Question 1

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO2(g) → CaCO3(s)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction.

Question 2

Calculate ΔS° for the reaction 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

Accepted Answer

A) −118.2 J/K 
B) −104.8 J/K 
C) 104.8 J/K 
D) 118.2 J/K 
E) 1270.0 J/K 
A) −118.2 J/K 
B) −104.8 J/K 
C) 104.8 J/K 
D) 118.2 J/K 
E) 1270.0 J/K

Question 3

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl2(g) → PbCl2(s)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/T 
E) More information is needed to make a reasonable prediction.

Question 4

A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that ΔG = ΔG°. What conclusion can reasonably be drawn about the reaction at this time?

Accepted Answer

A) K > Q B) K < Q C) K = Q D) K = 1 E) Q = 1 A) K > Q B) K < Q C) K = Q D) K = 1 E) Q = 1

Question 5

The free energy of a perfect crystal at absolute zero, is zero.

Accepted Answer

A) True 
 B)False

Question 6

Which relationship best describes ΔS° for the following reaction? 8H2(g) + S8(s) → 8H2S(g)

Accepted Answer

A) Δ S° = Δ H° 
B) Δ S° = Δ H°/ T 
C) Δ S° ≈ 0 
D) Δ S°  0 
A) Δ S° = Δ H° 
B) Δ S° = Δ H°/ T 
C) Δ S° ≈ 0 
D) Δ S°  0

Question 7

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.2NO(g) + Cl2(g) → 2NOCl(g)   What is the value of ΔG° for this reaction at 550 K?

Accepted Answer

A) -143.76 kJ 
B) -78.78 kJ 
C) -22.24 kJ 
D) -10.56 kJ 
E) 66600 kJ 
A) -143.76 kJ 
B) -78.78 kJ 
C) -22.24 kJ 
D) -10.56 kJ 
E) 66600 kJ

Question 8

For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

Accepted Answer

A) Δ S° > 0, Δ H° > 0 
B) Δ S° > 0, Δ H°  0 
E) All reactions are spontaneous at some temperature. 
A) Δ S° > 0, Δ H° > 0 
B) Δ S° > 0, Δ H°  0 
E) All reactions are spontaneous at some temperature.

Question 9

Consider the reaction CuI(s) ⇄ Cu+(aq) + I−(aq)
If the concentrations of the Cu+ and I− ions in equilibrium at 298 K are both equal to 1.03 × 10−6 M, what is the value of ΔG° for the reaction?

Accepted Answer

A) −68 kJ 
B) 68 kJ 
C) −30 kJ 
D) 30 kJ 
E) 34 kJ 
A) −68 kJ 
B) 68 kJ 
C) −30 kJ 
D) 30 kJ 
E) 34 kJ

Question 10

In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O2(g)
For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Accepted Answer

A) The reaction is only spontaneous at low temperatures. 
B) The reaction is spontaneous at all temperatures. 
C) ΔG° becomes less favorable as the temperature is raised. 
D) The reaction is spontaneous only at high temperatures. 
E) The reaction is spontaneous under standard conditions at 25°C. 
A) The reaction is only spontaneous at low temperatures. 
B) The reaction is spontaneous at all temperatures. 
C) ΔG° becomes less favorable as the temperature is raised. 
D) The reaction is spontaneous only at high temperatures. 
E) The reaction is spontaneous under standard conditions at 25°C.

Question 11

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O2(g) → Hg(l) + SO2(g)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction.

Question 12

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

Accepted Answer

A) Δ S° > 0, Δ H° > 0 
B) Δ S° > 0, Δ H°  0 
E) Δ G° > 0 
A) Δ S° > 0, Δ H° > 0 
B) Δ S° > 0, Δ H°  0 
E) Δ G° > 0

Question 13

Under a given set of conditions, all microstates of a system are equally probable.

Accepted Answer

A) True 
 B)False

Question 14

Which relationship or statement best describes ΔS° for the following reaction? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = H°/ T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = H°/ T 
E) More information is needed to make a reasonable prediction.

Question 15

Which relationship or statement best describes ΔS° for the following reaction? 2H2S(g) + 3O2(g) → 2H2O(g) + 2SO2(g)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = Δ H°/ T 
E) More information is needed to make a reasonable prediction.

Question 16

Which relationship or statement best describes ΔS° for the following reaction? O3(g) + NO(g) → O2(g) + NO2(g)

Accepted Answer

A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = ΔH°/T 
E) More information is needed to make a reasonable prediction. 
A) Δ S° ≈ 0 
B) Δ S°  0 
D) Δ S° = ΔH°/T 
E) More information is needed to make a reasonable prediction.

Question 17

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Accepted Answer

A) 1 mole He( g); 1 mole Kr( g) 
B) 1 mole O 2( g); 2 mole O( g) 
C) 1 mole CH 4( g); 1 mole C 2H 6( g) 
D) 1 mole Xe( g)at 1 atmosphere; 1 mole Xe( g)at 0.5 atmosphere 
E) 20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people 
A) 1 mole He( g); 1 mole Kr( g) 
B) 1 mole O 2( g); 2 mole O( g) 
C) 1 mole CH 4( g); 1 mole C 2H 6( g) 
D) 1 mole Xe( g)at 1 atmosphere; 1 mole Xe( g)at 0.5 atmosphere 
E) 20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people

Question 18

For a reaction at equilibrium, ΔSuniv = 0.

Accepted Answer

A) True 
 B)False

Question 19

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

Accepted Answer

A) True 
 B)False

Question 20

For any reaction, if ΔG° > 0, then K < 1.

Accepted Answer

A) True 
 B)False

Exam 20: Thermodynamics: Entropy, Free Energy, and Reaction Direction

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO2(g) → CaCO3(s)

Calculate ΔS° for the reaction 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl2(g) → PbCl2(s)

A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that ΔG = ΔG°. What conclusion can reasonably be drawn about the reaction at this time?

The free energy of a perfect crystal at absolute zero, is zero.

Which relationship best describes ΔS° for the following reaction? 8H2(g) + S8(s) → 8H2S(g)

Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.2NO(g) + Cl2(g) → 2NOCl(g) What is the value of ΔG° for this reaction at 550 K?

For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

Consider the reaction CuI(s) ⇄ Cu+(aq) + I−(aq) If the concentrations of the Cu+ and I− ions in equilibrium at 298 K are both equal to 1.03 × 10−6 M, what is the value of ΔG° for the reaction?

In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O2(g) For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O2(g) → Hg(l) + SO2(g)

For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

Under a given set of conditions, all microstates of a system are equally probable.

Which relationship or statement best describes ΔS° for the following reaction? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

Which relationship or statement best describes ΔS° for the following reaction? 2H2S(g) + 3O2(g) → 2H2O(g) + 2SO2(g)

Which relationship or statement best describes ΔS° for the following reaction? O3(g) + NO(g) → O2(g) + NO2(g)

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

For a reaction at equilibrium, ΔSuniv = 0.

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

For any reaction, if ΔG° > 0, then K < 1.

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO₂(g) → CaCO₃(s)

Calculate ΔS° for the reaction 2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl₂(g) → PbCl₂(s)

Which relationship best describes ΔS° for the following reaction? 8H₂(g) + S₈(s) → 8H₂S(g)

Consider the reaction CuI(s) ⇄ Cu⁺(aq) + I⁻(aq) If the concentrations of the Cu⁺ and I⁻ ions in equilibrium at 298 K are both equal to 1.03 × 10⁻⁶ M, what is the value of ΔG° for the reaction?

In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O₂(g) For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O₂(g) → Hg(l) + SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

Which relationship or statement best describes ΔS° for the following reaction? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? O₃(g) + NO(g) → O₂(g) + NO₂(g)

For a reaction at equilibrium, ΔS_univ = 0.