Question 1

Which of the following is always true for an exothermic process?

Accepted Answer

A) q sys > 0, Δ S surr sys surr > 0 C) q sys surr sys > 0, Δ S surr > 0 E) w < 0 A) q sys > 0, Δ S surr sys surr > 0 C) q sys surr sys > 0, Δ S surr > 0 E) w < 0

Question 2

For a process with ΔS < 0, which one of the following statements is correct?

Accepted Answer

A) The process will definitely be spontaneous if ΔH surr > 0. 
A) The process will definitely be spontaneous if ΔH surr > 0.

Question 3

Calculate ΔG° for the reaction of ammonia with fluorine. 2NH3(g) + 5F2(g) → N2F4(g) + 6HF(g)

Accepted Answer

A) 179.1 kJ 
B) −179.1 kJ 
C) 1539.7 kJ 
D) −1539.7 kJ 
E) None of these choices are correct. 
A) 179.1 kJ 
B) −179.1 kJ 
C) 1539.7 kJ 
D) −1539.7 kJ 
E) None of these choices are correct.

Question 4

When a sky diver free-falls through the air, the process is

Accepted Answer

A) non-spontaneous because he is accelerating due to the force applied by gravity. 
B) non-spontaneous because he is losing potential energy. 
C) non-spontaneous, if he had planned the jump for two weeks. 
D) spontaneous. 
E) in equilibrium. 
A) non-spontaneous because he is accelerating due to the force applied by gravity. 
B) non-spontaneous because he is losing potential energy. 
C) non-spontaneous, if he had planned the jump for two weeks. 
D) spontaneous. 
E) in equilibrium.

Question 5

Use the given data at 298 K to calculate ΔG° for the reaction 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

Accepted Answer

A) 129.3 kJ 
B) 133.6 kJ 
C) 196.0 kJ 
D) 199.8 kJ 
E) 229.6 kJ 
A) 129.3 kJ 
B) 133.6 kJ 
C) 196.0 kJ 
D) 199.8 kJ 
E) 229.6 kJ

Question 6

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl3(g) + 1.5H2(g) → B(s) + 3HCl(g)
  If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl3(g)?

Accepted Answer

A) −18.2 J/K·mol 
B) 18.2 J/K·mol 
C) 290.1 J/K·mol 
D) 355.4 J/K.mol 
E) 450.6 J/K·mol 
A) −18.2 J/K·mol 
B) 18.2 J/K·mol 
C) 290.1 J/K·mol 
D) 355.4 J/K.mol 
E) 450.6 J/K·mol

Question 7

In a spontaneous process, the entropy of the system always increases.

Accepted Answer

A) True 
 B)False

Question 8

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Accepted Answer

A) CO( g), CO 2( g) 
B) NaCl( s), NaCl( aq) 
C) H 2S( g), H 2S( aq) 
D) Li( s), Pb( s) 
E) H 2( g), H 2O( g) 
A) CO( g), CO 2( g) 
B) NaCl( s), NaCl( aq) 
C) H 2S( g), H 2S( aq) 
D) Li( s), Pb( s) 
E) H 2( g), H 2O( g)

Question 9

Which relationship best describes ΔS° for the following reaction? CO(g) + H2O(g) → CO2(g) + H2(g)

Accepted Answer

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

Question 10

For a given reaction, a change in the pressure may result in a change in the sign of ΔG.

Accepted Answer

A) True 
 B)False

Question 11

Select the correct statement of a law of thermodynamics.

Accepted Answer

A) The enthalpy of the universe is constantly increasing. 
B) The entropy of the universe is constant. 
C) The entropy of an element in its standard state at 25°C is zero. 
D) Every spontaneous process is accompanied by an increase in total entropy. 
E) Every spontaneous process is accompanied by a decrease in the enthalpy of the system. 
A) The enthalpy of the universe is constantly increasing. 
B) The entropy of the universe is constant. 
C) The entropy of an element in its standard state at 25°C is zero. 
D) Every spontaneous process is accompanied by an increase in total entropy. 
E) Every spontaneous process is accompanied by a decrease in the enthalpy of the system.

Question 12

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide. H2O2(l) ⇄ H2O2(g)
Use the following thermodynamic information at 298 K to determine this temperature.

Accepted Answer

A) 120°C 
B) 144°C 
C) 196°C 
D) 418°C 
E) 585°C 
A) 120°C 
B) 144°C 
C) 196°C 
D) 418°C 
E) 585°C

Question 13

The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

Accepted Answer

A) True 
 B)False

Question 14

In order for a process to be spontaneous,

Accepted Answer

A) Δ H must be less than zero. 
B) Δ S must be greater than zero. 
C) Δ G must be greater than zero. 
D) it should be rapid. 
E) Δ S sys + Δ S surr must be greater than zero. 
A) Δ H must be less than zero. 
B) Δ S must be greater than zero. 
C) Δ G must be greater than zero. 
D) it should be rapid. 
E) Δ S sys + Δ S surr must be greater than zero.

Question 15

In order for a process to be spontaneous,

Accepted Answer

A) the entropy of the system must increase. 
B) the entropy of the surroundings must increase. 
C) the entropy of the universe must decrease. 
D) the entropy of the surroundings must decrease. 
E) the entropy change of the surroundings plus the entropy change of the system must be positive. 
A) the entropy of the system must increase. 
B) the entropy of the surroundings must increase. 
C) the entropy of the universe must decrease. 
D) the entropy of the surroundings must decrease. 
E) the entropy change of the surroundings plus the entropy change of the system must be positive.

Question 16

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH4(g) + 2H2O(g) ⇄ CO2(g) + 4H2(g)

Accepted Answer

A) 658 K 
B) 683 K 
C) 955 K 
D) 1047 K 
E) 1229 K 
A) 658 K 
B) 683 K 
C) 955 K 
D) 1047 K 
E) 1229 K

Question 17

A certain process has ΔSuniv > 0 at 25°C. What does one know about the process?

Accepted Answer

A) It is exothermic. 
B) It is endothermic. 
C) It is spontaneous at 25°C. 
D) It will move rapidly toward equilibrium. 
E) None of these choices are correct. 
A) It is exothermic. 
B) It is endothermic. 
C) It is spontaneous at 25°C. 
D) It will move rapidly toward equilibrium. 
E) None of these choices are correct.

Question 18

In some spontaneous processes, the entropy of the surroundings decreases.

Accepted Answer

A) True 
 B)False

Question 19

Use the thermodynamic data at 298 K below to determine the Ksp for barium carbonate, BaCO3 at this temperature.

Accepted Answer

A) 5.86 
B) 6.30 × 10 8 
C) 1.59 × 10 −9 
D) 5.47 × 10 −21 
E) 2.18 × 10 −27 
A) 5.86 
B) 6.30 × 10 8 
C) 1.59 × 10 −9 
D) 5.47 × 10 −21 
E) 2.18 × 10 −27

Question 20

Given: H2O(l) → H2O(g) ΔH° = 40.7 kJ at 373K What is the entropy change in the system (ΔS) when one mole of water vaporizes at 100°C and a pressure of one atmosphere?

Accepted Answer

A) 407 J/K 
B) −407 J/K 
C) 109 J/K 
D) −109 J/K 
E) J/K 
A) 407 J/K 
B) −407 J/K 
C) 109 J/K 
D) −109 J/K 
E) J/K

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

Which of the following is always true for an exothermic process?

For a process with ΔS < 0, which one of the following statements is correct?

Calculate ΔG° for the reaction of ammonia with fluorine. 2NH3(g) + 5F2(g) → N2F4(g) + 6HF(g)

When a sky diver free-falls through the air, the process is

Use the given data at 298 K to calculate ΔG° for the reaction 2Cl2(g) + SO2(g) → SOCl2(g) + Cl2O(g)

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl3(g) + 1.5H2(g) → B(s) + 3HCl(g) If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl3(g)?

In a spontaneous process, the entropy of the system always increases.

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Which relationship best describes ΔS° for the following reaction? CO(g) + H2O(g) → CO2(g) + H2(g)

For a given reaction, a change in the pressure may result in a change in the sign of ΔG.

Select the correct statement of a law of thermodynamics.

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide. H2O2(l) ⇄ H2O2(g) Use the following thermodynamic information at 298 K to determine this temperature.

The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

In order for a process to be spontaneous,

In order for a process to be spontaneous,

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH4(g) + 2H2O(g) ⇄ CO2(g) + 4H2(g)

A certain process has ΔSuniv > 0 at 25°C. What does one know about the process?

In some spontaneous processes, the entropy of the surroundings decreases.

Use the thermodynamic data at 298 K below to determine the Ksp for barium carbonate, BaCO3 at this temperature.

Given: H2O(l) → H2O(g) ΔH° = 40.7 kJ at 373K What is the entropy change in the system (ΔS) when one mole of water vaporizes at 100°C and a pressure of one atmosphere?

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

Calculate ΔG° for the reaction of ammonia with fluorine. 2NH₃(g) + 5F₂(g) → N₂F₄(g) + 6HF(g)

Use the given data at 298 K to calculate ΔG° for the reaction 2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

Elemental boron can be formed by reaction of boron trichloride with hydrogen. BCl₃(g) + 1.5H₂(g) → B(s) + 3HCl(g) If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl₃(g)?

Which relationship best describes ΔS° for the following reaction? CO(g) + H₂O(g) → CO₂(g) + H₂(g)

The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide. H₂O₂(l) ⇄ H₂O₂(g) Use the following thermodynamic information at 298 K to determine this temperature.

The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K. CH₄(g) + 2H₂O(g) ⇄ CO₂(g) + 4H₂(g)

A certain process has ΔS_univ > 0 at 25°C. What does one know about the process?

Use the thermodynamic data at 298 K below to determine the K_sp for barium carbonate, BaCO₃ at this temperature.

Given: H₂O(l) → H₂O(g) ΔH° = 40.7 kJ at 373K What is the entropy change in the system (ΔS) when one mole of water vaporizes at 100°C and a pressure of one atmosphere?