Question 1

Determine the equilibrium constant for the following reaction at 298 K. Cl(g)+ O3(g)→ ClO(g)+ O2(g)ΔG° = - 34.5 kJ

Accepted Answer

A)  5.66 × 105 
B)  0.986 
C)  8.96 × 10-7 
D)  4.98 × 10-4 
E)  1.12 × 106 
A)  5.66 × 105 
B)  0.986 
C)  8.96 × 10-7 
D)  4.98 × 10-4 
E)  1.12 × 106

Question 2

Which of the following processes have a ΔS > 0?

Accepted Answer

A)  2 NH3(g) + CO2(g) → NH2CONH2(aq) + H2O(l) 
B)  lithium fluoride forms from its elements 
C)  2 HI(g) → H2(g) + I2(l) 
D)  lithium chloride dissolves in pure water 
E)  All of the above processes have a DS > 0. 
A)  2 NH3(g) + CO2(g) → NH2CONH2(aq) + H2O(l) 
B)  lithium fluoride forms from its elements 
C)  2 HI(g) → H2(g) + I2(l) 
D)  lithium chloride dissolves in pure water 
E)  All of the above processes have a DS > 0.

Question 3

What is TRUE if ln K is negative?

Accepted Answer

A)  ΔG°rxn is positive and the reaction is spontaneous in the forward direction. 
B)  ΔG°rxn is negative and the reaction is spontaneous in the forward direction. 
C)  ΔG°rxn is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔG°rxn is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔG°rxn is zero and the reaction is at equilibrium. 
A)  ΔG°rxn is positive and the reaction is spontaneous in the forward direction. 
B)  ΔG°rxn is negative and the reaction is spontaneous in the forward direction. 
C)  ΔG°rxn is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔG°rxn is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔG°rxn is zero and the reaction is at equilibrium.

Question 4

Below what temperature does the following reaction become nonspontaneous?
I2(s)+ Cl2(g)→ 2 ICl(s)ΔH = +36.0 kJ; ΔS = +158.8 J/K

Accepted Answer

A)  128 K 
B)  227 K 
C)  313 K 
D)  This reaction is nonspontaneous at all temperatures. 
E)  This reaction is spontaneous at all temperatures. 
A)  128 K 
B)  227 K 
C)  313 K 
D)  This reaction is nonspontaneous at all temperatures. 
E)  This reaction is spontaneous at all temperatures.

Question 5

What is TRUE if ln K is positive?

Accepted Answer

A)  ΔG°rxn is positive and the reaction is spontaneous in the forward direction. 
B)  ΔG°rxn is negative and the reaction is spontaneous in the forward direction. 
C)  ΔG°rxn is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔG°rxn is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔG°rxn is zero and the reaction is at equilibrium. 
A)  ΔG°rxn is positive and the reaction is spontaneous in the forward direction. 
B)  ΔG°rxn is negative and the reaction is spontaneous in the forward direction. 
C)  ΔG°rxn is negative and the reaction is spontaneous in the reverse direction. 
D)  ΔG°rxn is positive and the reaction is spontaneous in the reverse direction. 
E)  ΔG°rxn is zero and the reaction is at equilibrium.

Question 6

Which of the following statements is TRUE?

Accepted Answer

A)  There is a "heat tax" for every energy transaction. 
B)  A spontaneous reaction is always a fast reaction. 
C)  The entropy of a system always decreases for a spontaneous process. 
D)  Perpetual motion machines are a possibility in the near future. 
E)  None of the above are true. 
A)  There is a "heat tax" for every energy transaction. 
B)  A spontaneous reaction is always a fast reaction. 
C)  The entropy of a system always decreases for a spontaneous process. 
D)  Perpetual motion machines are a possibility in the near future. 
E)  None of the above are true.

Question 7

What can change the direction of a reversible reaction?

Accepted Answer

A)  change in temperature 
B)  change in pressure 
C)  change in volume 
D)  A, B, and C 
E)  none of the above 
A)  change in temperature 
B)  change in pressure 
C)  change in volume 
D)  A, B, and C 
E)  none of the above

Question 8

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH3(g)+ 5 O2(g)→ 4 NO(g)+ 6 H2O(g)
S°(J/mol∙K)192.8 205.2 210.8 188.8

Accepted Answer

A)  +287.4 J/K 
B)  -401.2 J/K 
C)  +160.0 J/K 
D)  -336.6 J/K 
E)  +178.8 J/K 
A)  +287.4 J/K 
B)  -401.2 J/K 
C)  +160.0 J/K 
D)  -336.6 J/K 
E)  +178.8 J/K

Question 9

What is "free" energy?
 Give a fictitious example.

Accepted Answer

Consider a reaction that is exothermic (

Question 10

Which one of the following has the highest standard molar entropy,S°,at 25°C?

Accepted Answer

A)  H2(g) 
B)  F2(g) 
C)  O2(g) 
D)  N2(g) 
E)  Cl2(g) 
A)  H2(g) 
B)  F2(g) 
C)  O2(g) 
D)  N2(g) 
E)  Cl2(g)

Question 11

Consider a reaction that has a positive 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 12

Identify the compound with the standard free energy of formation equal to zero.

Accepted Answer

A)  K Cl(s) 
B)  H2(g) 
C)  NO(g) 
D)  O3(g) 
E)  It is hard to determine. 
A)  K Cl(s) 
B)  H2(g) 
C)  NO(g) 
D)  O3(g) 
E)  It is hard to determine.

Question 13

Place the following in order of decreasing molar entropy at 298 K. H2 Cl2 F2

Accepted Answer

A)  H2 > Cl2 > F2 
B)  Cl2 > H2 > F2 
C)  F2 > Cl2 > H2 
D)  H2 > F2 > Cl2 
E)  Cl2 > F2 > H2 
A)  H2 > Cl2 > F2 
B)  Cl2 > H2 > F2 
C)  F2 > Cl2 > H2 
D)  H2 > F2 > Cl2 
E)  Cl2 > F2 > H2

Question 14

Identify the compound with the highest standard free energy of formation.

Accepted Answer

A)  NaCl(s) 
B)  H2(g) 
C)  NO(g) 
D)  O3(g) 
E)  It is hard to determine. 
A)  NaCl(s) 
B)  H2(g) 
C)  NO(g) 
D)  O3(g) 
E)  It is hard to determine.

Question 15

Which of the following processes shows a decrease in entropy of the system?

Accepted Answer

A)  2 NO(g) + O2(g) → 2 NO2(g) 
B)  COCl2(g) → CO(g) + Cl2(g) 
C)  CH3OH(l) → CO(g) + 2H2(g) 
D)  Na ClO3(s) → Na+(aq) + ClO3-(aq) 
E)  None of the above will show a decrease in entropy. 
A)  2 NO(g) + O2(g) → 2 NO2(g) 
B)  COCl2(g) → CO(g) + Cl2(g) 
C)  CH3OH(l) → CO(g) + 2H2(g) 
D)  Na ClO3(s) → Na+(aq) + ClO3-(aq) 
E)  None of the above will show a decrease in entropy.

Question 16

Calculate the ΔG°rxn using the following information. 2 H2S(g)+ 3 O2(g)→ 2 SO2(g)+ 2 H2O(g)ΔG°rxn = ?
ΔG°f (kJ/mol)-33.4 -300.1 -228.6

Accepted Answer

A)  +990.6 kJ 
B)  +495.3 kJ 
C)  +528.7 kJ 
D)  +66.8 kJ 
E)  -990.6 kJ 
A)  +990.6 kJ 
B)  +495.3 kJ 
C)  +528.7 kJ 
D)  +66.8 kJ 
E)  -990.6 kJ

Question 17

Determine the equilibrium constant for the following reaction at 498 K. 2 Hg(g)+ O2(g)→ 2 HgO(s)ΔH° = -304.2 kJ; ΔS° = -414.2 J/K

Accepted Answer

A)  1.87 × 1010 
B)  8.10 × 1031 
C)  2.31 × 10-22 
D)  5.34 × 10-11 
E)  4.33 × 1021 
A)  1.87 × 1010 
B)  8.10 × 1031 
C)  2.31 × 10-22 
D)  5.34 × 10-11 
E)  4.33 × 1021

Question 18

Determine the equilibrium constant for the following reaction at 655 K. HCN(g)+ 2 H2(g)→ CH3NH2(g)ΔH° = -158 kJ; ΔS°= -219.9 J/K

Accepted Answer

A)  3.99 × 1012 
B)  13.0 
C)  2.51 × 10-13 
D)  3.26 × 10-12 
E)  3.07 × 1011 
A)  3.99 × 1012 
B)  13.0 
C)  2.51 × 10-13 
D)  3.26 × 10-12 
E)  3.07 × 1011

Question 19

For a particular reaction,the value of ∆H is -48.6 kJ/mol and ∆S is -254J/mol K.When is this reaction spontaneous (assuming that ∆H and ∆S do not vary as the temperature changes).

Accepted Answer

A)  At T  191K 
C)  At T < 464K 
D)  This reaction is spontaneous at all temperatures 
E)  This reaction is not spontaneous at all temperatures 
A)  At T  191K 
C)  At T < 464K 
D)  This reaction is spontaneous at all temperatures 
E)  This reaction is not spontaneous at all temperatures

Question 20

For a particular reaction,the value of ∆H is -38.6 kJ/mol and ∆S is +154 J/mol K.When is this reaction spontaneous (assuming that ∆H and ∆S do not vary as the temperature changes).

Accepted Answer

A)  At T  251K 
C)  At T < 524 K 
D)  This reaction is spontaneous at all temperatures 
E)  This reaction is not spontaneous at all temperatures 
A)  At T  251K 
C)  At T < 524 K 
D)  This reaction is spontaneous at all temperatures 
E)  This reaction is not spontaneous at all temperatures

Exam 19: Free Energy and Thermodynamics

Determine the equilibrium constant for the following reaction at 298 K. Cl(g)+ O3(g)→ ClO(g)+ O2(g)ΔG° = - 34.5 kJ

Which of the following processes have a ΔS > 0?

What is TRUE if ln K is negative?

Below what temperature does the following reaction become nonspontaneous? I2(s)+ Cl2(g)→ 2 ICl(s)ΔH = +36.0 kJ; ΔS = +158.8 J/K

What is TRUE if ln K is positive?

Which of the following statements is TRUE?

What can change the direction of a reversible reaction?

Calculate ΔS°rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH3(g)+ 5 O2(g)→ 4 NO(g)+ 6 H2O(g) S°(J/mol∙K)192.8 205.2 210.8 188.8

What is "free" energy? Give a fictitious example.

Which one of the following has the highest standard molar entropy,S°,at 25°C?

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

Identify the compound with the standard free energy of formation equal to zero.

Place the following in order of decreasing molar entropy at 298 K. H2 Cl2 F2

Identify the compound with the highest standard free energy of formation.

Which of the following processes shows a decrease in entropy of the system?

Calculate the ΔG°rxn using the following information. 2 H2S(g)+ 3 O2(g)→ 2 SO2(g)+ 2 H2O(g)ΔG°rxn = ? ΔG°f (kJ/mol)-33.4 -300.1 -228.6

Determine the equilibrium constant for the following reaction at 498 K. 2 Hg(g)+ O2(g)→ 2 HgO(s)ΔH° = -304.2 kJ; ΔS° = -414.2 J/K

Determine the equilibrium constant for the following reaction at 655 K. HCN(g)+ 2 H2(g)→ CH3NH2(g)ΔH° = -158 kJ; ΔS°= -219.9 J/K

For a particular reaction,the value of ∆H is -48.6 kJ/mol and ∆S is -254J/mol K.When is this reaction spontaneous (assuming that ∆H and ∆S do not vary as the temperature changes).

For a particular reaction,the value of ∆H is -38.6 kJ/mol and ∆S is +154 J/mol K.When is this reaction spontaneous (assuming that ∆H and ∆S do not vary as the temperature changes).

Essentials: Units, Measurements, and Problem Solving

Atoms

The Quantum Mechanical Model of the Atom

Periodic Properties of the Elements

Molecules and Compounds

Chemical Bonding I

Chemical Bonding Ii

Chemical Reactions and Chemical Quantities

Introduction to Solutions and Aqueous Reactions

Thermochemistry

Gases

Liquids, Solids, and Intermolecular Forces

Crystalline Solids and Modern Materials

Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Aqueous Ionic Equilibrium

Electrochemistry

Radioactivity and Nuclear Chemistry

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Determine the equilibrium constant for the following reaction at 298 K. Cl(g)+ O₃(g)→ ClO(g)+ O₂(g)ΔG° = - 34.5 kJ

Below what temperature does the following reaction become nonspontaneous? I₂(s)+ Cl₂(g)→ 2 ICl(s)ΔH = +36.0 kJ; ΔS = +158.8 J/K

Calculate ΔS°_rxn for the following reaction.The S° for each species is shown below the reaction. 4 NH₃(g)+ 5 O₂(g)→ 4 NO(g)+ 6 H₂O(g) S°(J/mol^∙K)192.8 205.2 210.8 188.8

Place the following in order of decreasing molar entropy at 298 K. H₂ Cl₂ F₂

Calculate the ΔG°_rxn using the following information. 2 H₂S(g)+ 3 O₂(g)→ 2 SO₂(g)+ 2 H₂O(g)ΔG°_rxn= ? ΔG°_f (kJ/mol)-33.4 -300.1 -228.6

Determine the equilibrium constant for the following reaction at 498 K. 2 Hg(g)+ O₂(g)→ 2 HgO(s)ΔH° = -304.2 kJ; ΔS° = -414.2 J/K

Determine the equilibrium constant for the following reaction at 655 K. HCN(g)+ 2 H₂(g)→ CH₃NH₂(g)ΔH° = -158 kJ; ΔS°= -219.9 J/K