Question 1

For the reaction, CaCO3(s) → CaO(s) + CO2(g) S° (J/mol K) 88.70 39.75 213.6
What is ΔS°rxn?

Accepted Answer

A)  262.5 J/mol ∙ K 
B)  -85.1 J/mol ∙ K 
C)  -164.7 J/mol ∙ K 
D)  164.7 J/mol ∙ K 
E)  85.1 J/mol ∙ K 
A)  262.5 J/mol ∙ K 
B)  -85.1 J/mol ∙ K 
C)  -164.7 J/mol ∙ K 
D)  164.7 J/mol ∙ K 
E)  85.1 J/mol ∙ K

Question 2

Which of the following has the highest entropy?

Accepted Answer

A)  1 mole of liquid water at 30°C 
B)  1 mole of water vapor at 30°C 
C)  1 mole of regular ice at -10°C 
D)  1 mole of "dry ice" at -10°C 
E)  1 mole of water under 10 atm of pressure at -10°C 
A)  1 mole of liquid water at 30°C 
B)  1 mole of water vapor at 30°C 
C)  1 mole of regular ice at -10°C 
D)  1 mole of "dry ice" at -10°C 
E)  1 mole of water under 10 atm of pressure at -10°C

Question 3

Which of the following processes would result in a decrease in system entropy?

Accepted Answer

A)  melting of an ice cube 
B)  sublimation of a moth ball 
C)  evaporation of a puddle of gasoline 
D)  a glass of cool lemonade warming in the sun 
E)  condensation of water vapor on a cold windshield 
A)  melting of an ice cube 
B)  sublimation of a moth ball 
C)  evaporation of a puddle of gasoline 
D)  a glass of cool lemonade warming in the sun 
E)  condensation of water vapor on a cold windshield

Question 4

If ΔG < 0 for a reaction, then the reaction is said to be:

Accepted Answer

A)  endothermic 
B)  reversible 
C)  spontaneous 
D)  exothermic 
E)  fast 
A)  endothermic 
B)  reversible 
C)  spontaneous 
D)  exothermic 
E)  fast

Question 5

What is ΔG° at 25 °C? 
CaCO3(s) → CaO(s) + CO2(g) &emsp; &emsp; ΔH° = 177.8 kJ &emsp; &emsp; ΔS° = 160.7 J/K

Accepted Answer

A)  1779 kJ 
B)  173.8 kJ 
C)  225.7 kJ 
D)  181.8 kJ 
E)  129.9 kJ 
A)  1779 kJ 
B)  173.8 kJ 
C)  225.7 kJ 
D)  181.8 kJ 
E)  129.9 kJ

Question 6

The Gibbs energy change for a reaction is -298 kJ. The reaction is therefore:

Accepted Answer

A)  exothermic 
B)  irreversible 
C)  spontaneous 
D)  endothermic 
E)  nonspontaneous 
A)  exothermic 
B)  irreversible 
C)  spontaneous 
D)  endothermic 
E)  nonspontaneous

Question 7

The fact that the entropies of vaporization for liquids which exhibit hydrogen bonding are greater than the 87 J/(mol ∙ K) which is expected of non-polar liquids is an exception to:

Accepted Answer

A)  the Gibb's Energy Rule 
B)  the Third Law of Thermodynamics 
C)  the Clausius-Clapyeron Rule 
D)  the Second Law of Thermodynamics 
E)  Trouton's Rule 
A)  the Gibb's Energy Rule 
B)  the Third Law of Thermodynamics 
C)  the Clausius-Clapyeron Rule 
D)  the Second Law of Thermodynamics 
E)  Trouton's Rule

Question 8

In a sealed container, the rate of dissolving is equal to the rate of crystallization. Therefore we would expect:

Accepted Answer

A)  ΔG  0 
C)  ΔG = 0 
D)  ΔS = 0 
E)  must know ΔH to determine 
A)  ΔG  0 
C)  ΔG = 0 
D)  ΔS = 0 
E)  must know ΔH to determine

Question 9

For CdO(s) + SO3(g) → CdSO4(s) ΔH° = -279.4 kJ/mol, and ΔS° = -118.4 J/mol-deg. What is the temperature at which Keq is 1.0 × 104?

Accepted Answer

A)  1890 °C 
B)  6950 °C 
C)  1160 °C 
D)  1710 °C 
E)  6410 °C 
A)  1890 °C 
B)  6950 °C 
C)  1160 °C 
D)  1710 °C 
E)  6410 °C

Question 10

Which of the following substances under equal conditions and in the same phase has the greatest molar entropy?

Accepted Answer

A)  NO 
B)  NO2 
C)  N2O3 
D)  N2O4 
E)  N2O5 
A)  NO 
B)  NO2 
C)  N2O3 
D)  N2O4 
E)  N2O5

Question 11

Consider the following reaction: C(g) + 2 H2(g) → CH4(g)  &emsp; S° 5.69 130.58 186.19 J/mol∙deg
What is ΔS° for the above reaction in J/mol∙deg?

Accepted Answer

A)  -49.9 J/mol∙deg 
B)  49.9 J/mol∙deg 
C)  80.7 J/mol∙deg 
D)  115.2 J/mol∙deg 
E)  -80.7 J/mol∙deg 
A)  -49.9 J/mol∙deg 
B)  49.9 J/mol∙deg 
C)  80.7 J/mol∙deg 
D)  115.2 J/mol∙deg 
E)  -80.7 J/mol∙deg

Question 12

Find correct statements. 
I. A spontaneous process is a process that occurs in a system left to itself.
II. A nonspontaneous process will not occur unless some external force is applied.
III. If a reaction is spontaneous, the reverse is also spontaneous.
IV. Only spontaneous processes occur naturally.
V. Entropy is inversely proportional to the degree of randomness.

Accepted Answer

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

Question 13

For the reaction N2O3(g) → NO(g) + NO2(g) ΔG° = -4.78. Calculate Keq at 25°C.

Accepted Answer

A)  1.023 
B)  1.002 
C)  1.005 
D)  0.9484 
E)  0.9981 
A)  1.023 
B)  1.002 
C)  1.005 
D)  0.9484 
E)  0.9981

Question 14

For CO(g) + H2(g) → H2CO(g)   &emsp; ΔH° = -5.36 kJ/mol, and ΔS° = -109.8 J/mol-deg. What is ΔG° in kJ/mol at 300 K?

Accepted Answer

A)  -38.3 kJ/mol 
B)  57.6 kJ/mol 
C)  38.3 kJ/mol 
D)  27.6 kJ/mol 
E)  -57.6 kJ/mol 
A)  -38.3 kJ/mol 
B)  57.6 kJ/mol 
C)  38.3 kJ/mol 
D)  27.6 kJ/mol 
E)  -57.6 kJ/mol

Question 15

The normal melting and boiling points of SO2 are 198 and 263 K, respectively. For a plot of the standard molar entropy of SO2 versus temperature, which of the following is INCORRECT?

Accepted Answer

A)  At 263 K, S° is constant. 
B)  S° increases with increasing temperature. 
C)  S° equals zero at 0 K. 
D)  At 198 K, S° increases by the value of △Sfusion. 
A)  At 263 K, S° is constant. 
B)  S° increases with increasing temperature. 
C)  S° equals zero at 0 K. 
D)  At 198 K, S° increases by the value of △Sfusion.

Question 16

A reaction is spontaneous if: 
I. ΔG is a negative value
II. both enthalpy and entropy increase
III. ΔH is negative and ΔS is positive
IV. both enthalpy and entropy decrease
V. ΔH is positive and ΔS is negative

Accepted Answer

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

Question 17

What is ΔG° at 25°C? 
2O3(g) → 3 O2(g) &emsp; ΔH° = -284 kJ &emsp; ΔS° = 139 J/K

Accepted Answer

A)  -145 kJ 
B)  -243 kJ 
C)  -325 kJ 
D)  -281 kJ 
E)  -287 kJ 
A)  -145 kJ 
B)  -243 kJ 
C)  -325 kJ 
D)  -281 kJ 
E)  -287 kJ

Question 18

If the enthalpy of vaporization of chloromethane, CH3Cl, is 21.5 kJ/mol at the normal boiling point, 249 K, calculate ΔS°vap.

Accepted Answer

A)  86.3 J mol-1 K-1 
B)  5.35 J mol-1 K-1 
C)  11.6 J mol-1 K-1 
D)  896 J mol-1 K-1 
A)  86.3 J mol-1 K-1 
B)  5.35 J mol-1 K-1 
C)  11.6 J mol-1 K-1 
D)  896 J mol-1 K-1

Question 19

Standard Gibbs energy of formation requires the reactants be compounds in their standard state.

Accepted Answer

A) True 
 B)False

Question 20

For a reaction Keq = 1.2 × 10-6 at T = 200 K. What is ΔG° for the reaction?

Accepted Answer

A)  -22.7 kJ/mol 
B)  53.6 kJ/mol 
C)  22.7 kJ/mol 
D)  -53.6 kJ/mol 
E)  170 kJ/mol 
A)  -22.7 kJ/mol 
B)  53.6 kJ/mol 
C)  22.7 kJ/mol 
D)  -53.6 kJ/mol 
E)  170 kJ/mol

Exam 19: Spontaneous Change: Entropy and Free Energy

For the reaction, CaCO3(s) → CaO(s) + CO2(g) S° (J/mol K) 88.70 39.75 213.6 What is ΔS°rxn?

Which of the following has the highest entropy?

Which of the following processes would result in a decrease in system entropy?

If ΔG < 0 for a reaction, then the reaction is said to be:

What is ΔG° at 25 °C? CaCO3(s) → CaO(s) + CO2(g) ΔH° = 177.8 kJ ΔS° = 160.7 J/K

The Gibbs energy change for a reaction is -298 kJ. The reaction is therefore:

The fact that the entropies of vaporization for liquids which exhibit hydrogen bonding are greater than the 87 J/(mol ∙ K) which is expected of non-polar liquids is an exception to:

In a sealed container, the rate of dissolving is equal to the rate of crystallization. Therefore we would expect:

For CdO(s) + SO3(g) → CdSO4(s) ΔH° = -279.4 kJ/mol, and ΔS° = -118.4 J/mol-deg. What is the temperature at which Keq is 1.0 × 104?

Which of the following substances under equal conditions and in the same phase has the greatest molar entropy?

Consider the following reaction: C(g) + 2 H2(g) → CH4(g) S° 5.69 130.58 186.19 J/mol∙deg What is ΔS° for the above reaction in J/mol∙deg?

For the reaction N2O3(g) → NO(g) + NO2(g) ΔG° = -4.78. Calculate Keq at 25°C.

For CO(g) + H2(g) → H2CO(g) ΔH° = -5.36 kJ/mol, and ΔS° = -109.8 J/mol-deg. What is ΔG° in kJ/mol at 300 K?

The normal melting and boiling points of SO2 are 198 and 263 K, respectively. For a plot of the standard molar entropy of SO2 versus temperature, which of the following is INCORRECT?

A reaction is spontaneous if: I. ΔG is a negative value II. both enthalpy and entropy increase III. ΔH is negative and ΔS is positive IV. both enthalpy and entropy decrease V. ΔH is positive and ΔS is negative

What is ΔG° at 25°C? 2O3(g) → 3 O2(g) ΔH° = -284 kJ ΔS° = 139 J/K

If the enthalpy of vaporization of chloromethane, CH3Cl, is 21.5 kJ/mol at the normal boiling point, 249 K, calculate ΔS°vap.

Standard Gibbs energy of formation requires the reactants be compounds in their standard state.

For a reaction Keq = 1.2 × 10-6 at T = 200 K. What is ΔG° for the reaction?

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

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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

For the reaction, CaCO₃(s) → CaO(s) + CO₂(g) S° (J/mol K) 88.70 39.75 213.6 What is ΔS°rxn?

What is ΔG° at 25 °C? CaCO₃(s) → CaO(s) + CO₂(g) ΔH° = 177.8 kJ ΔS° = 160.7 J/K

For CdO(s) + SO₃(g) → CdSO₄(s) ΔH° = -279.4 kJ/mol, and ΔS° = -118.4 J/mol-deg. What is the temperature at which Keq is 1.0 × 10⁴?

Consider the following reaction: C(g) + 2 H₂(g) → CH₄(g) S° 5.69 130.58 186.19 J/mol∙deg What is ΔS° for the above reaction in J/mol∙deg?

For the reaction N₂O₃(g) → NO(g) + NO₂(g) ΔG° = -4.78. Calculate Keq at 25°C.

For CO(g) + H₂(g) → H₂CO(g) ΔH° = -5.36 kJ/mol, and ΔS° = -109.8 J/mol-deg. What is ΔG° in kJ/mol at 300 K?

The normal melting and boiling points of SO₂ are 198 and 263 K, respectively. For a plot of the standard molar entropy of SO₂ versus temperature, which of the following is INCORRECT?

What is ΔG° at 25°C? 2O₃(g) → 3 O₂(g) ΔH° = -284 kJ ΔS° = 139 J/K

If the enthalpy of vaporization of chloromethane, CH₃Cl, is 21.5 kJ/mol at the normal boiling point, 249 K, calculate ΔS°vap.

For a reaction Keq = 1.2 × 10^-6 at T = 200 K. What is ΔG° for the reaction?