Question 1

Which one of the following processes produces a decrease of the entropy of the system?

Accepted Answer

A) dissolving sodium chloride in water 
B) sublimation of naphthalene 
C) dissolving oxygen in water 
D) boiling of alcohol 
E) explosion of nitroglycerine 
A) dissolving sodium chloride in water 
B) sublimation of naphthalene 
C) dissolving oxygen in water 
D) boiling of alcohol 
E) explosion of nitroglycerine

Question 2

Consider the reaction: Ag+ (aq) + Cl- (aq) → AgCl (s)
Given the following table of thermodynamic data at 298 K:   The value of K for the reaction at 25 °C is ________.

Accepted Answer

A) 810 
B) 5.3 × 109 
C) 1.8 × 104 
D) 3.7 × 1010 
E) 1.9 × 10-10 
A) 810 
B) 5.3 × 109 
C) 1.8 × 104 
D) 3.7 × 1010 
E) 1.9 × 10-10

Question 3

The value of ΔS° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO2 (g) → S (s, rhombic) + O2 (g)
Is ________ J/K ∙ mol.

Accepted Answer

A) +485.4 
B) +248.5 
C) -11.6 
D) -248.5 
E) +11.6 
A) +485.4 
B) +248.5 
C) -11.6 
D) -248.5 
E) +11.6

Question 4

Which of the following statements is true?

Accepted Answer

A) Processes that are spontaneous in one direction are spontaneous in the opposite direction. 
B) Processes are spontaneous because they occur at an observable rate. 
C) Spontaneity can depend on the temperature. 
D) All of the statements are true. 
A) Processes that are spontaneous in one direction are spontaneous in the opposite direction. 
B) Processes are spontaneous because they occur at an observable rate. 
C) Spontaneity can depend on the temperature. 
D) All of the statements are true.

Question 5

A reversible process is one that ________.

Accepted Answer

A) can be reversed with no net change in either system or surroundings 
B) happens spontaneously 
C) is spontaneous in both directions 
D) must be carried out at low temperature 
E) must be carried out at high temperature 
A) can be reversed with no net change in either system or surroundings 
B) happens spontaneously 
C) is spontaneous in both directions 
D) must be carried out at low temperature 
E) must be carried out at high temperature

Question 6

The value of ΔG° at 181.0 °C for the formation of calcium chloride from its constituent elements: Ca (s)+ Cl2 (g) → CaCl2 (s)
Is ________ kJ/mol. At 25.0 °C for this reaction, ΔH° is -795.8 kJ/mol, ΔG° is -748.1 kJ/mol, and ΔS° is -159.8 J/K.

Accepted Answer

A) -868.4 
B) -723.2 
C) 7.18 × 104 
D) -766.9 
E) 2.81 × 104 
A) -868.4 
B) -723.2 
C) 7.18 × 104 
D) -766.9 
E) 2.81 × 104

Question 7

For the reaction C(s) + H2O(g) → CO(g) + H2(g)
ΔH° = 133.3 kJ/mol and ΔS° = 121.6 J/K ∙ mol at 298 K. At temperatures greater than ________ °C this reaction is spontaneous under standard conditions.

Accepted Answer

A) 273 
B) 325 
C) 552 
D) 823 
E) 1096 
A) 273 
B) 325 
C) 552 
D) 823 
E) 1096

Question 8

For a given reaction with ΔH = -28.1 kJ/mol, the ΔG = 0 at 372 K. The value of ΔS must be ________ J/K-mol, assuming that ΔH and ΔS do not vary with temperature.

Accepted Answer

A) -75.5 
B) 75.5 
C) -7.55 × 10-5 
D) 7.55 × 10-5 
E) -1.32 × 10-2 
A) -75.5 
B) 75.5 
C) -7.55 × 10-5 
D) 7.55 × 10-5 
E) -1.32 × 10-2

Question 9

Find the temperature (in K)above which a reaction with a ΔH of 53.00 kJ/mol and a ΔS of 100.0 J/K ∙ mol becomes spontaneous.

Accepted Answer

The answer of Find the temperature (in K)above which a...

Question 10

The combustion of ethene in the presence of excess oxygen yields carbon dioxide and water: C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (l)
The value of ΔS° for this reaction is ________ J/K ∙ mol.

Accepted Answer

A) -267.4 
B) -140.9 
C) -347.6 
D) +347.6 
E) +140.9 
A) -267.4 
B) -140.9 
C) -347.6 
D) +347.6 
E) +140.9

Question 11

ΔS is positive for the reaction ________.

Accepted Answer

A) CaO (s) + CO2 (g) → CaCO3 (s) 
B) N2 (g) + 3H2 (g) → 2NH3 (g) 
C) 2SO3 (g) → 2SO2 (g) + O2 (g) 
D) Ag+ (aq) + Cl- (aq) → AgCl (s) 
E) H2O (l) → H2O (s) 
A) CaO (s) + CO2 (g) → CaCO3 (s) 
B) N2 (g) + 3H2 (g) → 2NH3 (g) 
C) 2SO3 (g) → 2SO2 (g) + O2 (g) 
D) Ag+ (aq) + Cl- (aq) → AgCl (s) 
E) H2O (l) → H2O (s)

Question 12

The more negative ΔG° is for a given reaction, the larger the value of the corresponding equilibrium constant, K.

Accepted Answer

A) True 
 B)False

Question 13

Calculate ΔG∘ (in kJ/mol)for the following reaction at 1 atm and 25 °C:
C2H6 (g)+ O2 (g)→ CO2 (g)+ H2O (l) (unbalanced)
ΔHf∘ C2H6 (g)= -84.7 kJ/mol; S∘ C2H6 (g)= 229.5 J/K ∙ mol;
ΔHf∘ CO2 (g)= -393.5 kJ/mol; S∘ CO2 (g)= 213.6 J/K ∙ mol;
ΔHf∘ H2O (l)= -285.8 kJ/mol; S∘ H2O (l)= 69.9 J/K ∙ mol;
S∘ O2 (g)= 205.0 J/K ∙ mol

Accepted Answer

Question 14

The value of ΔH° for the decomposition of POCl3 into its constituent elements, 2POCl3 (g) → P2 (g) + O2 (g) + 3Cl2 (g)
Is ________ kJ/mol.

Accepted Answer

A) -1228.7 
B) +1228.7 
C) -940.1 
D) +940.1 
E) 0.00 
A) -1228.7 
B) +1228.7 
C) -940.1 
D) +940.1 
E) 0.00

Question 15

Given the following table of thermodynamic data,     complete the following sentence. The vaporization of PCl3 (l)is ________.

Accepted Answer

A) nonspontaneous at low temperature and spontaneous at high temperature 
B) spontaneous at low temperature and nonspontaneous at high temperature 
C) spontaneous at all temperatures 
D) nonspontaneous at all temperatures 
E) not enough information given to draw a conclusion 
A) nonspontaneous at low temperature and spontaneous at high temperature 
B) spontaneous at low temperature and nonspontaneous at high temperature 
C) spontaneous at all temperatures 
D) nonspontaneous at all temperatures 
E) not enough information given to draw a conclusion

Question 16

The value of ΔG° at 25 °C for the decomposition of calcium chloride into its constituent elements, CaCl2 (s) → Ca (s) + Cl2 (g)
Is ________ kJ/mol.

Accepted Answer

A) -795.8 
B) +795.8 
C) +763.7 
D) +748.1 
E) -748.1 
A) -795.8 
B) +795.8 
C) +763.7 
D) +748.1 
E) -748.1

Question 17

For a given reaction, ΔH = +74.6 kJ/mol, and the reaction is spontaneous at temperatures above the crossover temperature, 449 K. The value of ΔS = ________ J/mol · K, assuming that ΔH and ΔS do not vary with temperature.

Accepted Answer

A) 166 
B) 6020 
C) -166 
D) -6020 
E) 3.35 × 104 
A) 166 
B) 6020 
C) -166 
D) -6020 
E) 3.35 × 104

Question 18

Which one of the following processes produces a decrease in the entropy of the system?

Accepted Answer

A) freezing of Fe(l)into Fe(s) 
B) evaporation of liquid ethanol into gaseous ethanol 
C) dissolution of LiOH(s)in water 
D) melting ice to form water 
E) mixing of two gases into one container 
A) freezing of Fe(l)into Fe(s) 
B) evaporation of liquid ethanol into gaseous ethanol 
C) dissolution of LiOH(s)in water 
D) melting ice to form water 
E) mixing of two gases into one container

Question 19

Use the table below to answer the questions that follow.
Thermodynamic Quantities for Selected Substances at 298.15 K (25 °C)
Substance ΔH°f (kJ/mol)ΔG°f (kJ/mol)S (J/K-mol)
Carbon
C (s, diamond)1.88 2.84 2.43
C (s, graphite)0 0 5.69
CS1U1B12S1U1B0HS1U1B12S1U1B0 (g)226.7 209.2 200.8
CS1U1B12S1U1B0HS1U1B14S1U1B0 (g)52.30 68.11 219.4
CS1U1B12S1U1B0HS1U1B16S1U1B0 (g)-84.68 -32.89 229.5
CO (g)-110.5 -137.2 197.9
COS1U1B12S1U1B0 (g)-393.5 -394.4 213.6
Hydrogen
HS1U1B12S1U1B0( g)0 0 130.58
Oxygen
OS1U1B12S1U1B0 (g)0 0 205.0
HS1U1B12S1U1B0O (l)-285.83 -237.13 69.91
-The value of ΔS° for the oxidation of carbon to carbon dioxide, C (s, graphite) + O2 (g) → CO2(g)
Is ________ J/K ∙ mol. The combustion of carbon, as in charcoal briquettes, in the presence of abundant oxygen produces carbon dioxide.

Accepted Answer

A) +424.3 
B) +205.0 
C) -205.0 
D) -2.9 
E) +2.9 
A) +424.3 
B) +205.0 
C) -205.0 
D) -2.9 
E) +2.9

Question 20

For the reaction 2 C4H10 (g) + 13 O2 (g)→ 8 CO2 (g) + 10 H2O (g)
ΔH° is -125 kJ/mol and ΔS° is +253 J/K ∙ mol. This reaction is ________.

Accepted Answer

A) spontaneous at all temperatures 
B) spontaneous only at high temperature 
C) spontaneous only at low temperature 
D) nonspontaneous at all temperatures 
E) unable to determine without more information 
A) spontaneous at all temperatures 
B) spontaneous only at high temperature 
C) spontaneous only at low temperature 
D) nonspontaneous at all temperatures 
E) unable to determine without more information

Exam 19: Chemical Thermodynamics

Which one of the following processes produces a decrease of the entropy of the system?

Consider the reaction: Ag+ (aq) + Cl- (aq) → AgCl (s) Given the following table of thermodynamic data at 298 K: The value of K for the reaction at 25 °C is ________.

The value of ΔS° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO2 (g) → S (s, rhombic) + O2 (g) Is ________ J/K ∙ mol.

Which of the following statements is true?

A reversible process is one that ________.

The value of ΔG° at 181.0 °C for the formation of calcium chloride from its constituent elements: Ca (s)+ Cl2 (g) → CaCl2 (s) Is ________ kJ/mol. At 25.0 °C for this reaction, ΔH° is -795.8 kJ/mol, ΔG° is -748.1 kJ/mol, and ΔS° is -159.8 J/K.

For the reaction C(s) + H2O(g) → CO(g) + H2(g) ΔH° = 133.3 kJ/mol and ΔS° = 121.6 J/K ∙ mol at 298 K. At temperatures greater than ________ °C this reaction is spontaneous under standard conditions.

For a given reaction with ΔH = -28.1 kJ/mol, the ΔG = 0 at 372 K. The value of ΔS must be ________ J/K-mol, assuming that ΔH and ΔS do not vary with temperature.

Find the temperature (in K)above which a reaction with a ΔH of 53.00 kJ/mol and a ΔS of 100.0 J/K ∙ mol becomes spontaneous.

The combustion of ethene in the presence of excess oxygen yields carbon dioxide and water: C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (l) The value of ΔS° for this reaction is ________ J/K ∙ mol.

ΔS is positive for the reaction ________.

The more negative ΔG° is for a given reaction, the larger the value of the corresponding equilibrium constant, K.

The value of ΔH° for the decomposition of POCl3 into its constituent elements, 2POCl3 (g) → P2 (g) + O2 (g) + 3Cl2 (g) Is ________ kJ/mol.

Given the following table of thermodynamic data, complete the following sentence. The vaporization of PCl3 (l)is ________.

The value of ΔG° at 25 °C for the decomposition of calcium chloride into its constituent elements, CaCl2 (s) → Ca (s) + Cl2 (g) Is ________ kJ/mol.

For a given reaction, ΔH = +74.6 kJ/mol, and the reaction is spontaneous at temperatures above the crossover temperature, 449 K. The value of ΔS = ________ J/mol · K, assuming that ΔH and ΔS do not vary with temperature.

Which one of the following processes produces a decrease in the entropy of the system?

For the reaction 2 C4H10 (g) + 13 O2 (g)→ 8 CO2 (g) + 10 H2O (g) ΔH° is -125 kJ/mol and ΔS° is +253 J/K ∙ mol. This reaction is ________.

Introduction: Matter and Measurement

Atoms, Molecules, and Ions

Stoichiometry: Calculations With Chemical Formulas and Equations

Aqueous Reactions and Solution Stoichiometry

Thermochemistry

Electronic Structure of Atoms

Periodic Properties of the Elements

Basic Concepts of Chemical Bonding

Molecular Geometry and Bonding Theories

Gases

Liquids and Intermolecular Forces

Solids and Modern Materials

Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acid-Base Equilibria

Additional Aspects of Aqueous Equilibria

Chemistry of the Environment

Electrochemistry

Nuclear Chemistry

Chemistry of the Nonmetals

Transition Metals and Coordination Chemistry

The Chemistry of Life: Organic and Biological Chemistry

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Consider the reaction: Ag⁺ (aq) + Cl^- (aq) → AgCl (s) Given the following table of thermodynamic data at 298 K: The value of K for the reaction at 25 °C is ________.

The value of ΔS° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO₂(g) → S (s, rhombic) + O₂(g) Is ________ J/K ∙ mol.

The value of ΔG° at 181.0 °C for the formation of calcium chloride from its constituent elements: Ca (s)+ Cl₂ (g) → CaCl₂ (s) Is ________ kJ/mol. At 25.0 °C for this reaction, ΔH° is -795.8 kJ/mol, ΔG° is -748.1 kJ/mol, and ΔS° is -159.8 J/K.

For the reaction C(s) + H₂O(g) → CO(g) + H₂(g) ΔH° = 133.3 kJ/mol and ΔS° = 121.6 J/K ∙ mol at 298 K. At temperatures greater than ________ °C this reaction is spontaneous under standard conditions.

The combustion of ethene in the presence of excess oxygen yields carbon dioxide and water: C₂H₄ (g) + 3O₂ (g) → 2CO₂ (g) + 2H₂O (l) The value of ΔS° for this reaction is ________ J/K ∙ mol.

The value of ΔH° for the decomposition of POCl₃ into its constituent elements, 2POCl₃ (g) → P₂ (g) + O₂ (g) + 3Cl₂ (g) Is ________ kJ/mol.

Given the following table of thermodynamic data, complete the following sentence. The vaporization of PCl₃ (l)is ________.

The value of ΔG° at 25 °C for the decomposition of calcium chloride into its constituent elements, CaCl₂(s) → Ca (s) + Cl₂ (g) Is ________ kJ/mol.

For the reaction 2 C₄H₁₀ (g) + 13 O₂ (g)→ 8 CO₂ (g) + 10 H₂O (g) ΔH° is -125 kJ/mol and ΔS° is +253 J/K ∙ mol. This reaction is ________.