes has a ΔS > 0?

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

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

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

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

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

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

Match the following. -Q < K

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

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

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

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

Define the third law of thermodynamics.

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

Match the following. -Q > K

Choose the statement below that is true.

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

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

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

Matter, Measurement, and Problem Solving

Atoms and Elements

Molecules, Compounds and Chemical Equations

Chemical Quantities and Aqueous Reactions

Gases

Thermochemistry

The Quantum-Mechanical Model of the Atom

Periodic Properties of the Elements

Chemical Bonding I: Lewis Theory

Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and

Liquids, Solids, and Intermolecular Forces

Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Aqueous Ionic Equilibrium

Electrochemistry

Radioactivity and Nuclear Chemistry

Filters

Exam 17: Free Energy and Thermodynamics

Why can endothermic reactions be spontaneous?

Which of the following processes has a ΔS > 0?

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

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

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

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

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

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

Match the following. -Q < K

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

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

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

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

Define the third law of thermodynamics.

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

Match the following. -Q > K

Choose the statement below that is true.

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

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

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

Matter, Measurement, and Problem Solving

Atoms and Elements

Molecules, Compounds and Chemical Equations

Chemical Quantities and Aqueous Reactions

Gases

Thermochemistry

The Quantum-Mechanical Model of the Atom

Periodic Properties of the Elements

Chemical Bonding I: Lewis Theory

Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and

Liquids, Solids, and Intermolecular Forces

Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Aqueous Ionic Equilibrium

Electrochemistry

Radioactivity and Nuclear Chemistry

Filters

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

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

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

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

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

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

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

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

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

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

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