Question 1

ΔS is positive for the reaction ________.

Accepted Answer

A) 2NO (g) + O2 (g) → 2NO2 (g) 
B) 2N2 (g) + 3H2 (g) → 2NH3 (g) 
C) C3H8 (g) + 5 O2 (g) → 3CO2 (g) + 4 H2O (g) 
D) Mg (s) + Cl2 (g) → MgCl2 (s) 
E) C2H4 (g) + H2 (g) → C2H6 (g) 
A) 2NO (g) + O2 (g) → 2NO2 (g) 
B) 2N2 (g) + 3H2 (g) → 2NH3 (g) 
C) C3H8 (g) + 5 O2 (g) → 3CO2 (g) + 4 H2O (g) 
D) Mg (s) + Cl2 (g) → MgCl2 (s) 
E) C2H4 (g) + H2 (g) → C2H6 (g)

Question 2

For the reaction C2H6 (g) → C2H4 (g) + H2 (g)
ΔH° is +137 kJ/mol and ΔS° is +120 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 
A) spontaneous at all temperatures 
B) spontaneous only at high temperature 
C) spontaneous only at low temperature 
D) nonspontaneous at all temperatures

Question 3

The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction)below?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 4

ΔS is negative for the reaction ________.

Accepted Answer

A) Sr(NO3)2 (aq) + 2LiOH (aq) → Sr(OH)2 (s)+ 2LiNO3 (aq) 
B) 2H2O (g) → 2H2 (g) + O2 (g) 
C) CH3OH (l)→ CH3OH (g) 
D) LiOH (aq)→ Li+ (aq)+ OH- (aq) 
E) C6H12O6 (s) → 6C (s)+ 6H2 (g)+ 3O2 (g) 
A) Sr(NO3)2 (aq) + 2LiOH (aq) → Sr(OH)2 (s)+ 2LiNO3 (aq) 
B) 2H2O (g) → 2H2 (g) + O2 (g) 
C) CH3OH (l)→ CH3OH (g) 
D) LiOH (aq)→ Li+ (aq)+ OH- (aq) 
E) C6H12O6 (s) → 6C (s)+ 6H2 (g)+ 3O2 (g)

Question 5

The thermodynamic quantity that expresses the extent of randomness in a system is ________.

Accepted Answer

A) enthalpy 
B) internal energy 
C) bond energy 
D) entropy 
E) heat flow 
A) enthalpy 
B) internal energy 
C) bond energy 
D) entropy 
E) heat flow

Question 6

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 reaction 2C (s, diamond) + O2 (g) → 2CO (g)
Is ________ J/K ∙ mol.

Accepted Answer

A) -185.9 
B) +185.9 
C) -9.5 
D) +9.5 
E) -195.7 
A) -185.9 
B) +185.9 
C) -9.5 
D) +9.5 
E) -195.7

Question 7

The value of ΔS° for the formation of POCl3 from its constituent elements, P2 (g) + O2 (g) + 3Cl2 (g) → 2POCl3 (g)
Is ________ J/K ∙ mol.

Accepted Answer

A) -442.0 
B) +771.0 
C) -321.0 
D) -771.0 
E) +321.0 
A) -442.0 
B) +771.0 
C) -321.0 
D) -771.0 
E) +321.0

Question 8

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O2( g) → 2SO3 (g)
Is ________ kJ/mol.

Accepted Answer

A) +790.4 
B) -790.4 
C) +395.2 
D) -395.2 
E) +105.1 
A) +790.4 
B) -790.4 
C) +395.2 
D) -395.2 
E) +105.1

Question 9

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, S (s, rhombic) + O2 (g) → SO2 (g)
Is ________ kJ/mol.

Accepted Answer

A) +269.9 
B) -269.9 
C) +0.00 
D) -11.6 
E) +11.6 
A) +269.9 
B) -269.9 
C) +0.00 
D) -11.6 
E) +11.6

Question 10

A reaction that is spontaneous as written ________.

Accepted Answer

A) is very rapid 
B) will proceed without outside intervention 
C) is also spontaneous in the reverse direction 
D) has an equilibrium position that lies far to the left 
E) is very slow 
A) is very rapid 
B) will proceed without outside intervention 
C) is also spontaneous in the reverse direction 
D) has an equilibrium position that lies far to the left 
E) is very slow

Question 11

The value of ΔG° at 25 °C for the formation of phosphorous trichloride from its constituent elements, P2 (g) + 3Cl2 (g) → 2PCl3 (g)
Is ________ kJ/mol.

Accepted Answer

A) -539.2 
B) +539.2 
C) -642.9 
D) +642.9 
E) -373.3 
A) -539.2 
B) +539.2 
C) -642.9 
D) +642.9 
E) -373.3

Question 12

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is ________ and ΔS is ________.

Accepted Answer

A) +, + 
B) -, - 
C) +, - 
D) -, + 
E) +, 0 
A) +, + 
B) -, - 
C) +, - 
D) -, + 
E) +, 0

Question 13

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

Accepted Answer

A) 0.00 
B) -397.9 
C) +397.9 
D) -795.8 
E) +795.8 
A) 0.00 
B) -397.9 
C) +397.9 
D) -795.8 
E) +795.8

Question 14

Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K)for the reaction: 2 SO2 (g) + O2 (g)   2 SO3 (g)

Accepted Answer

A) 2.40 × 1024 
B) 1.06 
C) 1.95 
D) 3.82 × 1023 
E) More data are needed. 
A) 2.40 × 1024 
B) 1.06 
C) 1.95 
D) 3.82 × 1023 
E) More data are needed.

Question 15

Find the temperature (in K)above which a reaction with a ΔH of 123.0 kJ/mol and a ΔS of 90.00 J/K ∙ mol becomes spontaneous.

Accepted Answer

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

Question 16

The normal boiling point of water is 100.0 °C and its molar enthalpy of vaporization is 40.67 kJ/mol. What is the change in entropy in the system in J/K when 24.7 grams of steam at 1 atm condenses to a liquid at the normal boiling point?

Accepted Answer

A) 88.8 
B) -88.8 
C) -150 
D) 373 
E) -40.7 
A) 88.8 
B) -88.8 
C) -150 
D) 373 
E) -40.7

Question 17

For a given reaction, ΔH = -24.2 kJ/mol and ΔS = -55.5 J/K-mol. The reaction will have ΔG = 0 at ________K. Assume that ΔH and ΔS do not vary with temperature.

Accepted Answer

A) 436 
B) 2293 
C) 298 
D) 2.29 
E) 0.436 
A) 436 
B) 2293 
C) 298 
D) 2.29 
E) 0.436

Question 18

The value of ΔG° (kJ/mol)at 25 °C is -57.5. What is the equilibrium constant for this reaction at this temperature expressed with 2 significant digits?

Accepted Answer

A) 1.2 × 1010 
B) 10 
C) 1.0 
D) 8.4 × 10101 
E) more information is needed 
A) 1.2 × 1010 
B) 10 
C) 1.0 
D) 8.4 × 10101 
E) more information is needed

Question 19

The standard Gibbs free energy of formation of ________ is zero. (a) H2O (l)
(b) Fe (s)
(c) I2 (s)

Accepted Answer

A) (a)only 
B) (b)only 
C) (c)only 
D) (b)and (c) 
E) (a), (b), and (c) 
A) (a)only 
B) (b)only 
C) (c)only 
D) (b)and (c) 
E) (a), (b), and (c)

Question 20

The standard Gibbs free energy of formation of ________ is zero. (a) Mn (s)
(b) I2 (s)
(c) Cu (s)

Accepted Answer

A) (a)only 
B) (b)only 
C) (c)only 
D) (b)and (c) 
E) (a), (b), and (c) 
A) (a)only 
B) (b)only 
C) (c)only 
D) (b)and (c) 
E) (a), (b), and (c)

Exam 19: Chemical Thermodynamics

ΔS is positive for the reaction ________.

For the reaction C2H6 (g) → C2H4 (g) + H2 (g) ΔH° is +137 kJ/mol and ΔS° is +120 J/K ∙ mol. This reaction is ________.

The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction)below?

ΔS is negative for the reaction ________.

The thermodynamic quantity that expresses the extent of randomness in a system is ________.

The value of ΔS° for the formation of POCl3 from its constituent elements, P2 (g) + O2 (g) + 3Cl2 (g) → 2POCl3 (g) Is ________ J/K ∙ mol.

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O2( g) → 2SO3 (g) Is ________ kJ/mol.

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, S (s, rhombic) + O2 (g) → SO2 (g) Is ________ kJ/mol.

A reaction that is spontaneous as written ________.

The value of ΔG° at 25 °C for the formation of phosphorous trichloride from its constituent elements, P2 (g) + 3Cl2 (g) → 2PCl3 (g) Is ________ kJ/mol.

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is ________ and ΔS is ________.

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

Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K)for the reaction: 2 SO2 (g) + O2 (g) 2 SO3 (g)

Find the temperature (in K)above which a reaction with a ΔH of 123.0 kJ/mol and a ΔS of 90.00 J/K ∙ mol becomes spontaneous.

The normal boiling point of water is 100.0 °C and its molar enthalpy of vaporization is 40.67 kJ/mol. What is the change in entropy in the system in J/K when 24.7 grams of steam at 1 atm condenses to a liquid at the normal boiling point?

For a given reaction, ΔH = -24.2 kJ/mol and ΔS = -55.5 J/K-mol. The reaction will have ΔG = 0 at ________K. Assume that ΔH and ΔS do not vary with temperature.

The value of ΔG° (kJ/mol)at 25 °C is -57.5. What is the equilibrium constant for this reaction at this temperature expressed with 2 significant digits?

The standard Gibbs free energy of formation of ________ is zero. (a) H2O (l) (b) Fe (s) (c) I2 (s)

The standard Gibbs free energy of formation of ________ is zero. (a) Mn (s) (b) I2 (s) (c) Cu (s)

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

Filters

For the reaction C₂H₆ (g) → C₂H₄ (g) + H₂ (g) ΔH° is +137 kJ/mol and ΔS° is +120 J/K ∙ mol. This reaction is ________.

The value of ΔS° for the formation of POCl₃ from its constituent elements, P₂(g) + O₂ (g) + 3Cl₂ (g) → 2POCl₃ (g) Is ________ J/K ∙ mol.

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O₂( g) → 2SO₃ (g) Is ________ kJ/mol.

The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, S (s, rhombic) + O₂ (g) → SO₂ (g) Is ________ kJ/mol.

The value of ΔG° at 25 °C for the formation of phosphorous trichloride from its constituent elements, P₂(g) + 3Cl₂ (g) → 2PCl₃ (g) Is ________ kJ/mol.

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is and ΔS is .

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

Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K)for the reaction: 2 SO₂ (g) + O₂ (g) 2 SO₃ (g)

The standard Gibbs free energy of formation of ________ is zero. (a) H₂O (l) (b) Fe (s) (c) I₂ (s)

The standard Gibbs free energy of formation of ________ is zero. (a) Mn (s) (b) I₂ (s) (c) Cu (s)