Question 1

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 A

Question 2

ΔS is negative for the reaction __________.

Accepted Answer

A) 2H2O (g)→ 2H2 (g)+ O2 (g) 
B) Mg(NO3)2 (aq)+ 2NaOH(aq)→ Mg(OH)2 (s)+ 2NaNO3 (aq) 
C) H2O (l)→ H2O (g) 
D) C6H12O6 (s)→ 6C (s)+ 6H2 (g)+ 3O2 (g) 
E) NaCl (aq)→ Na+ (aq)+ Cl- (aq) 
A) 2H2O (g)→ 2H2 (g)+ O2 (g) 
B) Mg(NO3)2 (aq)+ 2NaOH(aq)→ Mg(OH)2 (s)+ 2NaNO3 (aq) 
C) H2O (l)→ H2O (g) 
D) C6H12O6 (s)→ 6C (s)+ 6H2 (g)+ 3O2 (g) 
E) NaCl (aq)→ Na+ (aq)+ Cl- (aq) B

Question 3

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

Accepted Answer

A) 4 NH3 (g)+ 5 O2 (g)→ 4 NO (g)+ 6 H2O (g) 
B) Na (s)+ 1/2Cl2 (g)→ NaCl (s) 
C) 2 HgO (s)→ 2 Hg (l)+ O2 (g) 
D) U (s)+ 3F2 (g)→ UF6 (s) 
E) H2O (s)→ H2O (g) 
A) 4 NH3 (g)+ 5 O2 (g)→ 4 NO (g)+ 6 H2O (g) 
B) Na (s)+ 1/2Cl2 (g)→ NaCl (s) 
C) 2 HgO (s)→ 2 Hg (l)+ O2 (g) 
D) U (s)+ 3F2 (g)→ UF6 (s) 
E) H2O (s)→ H2O (g) B

Question 4

The value of ΔG° at 141.0°C for the formation of phosphorous trichloride from its constituent elements, P2 (g)+ 3Cl2 (g)→ 2PCl3 (g)
Is __________ kJ/mol. At 25.0°C for this reaction, ΔH° is -720.5 kJ/mol, ΔG° is -642.9 kJ/mol, and ΔS° is -263.7 J/K.

Accepted Answer

A) -612.3 
B) 3.65 × 104 
C) 1.08 × 105 
D) -683.3 
E) -829.7 
A) -612.3 
B) 3.65 × 104 
C) 1.08 × 105 
D) -683.3 
E) -829.7

Question 5

Of the following, the entropy of __________ is the largest.

Accepted Answer

A) H2O (s) 
B) H2O (l) 
C) H2O (g) 
D) H2S (g) 
E) H2S (l) 
A) H2O (s) 
B) H2O (l) 
C) H2O (g) 
D) H2S (g) 
E) H2S (l)

Question 6

ΔS is positive for the reaction __________.

Accepted Answer

A) Pb(NO3)2 (aq)+ 2KI(aq)→ PbI2 (s)+ 2KNO3 (aq) 
B) 2H2O (g)→ 2H2 (g)+ O2 (g) 
C) H2O (g)→ H2O (s) 
D) NO (g)+ O2 (g)→ NO2 (g) 
E) Ag+ (aq)+ Cl- (aq)→ AgCl (s) 
A) Pb(NO3)2 (aq)+ 2KI(aq)→ PbI2 (s)+ 2KNO3 (aq) 
B) 2H2O (g)→ 2H2 (g)+ O2 (g) 
C) H2O (g)→ H2O (s) 
D) NO (g)+ O2 (g)→ NO2 (g) 
E) Ag+ (aq)+ Cl- (aq)→ AgCl (s)

Question 7

The standard Gibbs free energy of formation of __________ is zero. (a)H2O (l)
(b)Mg (s)
(c)Br2 (l)

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 8

For a reaction to be spontaneous under standard conditions at all temperatures, the signs of ΔH° and ΔS° must be __________ and __________, respectively.

Accepted Answer

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

Question 9

If ΔG° for a reaction is greater than zero, then __________.

Accepted Answer

A) K = 0 B) K = 1 C) K > 1 D) K < 1 E) More information is needed. A) K = 0 B) K = 1 C) K > 1 D) K < 1 E) More information is needed.

Question 10

The value of ΔG° at 25°C for the formation of POCl3 from its constituent elements, P2 (g)+ O2 (g)+ 3Cl2 (g)→ 2POCl3 (g)
Is __________ kJ/mol.

Accepted Answer

A) -1108.7 
B) +1108.7 
C) -606.2 
D) +606.2 
E) -1,005 
A) -1108.7 
B) +1108.7 
C) -606.2 
D) +606.2 
E) -1,005

Question 11

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

Accepted Answer

A) +0.0 
B) +135.0 
C) -135.90 
D) -269.9 
E) +269.9 
A) +0.0 
B) +135.0 
C) -135.90 
D) -269.9 
E) +269.9

Question 12

The entropy change accompanying any process is given by the equation:

Accepted Answer

A) ΔS = k lnWfinal 
B) ΔS = k Wfinal - k Winitial 
C) ΔS = k ln(Wfinal / Winitial) 
D) ΔS = k final - k initial 
E) ΔS = Wfinal - Winitial 
A) ΔS = k lnWfinal 
B) ΔS = k Wfinal - k Winitial 
C) ΔS = k ln(Wfinal / Winitial) 
D) ΔS = k final - k initial 
E) ΔS = Wfinal - Winitial

Question 13

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 14

The value of ΔG° at 25°C for the formation of calcium chloride from its constituent elements, Ca (s)+ Cl2 (g)→ CaCl2 (s)
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 15

The melting of a substance at its melting point is an isothermal process.

Accepted Answer

A) True 
 B)False

Question 16

The value of ΔG° for a reaction conducted at 25°C is 3.05 kJ/mol. The equilibrium constant for a reaction is __________ at this temperature?

Accepted Answer

A) 0.292 
B) -4.20 
C) 0.320 
D) -1.13 
E) More information is needed. 
A) 0.292 
B) -4.20 
C) 0.320 
D) -1.13 
E) More information is needed.

Question 17

Calculate ΔG° (in kJ/mol)for the following reaction at 1 atm and 25°C:
C2H6 (g)+ O2 (g)→ CO2 (g)+ H2O (l)(unbalanced)
ΔGf° C2H6 (g)= -32.89 kJ/mol; ΔGf° CO2 (g)= -394.4 kJ/mol; ΔGf° H2O (l)= -237.13 kJ/mol

Accepted Answer

Question 18

The entropy of a pure crystalline substance at 0°C is zero.

Accepted Answer

A) True 
 B)False

Question 19

The standard Gibbs free energy of formation of __________ is zero. (a)Si (s)
(b)F2 (g)
(c)Ni (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 quantity of energy gained by a system equals the quantity of energy gained by its surroundings.

Accepted Answer

A) True 
 B)False

Exam 19: Chemical Thermodynamics

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

ΔS is negative for the reaction __________.

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

The value of ΔG° at 141.0°C for the formation of phosphorous trichloride from its constituent elements, P2 (g)+ 3Cl2 (g)→ 2PCl3 (g) Is __________ kJ/mol. At 25.0°C for this reaction, ΔH° is -720.5 kJ/mol, ΔG° is -642.9 kJ/mol, and ΔS° is -263.7 J/K.

Of the following, the entropy of __________ is the largest.

ΔS is positive for the reaction __________.

The standard Gibbs free energy of formation of __________ is zero. (a)H2O (l) (b)Mg (s) (c)Br2 (l)

For a reaction to be spontaneous under standard conditions at all temperatures, the signs of ΔH° and ΔS° must be __________ and __________, respectively.

If ΔG° for a reaction is greater than zero, then __________.

The value of ΔG° at 25°C for the formation of POCl3 from its constituent elements, P2 (g)+ O2 (g)+ 3Cl2 (g)→ 2POCl3 (g) Is __________ kJ/mol.

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

The entropy change accompanying any process is given by the equation:

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 formation of calcium chloride from its constituent elements, Ca (s)+ Cl2 (g)→ CaCl2 (s) Is __________ kJ/mol.

The melting of a substance at its melting point is an isothermal process.

The value of ΔG° for a reaction conducted at 25°C is 3.05 kJ/mol. The equilibrium constant for a reaction is __________ at this temperature?

Calculate ΔG° (in kJ/mol)for the following reaction at 1 atm and 25°C: C2H6 (g)+ O2 (g)→ CO2 (g)+ H2O (l)(unbalanced) ΔGf° C2H6 (g)= -32.89 kJ/mol; ΔGf° CO2 (g)= -394.4 kJ/mol; ΔGf° H2O (l)= -237.13 kJ/mol

The entropy of a pure crystalline substance at 0°C is zero.

The standard Gibbs free energy of formation of __________ is zero. (a)Si (s) (b)F2 (g) (c)Ni (s)

The quantity of energy gained by a system equals the quantity of energy gained by its surroundings.

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

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

The value of ΔG° at 141.0°C for the formation of phosphorous trichloride from its constituent elements, P₂ (g)+ 3Cl₂ (g)→ 2PCl₃ (g) Is __________ kJ/mol. At 25.0°C for this reaction, ΔH° is -720.5 kJ/mol, ΔG° is -642.9 kJ/mol, and ΔS° is -263.7 J/K.

The standard Gibbs free energy of formation of __________ is zero. (a)H₂O (l) (b)Mg (s) (c)Br₂ (l)

For a reaction to be spontaneous under standard conditions at all temperatures, the signs of ΔH° and ΔS° must be and , respectively.

The value of ΔG° at 25°C for the formation of POCl₃ from its constituent elements, P₂ (g)+ O₂ (g)+ 3Cl₂ (g)→ 2POCl₃ (g) Is __________ kJ/mol.

The value of ΔH° for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen, SO₂ (g)→ S (s,rhombic)+ O₂ (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 formation of calcium chloride from its constituent elements, Ca (s)+ Cl₂(g)→ CaCl₂(s) Is __________ kJ/mol.

Calculate ΔG°(in kJ/mol)for the following reaction at 1 atm and 25°C: C₂H₆ (g)+ O₂ (g)→ CO₂ (g)+ H₂O (l)(unbalanced) ΔG_f° C₂H₆ (g)= -32.89 kJ/mol; ΔG_f°CO₂ (g)= -394.4 kJ/mol; ΔG_f° H₂O (l)= -237.13 kJ/mol

The standard Gibbs free energy of formation of __________ is zero. (a)Si (s) (b)F₂ (g) (c)Ni (s)