Question 1

ΔS is positive for the reaction __________.

Accepted Answer

A) 2 Ca (s)+ O2 (g)→ 2 CaO (s) 
B) 2 KClO3 (s)→ 2KCl (s)+ 3 O2 (g) 
C) HCl (g)+ NH3 (g)→ NH4Cl (s) 
D) Pb+2 (aq)+ 2Cl- (aq)→ PbCl2 (s) 
E) CO2 (g)→ CO2 (s) 
A) 2 Ca (s)+ O2 (g)→ 2 CaO (s) 
B) 2 KClO3 (s)→ 2KCl (s)+ 3 O2 (g) 
C) HCl (g)+ NH3 (g)→ NH4Cl (s) 
D) Pb+2 (aq)+ 2Cl- (aq)→ PbCl2 (s) 
E) CO2 (g)→ CO2 (s)

Question 2

The combustion of ethane in the presence of excess oxygen yields carbon dioxide and water: 2C2H6 (g)+ 7O2 (g)→ 4CO2 (g)+ 6H2O (l)
The value of ΔS° for this reaction is __________ J/K∙ mol.

Accepted Answer

A) +718.0 
B) -620.1 
C) -718.0 
D) -151.0 
E) +151.0 
A) +718.0 
B) -620.1 
C) -718.0 
D) -151.0 
E) +151.0

Question 3

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 4

ΔS is positive for the reaction __________.

Accepted Answer

A) 2H2 (g)+ O2 (g)→ 2H2O (g) 
B) 2NO2 (g)→ N2O4 (g) 
C) CO2 (g)→ CO2 (s) 
D) BaF2 (s)→ Ba2+ (aq)+ 2F- (aq) 
E) 2Hg (l)+ O2 (g)→ 2HgO (s) 
A) 2H2 (g)+ O2 (g)→ 2H2O (g) 
B) 2NO2 (g)→ N2O4 (g) 
C) CO2 (g)→ CO2 (s) 
D) BaF2 (s)→ Ba2+ (aq)+ 2F- (aq) 
E) 2Hg (l)+ O2 (g)→ 2HgO (s)

Question 5

The value of ΔS° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic)+ 3O2(g)→ 2SO3 (g)
Is __________ J/K∙ mol.

Accepted Answer

A) +19.3 
B) -19.3 
C) +493.1 
D) -166.4 
E) -493.1 
A) +19.3 
B) -19.3 
C) +493.1 
D) -166.4 
E) -493.1

Question 6

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 7

The value of ΔS° for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen, 2SO3 (g)→ 2S (s, rhombic)+ 3O2 (g)
Is __________ J/K∙ mol.

Accepted Answer

A) +19.3 
B) -19.3 
C) +493.1 
D) +166.4 
E) -493.1 
A) +19.3 
B) -19.3 
C) +493.1 
D) +166.4 
E) -493.1

Question 8

The value of ΔH° for the formation of phosphorous trichloride from its constituent elements, P2 (g)+ 3Cl2 (g)→ 2PCl3 (g)
Is __________ kJ/mol

Accepted Answer

A) -288.1 
B) +432.4 
C) -720.5 
D) +720.5 
E) -432.4 
A) -288.1 
B) +432.4 
C) -720.5 
D) +720.5 
E) -432.4

Question 9

With thermodynamics, one cannot determine __________.

Accepted Answer

A) the speed of a reaction 
B) the direction of a spontaneous reaction 
C) the extent of a reaction 
D) the value of the equilibrium constant 
E) the temperature at which a reaction will be spontaneous 
A) the speed of a reaction 
B) the direction of a spontaneous reaction 
C) the extent of a reaction 
D) the value of the equilibrium constant 
E) the temperature at which a reaction will be spontaneous

Question 10

Which reaction produces a decrease in the entropy of the system?

Accepted Answer

A) CaCO3 (s)→ CaO (s)+ CO2 (g) 
B) 2C (s)+ O2 (g)→ 2CO (g) 
C) CO2 (s)→ CO2 (g) 
D) 2H2 (g)+ O2 (g)→ 2H2O (l) 
E) H2O (l)→ H2O (g) 
A) CaCO3 (s)→ CaO (s)+ CO2 (g) 
B) 2C (s)+ O2 (g)→ 2CO (g) 
C) CO2 (s)→ CO2 (g) 
D) 2H2 (g)+ O2 (g)→ 2H2O (l) 
E) H2O (l)→ H2O (g)

Question 11

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 12

For a given reaction, ΔH = -19.9 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) 359 
B) 2789 
C) 298 
D) 2.79 
E) 0.359 
A) 359 
B) 2789 
C) 298 
D) 2.79 
E) 0.359

Question 13

The entropy of the universe is __________.

Accepted Answer

A) constant 
B) continually decreasing 
C) continually increasing 
D) zero 
E) the same as the energy, E 
A) constant 
B) continually decreasing 
C) continually increasing 
D) zero 
E) the same as the energy, E

Question 14

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 15

The value of ΔG° at 25°C for the decomposition of phosphorous trichloride into its constituent elements, 2PCl3 (g)→ P2 (g)+ 3Cl2 (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 16

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 17

Consider the reaction: Ag+ (aq)+ Cl- (aq)→ AgCl (s)
Given the following table of thermodynamic data,   determine the temperature (in °C)above which the reaction is nonspontaneous under standard conditions.

Accepted Answer

A) 1230 
B) 150 
C) 432 
D) 133 
E) 1640 
A) 1230 
B) 150 
C) 432 
D) 133 
E) 1640

Question 18

ΔS is positive for the reaction __________.

Accepted Answer

A) 2NO (g)+ O2 (g)→ 2NO2 (g) 
B) 2N2 (g)+ 3H2 (g)→ 2 NH3 (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)→ 2 NH3 (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 19

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

Accepted Answer

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

Question 20

The normal boiling point of C2Cl3F3 is 47.6°C and its molar enthalpy of vaporization is 27.49 kJ/mol. What is the change in entropy in the system in J/K when 24.1 grams of C2Cl3F3 vaporizes to a gas at the normal boiling point?

Accepted Answer

A) -11.0 
B) -4.19 
C) 4.19 
D) 11.0 
E) 27.5 
A) -11.0 
B) -4.19 
C) 4.19 
D) 11.0 
E) 27.5

Exam 19: Chemical Thermodynamics

ΔS is positive for the reaction __________.

The combustion of ethane in the presence of excess oxygen yields carbon dioxide and water: 2C2H6 (g)+ 7O2 (g)→ 4CO2 (g)+ 6H2O (l) The value of ΔS° for this reaction is __________ J/K∙ mol.

A reversible process is one that __________.

ΔS is positive for the reaction __________.

The value of ΔS° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic)+ 3O2(g)→ 2SO3 (g) Is __________ J/K∙ mol.

A reaction that is spontaneous as written __________.

The value of ΔS° for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen, 2SO3 (g)→ 2S (s, rhombic)+ 3O2 (g) Is __________ J/K∙ mol.

The value of ΔH° for the formation of phosphorous trichloride from its constituent elements, P2 (g)+ 3Cl2 (g)→ 2PCl3 (g) Is __________ kJ/mol

With thermodynamics, one cannot determine __________.

Which reaction produces a decrease in the entropy of the system?

The value of ΔS° for the reaction 2C (s, diamond)+ O2 (g)→ 2CO (g) Is __________ J/K∙ mol.

For a given reaction, ΔH = -19.9 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 entropy of the universe is __________.

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 ΔG° at 25°C for the decomposition of phosphorous trichloride into its constituent elements, 2PCl3 (g)→ P2 (g)+ 3Cl2 (g) Is __________ kJ/mol.

ΔS is positive for the reaction __________.

Consider the reaction: Ag+ (aq)+ Cl- (aq)→ AgCl (s) Given the following table of thermodynamic data, determine the temperature (in °C)above which the reaction is nonspontaneous under standard conditions.

ΔS is positive for the reaction __________.

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

The normal boiling point of C2Cl3F3 is 47.6°C and its molar enthalpy of vaporization is 27.49 kJ/mol. What is the change in entropy in the system in J/K when 24.1 grams of C2Cl3F3 vaporizes to a gas at the normal boiling point?

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

The combustion of ethane in the presence of excess oxygen yields carbon dioxide and water: 2C₂H₆ (g)+ 7O₂ (g)→ 4CO₂ (g)+ 6H₂O (l) The value of ΔS° for this reaction is __________ J/K∙ mol.

The value of ΔS° for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic)+ 3O₂(g)→ 2SO₃ (g) Is __________ J/K^∙ mol.

The value of ΔS° for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen, 2SO₃ (g)→ 2S (s, rhombic)+ 3O₂ (g) Is __________ J/K∙ mol.

The value of ΔH° for the formation of phosphorous trichloride from its constituent elements, P₂ (g)+ 3Cl₂ (g)→ 2PCl₃(g) Is __________ kJ/mol

The value of ΔS° for the reaction 2C (s, diamond)+ O₂ (g)→ 2CO (g) Is __________ J/K∙ mol.

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 ΔG° at 25°C for the decomposition of phosphorous trichloride into its constituent elements, 2PCl₃ (g)→ P₂ (g)+ 3Cl₂ (g) Is __________ kJ/mol.

Consider the reaction: Ag⁺ (aq)+ Cl^- (aq)→ AgCl (s) Given the following table of thermodynamic data, determine the temperature (in °C)above which the reaction is nonspontaneous under standard conditions.

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

The normal boiling point of C₂Cl₃F₃ is 47.6°C and its molar enthalpy of vaporization is 27.49 kJ/mol. What is the change in entropy in the system in J/K when 24.1 grams of C₂Cl₃F₃ vaporizes to a gas at the normal boiling point?