Ch.20 Entropy and Thermodynamics Complete Test Bank

Chapter 20 Test Bank

Thermodynamics: Entropy, Free Energy, and Reaction Direction

1. Which of the following is true for pure oxygen gas, O₂(g) at 25°C?

A. ΔH°_f > 0

B. ΔH°_f < 0

C. ΔG°_f > 0

D. ΔG°_f < 0

E. S° > 0

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

2. A certain process has ΔS_univ > 0 at 25°C. What does one know about the process?

A. It is exothermic.

B. It is endothermic.

C. It is spontaneous at 25°C.

D. It will move rapidly toward equilibrium.

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

3. Which of the following is necessary for a process to be spontaneous?

A. ΔH_sys < 0

B. ΔS_sys > 0

C. ΔS_surr < 0

D. ΔS_univ > 0

E. ΔG_sys = 0

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

4. Which of the following results in a decrease in the entropy of the system?

A. O₂(g), 300 K → O₂(g), 400 K

B. H₂O(s), 0°C → H₂O(l), 0°C

C. N₂(g), 25°C → N₂(aq), 25°C

D. NH₃(l), –34.5°C → NH₃(g), –34.5°C

E. 2H₂O₂(g) → 2H₂O(g) + O₂(g)

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

5. Which of the following should have the greatest molar entropy at 298 K?

A. CH₄(g)

B. H₂O(l)

C. NaCl(s)

D. N₂O₄(g)

E. H₂(g)

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

6. Which of the following is true for a system at equilibrium?

A. ΔS°_sys = ΔS°_surr

B. ΔS°_sys = –ΔS°_surr

C. ΔS°_sys = ΔS°_surr = 0

D. ΔS°_univ > 0

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

7. Which of the following is always true for an exothermic process?

A. q_sys > 0, ΔS_surr < 0

B. q_sys < 0, ΔS_surr > 0

C. q_sys < 0, ΔS_surr < 0

D. q_sys > 0, ΔS_surr > 0

E. w < 0

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

8. Which of the following is always true for an endothermic process?

A. q_sys > 0, ΔS_surr < 0

B. q_sys < 0, ΔS_surr > 0

C. q_sys < 0, ΔS_surr < 0

D. q_sys > 0, ΔS_surr > 0

E. w < 0

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

9. Which of the following values is based on the Third Law of Thermodynamics?

A. ΔH°_f = 0 for Al(s) at 298 K

B. ΔG°_f = 0 for H₂(g) at 298 K

C. S° = 51.446 J/(mol·K) for Na(s) at 298 K

D. q_sys < 0 for H₂O(l) → H₂O(s) at 0°C

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Third Law of Thermodynamics (Entropy and Absolute Zero)

Topic: Thermodynamics (Entropy and Free Energy)

10. When a sky diver free-falls through the air, the process is

A. non-spontaneous because he is accelerating due to the force applied by gravity.

B. non-spontaneous because he is losing potential energy.

C. non-spontaneous, if he had planned the jump for two weeks.

D. spontaneous.

E. in equilibrium.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

11. Which, if any, of the following processes is spontaneous under the specified conditions?

A. H₂O(l) → H₂O(s) at 25°C

B. CO₂(s) → CO₂(g) at 0°C

C. 2H₂O(g) → 2H₂(g) + O₂(g)

D. C(graphite) → C(diamond) at 25°C and 1 atm pressure

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

12. Which relationship or statement best describes ΔS° for the following reaction?

Pb(s) + Cl₂(g) → PbCl₂(s)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

13. Which relationship or statement best describes ΔS° for the following reaction?

HgS(s) + O₂(g) → Hg(l) + SO₂(g)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

14. Which relationship or statement best describes ΔS° for the following reaction?

2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

15. Which relationship best describes ΔS° for the following reaction?

CO(g) + H₂O(g) → CO₂(g) + H₂(g)

A. ΔS° = ΔH°

B. ΔS° = ΔH°/T

C. ΔS° > 0

D. ΔS° < 0

E. ΔS° ≈ 0

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

16. Which relationship or statement best describes ΔS° for the following reaction?

2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

17. Which relationship best describes ΔS° for the following reaction?

8H₂(g) + S₈(s) → 8H₂S(g)

A. ΔS° = ΔH°

B. ΔS° = ΔH°/T

C. ΔS° ≈ 0

D. ΔS° < 0

E. ΔS° > 0

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

18. Which relationship or statement best describes ΔS° for the following reaction?

O₃(g) + NO(g) → O₂(g) + NO₂(g)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

19. Which relationship or statement best describes ΔS° for the following reaction?

C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

20. Which relationship or statement best describes ΔS° for the following reaction?

KCl(s) → K⁺(aq) + Cl^–(aq)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

21. Which relationship or statement best describes ΔS° for the following reaction?

BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = H°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

22. Which relationship or statement best describes ΔS° for the following reaction?

CaO(s) + CO₂(g) → CaCO₃(s)

A. ΔS° ≈ 0

B. ΔS° < 0

C. ΔS° > 0

D. ΔS° = ΔH°/T

E. More information is needed to make a reasonable prediction.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

23. Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

A. CO(g), CO₂(g)

B. NaCl(s), NaCl(aq)

C. H₂S(g), H₂S(aq)

D. Li(s), Pb(s)

E. H₂(g), H₂O(g)

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

24. You are given pure samples of ethane, C₂H₆(g), and toluene, C₇H₈(l). What prediction would you make concerning their standard molar entropies at 298 K?

A. S°_ethane > S°_toluene

B. S°_ethane < S°_toluene

C. S°_ethane ≈ (S°_toluene) ÷ 3

D. S°_ethane ≈ S°_toluene

E. Since toluene is much more complex than ethane, but ethane is in the gas phase while toluene is a liquid, any of these predictions can be confidently made without further information or calculations.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Hard

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

25. You are given pure samples of pentane, CH₃CH₂CH₂CH₂CH₃(l), and 1,3-pentadiene, CH₂=CHCH=CHCH₃(l). What prediction would you make concerning their standard molar entropies at 298 K?

A. S°_pentane > S°1, 3-_pentadiene

B. S°_pentane < S°1, 3-_pentadiene

C. S°_pentane ≈ S°1, 3-_pentadiene

D. S°_pentane = S°1, 3-_pentadiene + 2 S°_H2

E. More information is needed to make reasonable predictions.

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

26. You are given pure samples of ammonia, NH₃(g), and nitrogen trifluoride, NF₃(g). What prediction would you make concerning their standard molar entropies at 298 K?

A. S°_ammonia > S°_{nitrogen trifluoride}

B. S°_ammonia < S°_{nitrogen trifluoride}

C. S°_ammonia ≈ S°_{nitrogen trifluoride}

D. Other conditions need to be specified before a reliable prediction can be made.

E. Even if more conditions are specified, a reliable prediction cannot be made.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

27. In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

A. 1 mole He(g); 1 mole Kr(g)

B. 1 mole O₂(g); 2 mole O(g)

C. 1 mole CH₄(g); 1 mole C₂H₆(g)

D. 1 mole Xe(g) at 1 atmosphere; 1 mole Xe(g) at 0.5 atmosphere

E. 20 one-dollar bills distributed randomly among 20 people; 20 one-dollar bills distributed randomly among 10 people

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

28. In which one of these pairs will the entropy of the first substance be greater than that of the second? Assume P and T are the same for each pair, unless stated otherwise.

A. 1 mole of F₂(g); 1 mole of Cl₂(g)

B. 1 mole of I₂(s); 1 mole of I₂(g)

C. 1 mole of CaCO₃(s); 1 mole of CaO(s) plus 1 mole of CO₂(g)

D. 1 mole of H₂(g) at 25°C; 1 mole of H₂(g) at 50°C

E. 1 mole of O₃(g); 1 mole of O₂(g)

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

29. Which one of the following phase changes decreases the entropy of the system?

A. Melting

B. Heating a gas

C. Vaporization

D. Condensation

E. Sublimation

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

30. Which one of the following changes of state increases the entropy of the system?

A. Condensation

B. Cooling a gas

C. Freezing

D. Crystallization

E. Sublimation

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

31. A sample of water is heated at a constant pressure of one atmosphere. Initially, the sample is ice at 260 K, and at the end the sample consists of steam at 400 K. In which of the following 5K temperature intervals would there be the greatest increase in the entropy of the sample?

A. from 260 K to 265 K

B. from 275 K to 280 K

C. from 360 K to 365 K

D. 370 K to 375 K

E. from 395 K to 400 K

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

32. Calculate ΔS° for the reaction

SiCl₄(g) + 2Mg(s) → 2MgCl₂(s) + Si(s)

Substance: SiCl4(g) Mg(s) MgCl₂(s) Si(s)

S°(J/K·mol): 330.73 32.68 89.62 18.83

A. –254.96 J/K

B. –198.02 J/K

C. 198.02 J/K

D. 254.96 J/K

E. 471.86 J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

33. Calculate ΔS° for the reaction

4Cr(s) + 3O₂(g) → 2Cr₂O₃(s)

Substance: Cr(s) O₂(g) Cr₂O₃(s)

S°(J/K·mol): 23.77 205.138 81.2

A. –548.1 J/K

B. –147.7 J/K

C. 147.7 J/K

D. 310.1 J/K

E. 548.1 J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

34. Calculate ΔS° for the reaction

2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

Substance: Cl₂(g) SO₂(g) SOCl₂(g) Cl₂O(g)

S°(J/K·mol): 223.0 248.1 309.77 266.1

A. –118.2 J/K

B. –104.8 J/K

C. 104.8 J/K

D. 118.2 J/K

E. 1270.0 J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

35. Calculate ΔS° for the combustion of propane.

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g)

Substance: C₃H₈(g) O₂(g) CO₂(g) H₂O(g)

S°(J/K·mol): 269.9 205.138 213.74 18.825

A. –100.9 J/K

B. –72.5 J/K

C. 72.5 J/K

D. 100.9 J/K

E. 877.5 J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

36. Elemental boron can be formed by reaction of boron trichloride with hydrogen.

BCl₃(g) + 1.5H₂(g) → B(s) + 3HCl(g)

Substance: BCl₃(g) H₂(g) B(s) HCl(g)

S°(J/K·mol): ? 130.6 5.87 186.8

If ΔS° = 80.3 J/K for the reaction above, what is S° for BCl₃(g)?

A. –18.2 J/K·mol

B. 18.2 J/K·mol

C. 290.1 J/K·mol

D. 355.4 J/K.mol

E. 450.6 J/K·mol

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

37. For a chemical reaction to be spontaneous only at high temperatures, which of the following conditions must be met?

A. ΔS° > 0, ΔH° > 0

B. ΔS° > 0, ΔH° < 0

C. ΔS° < 0, ΔH° < 0

D. ΔS° < 0, ΔH° > 0

E. ΔG° > 0

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

38. For a chemical reaction to be spontaneous only at low temperatures, which of the following conditions must be met?

A. ΔS° > 0, ΔH° > 0

B. ΔS° > 0, ΔH° < 0

C. ΔS° < 0, ΔH° < 0

D. ΔS° < 0, ΔH° > 0

E. ΔG° > 0

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

39. For a chemical reaction to be spontaneous at all temperatures, which of the following conditions must be met?

A. ΔS° > 0, ΔH° > 0

B. ΔS° > 0, ΔH° < 0

C. ΔS° < 0, ΔH° < 0

D. ΔS° < 0, ΔH° > 0

E. It is not possible for a reaction to be spontaneous at all temperatures.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

40. For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

A. ΔS° > 0, ΔH° > 0

B. ΔS° > 0, ΔH° < 0

C. ΔS° < 0, ΔH° < 0

D. ΔS° < 0, ΔH° > 0

E. All reactions are spontaneous at some temperature.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

41. For a process with ΔS < 0, which one of the following statements is correct?

A. The process will definitely be spontaneous if ΔH < 0.

B. The process will be definitely be spontaneous if ΔH < TΔS.

C. The process can never be spontaneous.

D. The process will definitely be spontaneous, regardless of ΔH.

E. The process will definitely be spontaneous if ΔS_surr > 0.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

42. Consider the following quantities used in thermodynamics: E, H, q, w, S, G. How many of them are state functions?

A. 0

B. 1

C. 2

D. 3

E. 4

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

43. In order for a process to be spontaneous,

A. ΔH must be less than zero.

B. ΔS must be greater than zero.

C. ΔG must be greater than zero.

D. it should be rapid.

E. ΔS_sys + ΔS_surr must be greater than zero.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

44. Which of the following conditions will ensure that a chemical reaction will definitely proceed in the forward direction, toward products?

A. ΔH > 0

B. ΔH < 0

C. ΔS_sys > 0

D. ΔS_surr > ΔS_sys

E. ΔS > ΔH/T

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Spontaneous Change

Topic: Thermodynamics (Entropy and Free Energy)

45. Given: H₂O(l) → H₂O(g) ΔH° = 40.7 kJ at 373K

What is the entropy change in the system (ΔS) when one mole of water vaporizes at 100°C and a pressure of one atmosphere?

A. 407 J/K

B. –407 J/K

C. 109 J/K

D. –109 J/K

E. J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

46. Given: H₂O(l) → H₂O(s) ΔH° = –6.02 kJ at 273K

Calculate the entropy change of the surroundings (ΔS_surr) when one mole of water freezes at 0°C and a pressure of one atmosphere.

A. 22.1 J/K

B. –22.1 J/K

C. 397 J/K

D. –397 J/K

E. 0.022 J/K

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

47. A certain process has ΔH° > 0, ΔS° < 0, and ΔG° > 0. The values of ΔH° and ΔS° do not depend on the temperature. Which of the following is a correct conclusion about this process?

A. It is non-spontaneous at all T.

B. It is spontaneous at high T.

C. It is spontaneous at low T.

D. It is spontaneous at all T.

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

48. The second law of thermodynamics tells us that

A. the entropy of the universe is constant.

B. entropy is neither created nor destroyed.

C. the universe proceeds toward a state of lower entropy.

D. the universe proceeds toward a state of higher entropy.

E. the universe cannot create entropy.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

49. In order for a process to be spontaneous,

A. the entropy of the system must increase.

B. the entropy of the surroundings must increase.

C. the entropy of the universe must decrease.

D. the entropy of the surroundings must decrease.

E. the entropy change of the surroundings plus the entropy change of the system must be positive.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

50. Calculate ΔG° for the reaction

SiCl₄(g) + 2Mg(s) → 2MgCl₂(s) + Si(s)

Substance: SiCl₄(g) Mg(s) MgCl₂(s) Si(s)

ΔG°_f (kJ/mol): –616.98 0 –591.79 0

A. 566.60 kJ

B. 50.38 kJ

C. 25.19 kJ

D. –25.19 kJ

E. –566.60 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

51. Calculate ΔG° for the combustion of propane.

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g)

Substance: C₃H₈(g) O₂(g) CO₂(g) H₂O(g)

ΔG°_f (kJ/mol): –24.5 0 –394.4 –228.6

A. –2073.1 kJ

B. –1387.3 kJ

C. –598.5 kJ

D. 598.5 kJ

E. 2073.1 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

52. Elemental boron can be formed by reaction of boron trichloride with hydrogen.

BCl₃(g) + 1.5H₂(g) → B(s) + 3HCl(g)

Calculate ΔG° for the reaction.

Substance: BCl₃(g) H₂(g) B(s) HCl(g)

ΔG°_f (kJ/mol): –388.7 0 0 –95.3

A. –293.4 kJ

B. 293.4 kJ

C. –102.8 kJ

D. 102.8 kJ

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

53. Calculate ΔG° for the reaction of ammonia with fluorine.

2NH₃(g) + 5F₂(g) → N₂F₄(g) + 6HF(g)

Substance: NH₃(g) F₂(g) N₂F₄(g) HF(g)

ΔG°_f (kJ/mol): –16.4 0 9.9 –275.4

A. 179.1 kJ

B. –179.1 kJ

C. 1539.7 kJ

D. –1539.7 kJ

E. None of these choices are correct.

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

54. Use the given data at 298 K to calculate ΔG° for the reaction

2Cl₂(g) + SO₂(g) → SOCl₂(g) + Cl₂O(g)

Substance: Cl₂(g) SO₂(g) SOCl₂ (g) Cl₂O(g)

ΔH°_f (kJ/mol): 0 –296.8 –212.5 80.3

S°(J/K·mol): 223.0 248.1 309.77 266.1

A. 129.3 kJ

B. 133.6 kJ

C. 196.0 kJ

D. 199.8 kJ

E. 229.6 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Hard

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

55. “A diamond is forever” is one of the most successful advertising slogans of all time. But is it true? For the reaction shown below, calculate the standard free energy change at 298K and determine whether or not a diamond is “forever”. C(diamond) → C(graphite)

Data: ΔH_f°(diamond) = 1.895 kJ/mol; S°(diamond) = 2.337 J mol^–1K^–1; S°(graphite) = 5.740 J mol^–1K^–1.

A. ΔG° = 2.19 kJ; forever

B. ΔG° = –1.90 kJ; not forever

C. ΔG° = –2.90 kJ; not forever

D. ΔG° = 1.90 kJ; forever

E. ΔG° = < –1000 kJ; not forever

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

56. Hydrogen sulfide decomposes according to the following reaction

2H₂S(g) → 2H₂(g) + S₂(g)

For this reaction at 298K ΔS° = 78.1 J/K, ΔH° = 169.4 kJ, and ΔG° = 146.1 kJ. What is the value of ΔG° at 900 K?

A. –69881 kJ

B. 48.4 kJ

C. 99.1 kJ

D. 240 kJ

E. 441 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

57. Nitric oxide reacts with chlorine to form NOCl. The data refer to 298 K.

2NO(g) + Cl₂(g) → 2NOCl(g)

Substance: NO(g) Cl₂(g) NOCl(g)

ΔH°_f (kJ/mol): 90.29 0 51.71

ΔG°_f (kJ/mol): 86.60 0 66.07

S°(J/K·mol): 210.65 223.0 261.6

What is the value of ΔG° for this reaction at 550 K?

A. –143.76 kJ

B. –78.78 kJ

C. –22.24 kJ

D. –10.56 kJ

E. 66600 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

58. Sulfuryl dichloride is formed when sulfur dioxide reacts with chlorine. The data refer to 298 K.

SO₂(g) + Cl₂(g) → SO₂Cl₂(g)

Substance: SO₂(g) Cl₂(g) SO₂Cl₂(g)

ΔH°_f (kJ/mol): –296.8 0 –364.0

ΔG°_f (kJ/mol): –300.1 0 –320.0

S°(J/K·mol): 248.2 223.0 311.9

What is the value of ΔG° for this reaction at 600 K?

A. –162.8 kJ

B. –40.1 kJ

C. –28.4 kJ

D. 28.4 kJ

E. 162.8 kJ

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

59. The temperature at which the following process reaches equilibrium at 1.0 atm is the normal boiling point of hydrogen peroxide.

H₂O₂(l) H₂O₂(g)

Use the following thermodynamic information at 298 K to determine this temperature.

Substance: H₂O₂(l) H₂O₂(g)

ΔH°_f (kJ/mol): –187.7 –136.3

ΔG°_f (kJ/mol): –120.4 –105.6

S°(J/K·mol): 109.6 232.7

A. 120°C

B. 144°C

C. 196°C

D. 418°C

E. 585°C

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

60. The temperature at which the following process reaches equilibrium at 1.0 atm is the normal melting point for phosphoric acid.

H₃PO₄(s) H₃PO₄(l)

Use the following thermodynamic information at 298 K to determine this temperature.

Substance: H₃PO₄(s) H₃PO₄(l)

ΔH°f (kJ/mol): –1284.4 –1271.7

ΔG°f (kJ/mol): –1124.3 –105.6

S°(J/K·mol): 110.5 150.8

A. 286 K

B. 305 K

C. 315 K

D. 347 K

E. 3170 K

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

61. Consider the figure that shows ΔG° for a chemical process plotted against absolute temperature.

Which one of the following is an incorrect conclusion, based on the information in the diagram?

A. ΔH° > 0

B. ΔS° > 0

C. The reaction is spontaneous at high temperatures.

D. ΔS° increases with temperature while ΔH° remains constant.

E. There exists a certain temperature at which ΔH° = TΔS°.

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

62. Consider the figure that shows ΔG° for a chemical process plotted against absolute temperature.

From this plot, it is reasonable to conclude that

A. ΔH° > 0, ΔS° > 0

B. ΔH° > 0, ΔS° < 0

C. ΔH° < 0, ΔS° > 0

D. ΔH° < 0, ΔS° < 0

E. None of these choices are correct.

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

63. Consider the figure that shows ΔG° for a chemical process plotted against absolute temperature.

From this plot, it is reasonable to conclude that

A. ΔH° > 0, ΔS° > 0

B. ΔH° > 0, ΔS° < 0

C. ΔH° < 0, ΔS° > 0

D. ΔH° < 0, ΔS° < 0

E. None of these choices are correct.

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

64. A reaction is proceeding toward equilibrium. At a certain stage, the concentrations of reactants and products are such that ΔG = ΔG°. What conclusion can reasonably be drawn about the reaction at this time?

A. K > Q

B. K < Q

C. K = Q

D. K = 1

E. Q = 1

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Hard

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

65. Iron(III) oxide can be reduced by carbon monoxide.

Fe₂O₃(s) + 3CO(g)2Fe(s) + 3CO₂(g)

Use the following thermodynamic data at 298 K to determine the equilibrium constant at this temperature.

Substance: Fe₂O₃(s) CO(g) Fe(s) CO₂(g)

ΔH°_f (kJ/mol): –824.2 –110.5 0 –393.5

ΔG°_f (kJ/mol): –742.2 –137.2 0 –394.4

S°(J/K·mol): 87.4 197.7 27.78 213.7

A. 7.0 × 10^–6

B. 1.3 × 10^–3

C. 2.2 × 10⁴

D. 1.4 × 10⁵

E. > 2.0 × 10⁵

Bloom's: 3. Apply

Difficulty: Hard

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

66. Calculate the equilibrium constant at 25°C for the reaction of methane with water to form carbon dioxide and hydrogen. The data refer to 25°C.

CH₄(g) + 2H₂O(g)CO₂(g) + 4H₂(g)

Substance: CH₄(g) H₂O(g) CO₂(g) H₂(g)

ΔH°_f (kJ/mol): –74.87 –241.8 –393.5 0

ΔG°_f (kJ/mol): –50.81 –228.6 –394.4 0

S°(J/K·mol): 186.1 188.8 213.7 130.7

A. 8.2 × 10¹⁹

B. 0.96

C. 0.58

D. 1.2 × 10^–20

E. 1.4 × 10^–46

Bloom's: 3. Apply

Difficulty: Hard

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

67. The reaction of methane with water to form carbon dioxide and hydrogen is nonspontaneous at 298 K. At what temperature will this system make the transition from nonspontaneous to spontaneous? The data refer to 298 K.

CH₄(g) + 2H₂O(g) CO₂(g) + 4H₂(g)

Substance: CH₄(g) H₂O(g) CO₂(g) H₂(g)

ΔH°f (kJ/mol): –74.87 –241.8 –393.5 0

ΔG°f (kJ/mol): –50.81 –228.6 –394.4 0

S°(J/K·mol): 186.1 188.8 213.7 130.7

A. 658 K

B. 683 K

C. 955 K

D. 1047 K

E. 1229 K

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

68. Use the thermodynamic data at 298 K below to determine the K_sp for barium carbonate, BaCO₃ at this temperature.

Substance: Ba²⁺(aq) CO₃^2–(aq) BaCO₃(s)

ΔH°f (kJ/mol): –538.36 –676.26 –1219

ΔG°f (kJ/mol): –560.7 –528.1 –1139

S°(J/K·mol): 13 –53.1 112

A. 5.86

B. 6.30 × 10⁸

C. 1.59 × 10^–9

D. 5.47 × 10^–21

E. 2.18 × 10^–27

Accessibility: Keyboard Navigation

Bloom's: 3. Apply

Difficulty: Hard

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

69. What is the free energy change, ΔG°, for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453°C? K_c = 0.020

2HI(g) H₂(g) + I₂(g)

A. 6.4 kJ

B. 8.8 kJ

C. 15 kJ

D. 19 kJ

E. 24 kJ

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

70. The formation constant for the reaction

Ag⁺(aq) + 2NH₃(aq) Ag(NH₃)²⁺(aq)

is K_f = 1.7 × 10⁷ at 25°C. What is ΔG° at this temperature?

A. –1.5 kJ

B. –3.5 kJ

C. –18 kJ

D. –23 kJ

E. –41 kJ

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

71. Consider the reaction

CuI(s) Cu⁺(aq) + I^–(aq)

If the concentrations of the Cu⁺ and I^– ions in equilibrium at 298 K are both equal to 1.03 × 10^–6 M, what is the value of ΔG° for the reaction?

A. –68 kJ

B. 68 kJ

C. –30. kJ

D. 30 kJ

E. 34 kJ

Bloom's: 3. Apply

Difficulty: Hard

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

72. A reaction has ΔG = 10.0 kJ and ΔG° = 15.0 kJ at a temperature of 50°C. Calculate the value of the reaction quotient Q under these conditions.

A. 0.16

B. 9.1 × 10^–5

C. 1.1 × 10⁴

D. 6.4

E. 6.0 × 10^–6

Bloom's: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

73. Under a given set of conditions, all microstates of a system are equally probable.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

74. The term microstate refers to the energy state of a single molecule in a system of many molecules.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

75. The higher the pressure of a gas sample, the greater is its entropy.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

76. The entropy of one mole of oxygen gas in a 0.5-L container is less than it would be in a 22.4-L container at the same temperature.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

77. In a spontaneous process, the entropy of the system always increases.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

78. In some spontaneous processes, the entropy of the surroundings decreases.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

79. For a reaction at equilibrium, ΔS_univ = 0.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Entropy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

80. The free energy of a perfect crystal at absolute zero, is zero.

Accessibility: Keyboard Navigation

Bloom's: 1. Remember

Difficulty: Medium

Gradable: automatic

Subtopic: Third Law of Thermodynamics (Entropy and Absolute Zero)

Topic: Thermodynamics (Entropy and Free Energy)

81. For a given reaction, a change in the pressure may result in a change in the sign of ΔG.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Gibbs Free Energy (Definition and Calculation)

Topic: Thermodynamics (Entropy and Free Energy)

82. For any reaction, if ΔG° > 0, then K < 1.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

83. As a chemical reaction proceeds toward equilibrium, the free energy of the system decreases.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Free Energy and Equilibrium

Topic: Thermodynamics (Entropy and Free Energy)

84. In 1774 Joseph Priestley prepared the element oxygen by heating mercury(II) oxide:

HgO(s) → Hg(l) + ½O2(g)

For this reaction, ΔH° = 90.84 kJ and ΔS° = 108 J/K. Which of the following statements is true?

A. The reaction is only spontaneous at low temperatures.

B. The reaction is spontaneous at all temperatures.

C. ΔG° becomes less favorable as the temperature is raised.

D. The reaction is spontaneous only at high temperatures.

E. The reaction is spontaneous under standard conditions at 25°C.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

85. Select the correct statement of a law of thermodynamics.

A. The enthalpy of the universe is constantly increasing.

B. The entropy of the universe is constant.

C. The entropy of an element in its standard state at 25°C is zero.

D. Every spontaneous process is accompanied by an increase in total entropy.

E. Every spontaneous process is accompanied by a decrease in the enthalpy of the system.

Accessibility: Keyboard Navigation

Bloom's: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity)

Topic: Thermodynamics (Entropy and Free Energy)

Category # of Questions

Accessibility: Keyboard Navigation 72

Bloom's: 1. Remember 14

Bloom's: 2. Understand 45

Bloom's: 3. Apply 26

Difficulty: Easy 23

Difficulty: Hard 7

Difficulty: Medium 55

Gradable: automatic 85

Subtopic: Entropy (Definition and Calculation) 38

Subtopic: Free Energy and Equilibrium 9

Subtopic: Gibbs Free Energy (Definition and Calculation) 23

Subtopic: Second Law of Thermodynamics (Entropy and Spontaneity) 6

Subtopic: Spontaneous Change 7

Subtopic: Third Law of Thermodynamics (Entropy and Absolute Zero) 2

Topic: Thermodynamics (Entropy and Free Energy) 85