Question 1

Consider the reaction: 
 
What is ΔG° for this reaction at 591 K? Is the reaction spontaneous at 591 K?

Accepted Answer

A)  -196 kJ/mol, no 
B)  196 kJ/mol, yes 
C)  196 kJ/mol, no 
D)  239 kJ/mol, yes 
E)  -239 kJ/mol, no 
A)  -196 kJ/mol, no 
B)  196 kJ/mol, yes 
C)  196 kJ/mol, no 
D)  239 kJ/mol, yes 
E)  -239 kJ/mol, no

Question 2

What is ΔG°rxn? 
2 O3(g) → 3 O2(g)  &emsp;ΔGf° (J/mol K) 163.2 0

Accepted Answer

A)  326.2 kJ 
B)  -326.4 kJ 
C)  -163.2 kJ 
D)  163.2 kJ 
E)  54.4 kJ 
A)  326.2 kJ 
B)  -326.4 kJ 
C)  -163.2 kJ 
D)  163.2 kJ 
E)  54.4 kJ

Question 3

For the reaction SO2(g) + Cl2(g) → SO2Cl2(g) Keq = 0.377 at 25°C, what is ΔG° for the reaction?

Accepted Answer

A)  202.7 J/mol 
B)  88.02 J/mol 
C)  2420 J/mol 
D)  1049 J/mol 
E)  -1049 J/mol 
A)  202.7 J/mol 
B)  88.02 J/mol 
C)  2420 J/mol 
D)  1049 J/mol 
E)  -1049 J/mol

Question 4

Calculate the temperature for which Keq for a reaction is 1.04 × 103 where ΔH° = -83.2 kJ/mol and ΔS° = -246 J/mol ∙ K.

Accepted Answer

A)  0.274 K 
B)  307 K 
C)  0.307 K 
D)  274 K 
E)  cannot be determined without ΔG° 
A)  0.274 K 
B)  307 K 
C)  0.307 K 
D)  274 K 
E)  cannot be determined without ΔG°

Question 5

Entropy is related to the way in which the energy of a system is distributed among the available microscopic energy levels.

Accepted Answer

A) True 
 B)False

Question 6

Choose the INCORRECT statement.

Accepted Answer

A)  One form of the second law of thermodynamics is all spontaneous processes produce an increase in the entropy of the universe. 
B)  Gibbs energy is defined by: G = H - TS. 
C)  If ΔG  0, the process is nonspontaneous. 
E)  If ΔG = 0, the process is spontaneous. 
A)  One form of the second law of thermodynamics is all spontaneous processes produce an increase in the entropy of the universe. 
B)  Gibbs energy is defined by: G = H - TS. 
C)  If ΔG  0, the process is nonspontaneous. 
E)  If ΔG = 0, the process is spontaneous.

Question 7

ΔG∘ is independent of temperature.

Accepted Answer

A) True 
 B)False

Question 8

The change in Gibbs energy for a reaction:

Accepted Answer

A)  = ΔH - TΔS 
B)  = Q (heat) 
C)  = ΔS + TΔH 
D)  = ΔS - TΔH 
E)  = ΔH + TΔS 
A)  = ΔH - TΔS 
B)  = Q (heat) 
C)  = ΔS + TΔH 
D)  = ΔS - TΔH 
E)  = ΔH + TΔS

Question 9

A spontaneous process will occur only if a some external action is continually applied.

Accepted Answer

A) True 
 B)False

Question 10

For the reaction PCl5(g) → PCl3(g) + Cl2(g) at 298 K, Keq = 1.87 × 10-7, ΔS° = 1.8192 J/(mol ∙K), what is ΔG° and is the reaction spontaneous?

Accepted Answer

A)  3.84 × 104 kJ/mol, no 
B)  7.68 kJ/mol, no 
C)  -7.68 kJ/mol, yes 
D)  38.4 kJ/mol, no 
E)  -38.4 kJ/mol, yes 
A)  3.84 × 104 kJ/mol, no 
B)  7.68 kJ/mol, no 
C)  -7.68 kJ/mol, yes 
D)  38.4 kJ/mol, no 
E)  -38.4 kJ/mol, yes

Question 11

Consider the following reaction: C3H4(g) + 2 H2(g) → C3H8(g)  &emsp; S° 266.9 130.6 269.9 J/mol∙deg
What is ΔS° in J/mol∙deg?

Accepted Answer

A)  127.6 J/mol∙deg 
B)  -127.6 J/mol∙deg 
C)  3.0 J/mol∙deg 
D)  -258.2 J/mol∙deg 
E)  -3.0 J/mol∙deg 
A)  127.6 J/mol∙deg 
B)  -127.6 J/mol∙deg 
C)  3.0 J/mol∙deg 
D)  -258.2 J/mol∙deg 
E)  -3.0 J/mol∙deg

Question 12

Consider the reaction: AB(g) → A(g) + B(g) (Keq = 0.729 at 20°C ΔH° = 45.9 kJ/mol)
What is Keq for this reaction at 425 K?

Accepted Answer

A)  476 
B)  0.733 
C)  0.725 
D)  253 
E)  2.10 × 10-3 
A)  476 
B)  0.733 
C)  0.725 
D)  253 
E)  2.10 × 10-3

Question 13

Consider the following reaction:
  &emsp; S2Cl2(g) + 2 OCl2(g) → 2 SOCl2(g) + Cl2(g)
ΔG°f -32  &emsp;  &emsp; 97.9   &emsp;  &emsp;  &emsp;-320  &emsp;  &emsp;  &emsp; 0.0 kJ/mol
What is Keq for this reaction at 25 °C?

Accepted Answer

A)  e324 
B)  e-324 
C)  e162 
D)  e-162 
E)  1.38 
A)  e324 
B)  e-324 
C)  e162 
D)  e-162 
E)  1.38

Question 14

What is ΔG°rxn? N2O4(g) → 2 NO2(g)  &emsp; ΔGf° (J/mol K) 97.8 51.3

Accepted Answer

A)  149.1 kJ 
B)  -4.8 kJ 
C)  -46.5 kJ 
D)  4.8 kJ 
E)  46.5 kJ 
A)  149.1 kJ 
B)  -4.8 kJ 
C)  -46.5 kJ 
D)  4.8 kJ 
E)  46.5 kJ

Question 15

ΔG is positive for a spontaneous reaction.

Accepted Answer

A) True 
 B)False

Question 16

Which of the following has the largest molar entropy?

Accepted Answer

A)  I2(g) 
B)  Xe(g) 
C)  H2(g) 
D)  He(g) 
A)  I2(g) 
B)  Xe(g) 
C)  H2(g) 
D)  He(g)

Question 17

Which of the following quantities for an element has a value of zero in the standard state? I) ΔH°f
II) ΔG°f
III) S°

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  I, II, and III 
A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  I, II, and III

Question 18

For the reaction: CO(g) + 2 H2(g) → CH3OH(g) Kp = 91.4 at 350 K and Kp = 2.05 × 10-4 at 298 K.
What is the value of ΔH°?

Accepted Answer

A)  49.9 kJ/mol 
B)  2.08 × 103 kJ/mol 
C)  3.74 × 10-2 kJ/mol 
D)  217 kJ/mol 
E)  446 kJ/mol 
A)  49.9 kJ/mol 
B)  2.08 × 103 kJ/mol 
C)  3.74 × 10-2 kJ/mol 
D)  217 kJ/mol 
E)  446 kJ/mol

Question 19

Consider the reaction of 25.0 mL of 0.20 M AgNO3(aq) with 25.0 mL of 0.20 M NaBr(aq) to form AgBr(s) at 25°C. What is ΔG for this reaction? The Ksp of AgBr is 5.0 x 10-13 at 25°C.

Accepted Answer

A)  -58.8 kJ/mol 
B)  -70.2 kJ/mol 
C)  +58.8 kJ/mol 
D)  +70.2 kJ/mol 
A)  -58.8 kJ/mol 
B)  -70.2 kJ/mol 
C)  +58.8 kJ/mol 
D)  +70.2 kJ/mol

Question 20

Choose the correct statements concerning entropy. I) As two gasses mix, ΔS is positive.
II) Entropy is a thermodynamic property related to the degree of disorder.
III) As temperature in a gas decreases, ΔS is positive.
IV) Molecules in the liquid state have higher entropy than molecules in the gaseous state.

Accepted Answer

A)  I and III 
B)  I, II, III 
C)  I and II 
D)  I, II, IV 
E)  II and III 
A)  I and III 
B)  I, II, III 
C)  I and II 
D)  I, II, IV 
E)  II and III

Exam 19: Spontaneous Change: Entropy and Free Energy

Consider the reaction: What is ΔG° for this reaction at 591 K? Is the reaction spontaneous at 591 K?

What is ΔG°rxn? 2 O3(g) → 3 O2(g) ΔGf° (J/mol K) 163.2 0

For the reaction SO2(g) + Cl2(g) → SO2Cl2(g) Keq = 0.377 at 25°C, what is ΔG° for the reaction?

Calculate the temperature for which Keq for a reaction is 1.04 × 103 where ΔH° = -83.2 kJ/mol and ΔS° = -246 J/mol ∙ K.

Entropy is related to the way in which the energy of a system is distributed among the available microscopic energy levels.

Choose the INCORRECT statement.

ΔG∘ is independent of temperature.

The change in Gibbs energy for a reaction:

A spontaneous process will occur only if a some external action is continually applied.

For the reaction PCl5(g) → PCl3(g) + Cl2(g) at 298 K, Keq = 1.87 × 10-7, ΔS° = 1.8192 J/(mol ∙K), what is ΔG° and is the reaction spontaneous?

Consider the following reaction: C3H4(g) + 2 H2(g) → C3H8(g) S° 266.9 130.6 269.9 J/mol∙deg What is ΔS° in J/mol∙deg?

Consider the reaction: AB(g) → A(g) + B(g) (Keq = 0.729 at 20°C ΔH° = 45.9 kJ/mol) What is Keq for this reaction at 425 K?

Consider the following reaction: S2Cl2(g) + 2 OCl2(g) → 2 SOCl2(g) + Cl2(g) ΔG°f -32 97.9 -320 0.0 kJ/mol What is Keq for this reaction at 25 °C?

What is ΔG°rxn? N2O4(g) → 2 NO2(g) ΔGf° (J/mol K) 97.8 51.3

ΔG is positive for a spontaneous reaction.

Which of the following has the largest molar entropy?

Which of the following quantities for an element has a value of zero in the standard state? I) ΔH°f II) ΔG°f III) S°

For the reaction: CO(g) + 2 H2(g) → CH3OH(g) Kp = 91.4 at 350 K and Kp = 2.05 × 10-4 at 298 K. What is the value of ΔH°?

Consider the reaction of 25.0 mL of 0.20 M AgNO3(aq) with 25.0 mL of 0.20 M NaBr(aq) to form AgBr(s) at 25°C. What is ΔG for this reaction? The Ksp of AgBr is 5.0 x 10-13 at 25°C.

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

What is ΔG°rxn? 2 O₃(g) → 3 O₂(g) ΔGf° (J/mol K) 163.2 0

For the reaction SO₂(g) + Cl₂(g) → SO₂Cl₂(g) Keq = 0.377 at 25°C, what is ΔG° for the reaction?

Calculate the temperature for which Keq for a reaction is 1.04 × 10³ where ΔH° = -83.2 kJ/mol and ΔS° = -246 J/mol ∙ K.

For the reaction PCl₅(g) → PCl₃(g) + Cl₂(g) at 298 K, Keq = 1.87 × 10^-7, ΔS° = 1.8192 J/(mol ∙K), what is ΔG° and is the reaction spontaneous?

Consider the following reaction: C₃H₄(g) + 2 H₂(g) → C₃H₈(g) S° 266.9 130.6 269.9 J/mol∙deg What is ΔS° in J/mol∙deg?

Consider the following reaction: S₂Cl₂(g) + 2 OCl₂(g) → 2 SOCl₂(g) + Cl₂(g) ΔG°f -32 97.9 -320 0.0 kJ/mol What is Keq for this reaction at 25 °C?

What is ΔG°rxn? N₂O₄(g) → 2 NO₂(g) ΔGf° (J/mol K) 97.8 51.3

For the reaction: CO(g) + 2 H₂(g) → CH₃OH(g) Kp = 91.4 at 350 K and Kp = 2.05 × 10^-4 at 298 K. What is the value of ΔH°?

Consider the reaction of 25.0 mL of 0.20 M AgNO₃(aq) with 25.0 mL of 0.20 M NaBr(aq) to form AgBr(s) at 25°C. What is ΔG for this reaction? The Ksp of AgBr is 5.0 x 10^-13 at 25°C.