Second law of thermodynamics spontaneity and Gibbs free energy - One Line Questions

1. The Helmholtz free energy (A) is defined as: — A = U - TS
2. Which statement best describes the relationship between enthalpy, entropy, and spontaneity at constant T and P? — A decrease in enthalpy and an increase in entropy both favor spontaneity.
3. Which of the following statements correctly defines spontaneity for a process? — A process that occurs without the need for continuous external intervention.
4. In the context of the second law of thermodynamics, the 'universe' is defined as: — The system plus its surroundings.
5. The second law of thermodynamics is often called the law of: — Increasing Entropy
6. The relationship ΔG = ΔH - TΔS is valid for processes occurring at: — Constant temperature and pressure.
7. Which of the following is a consequence of the second law of thermodynamics? — The total entropy of an isolated system never decreases.
8. Which thermodynamic quantity is defined as a measure of the disorder or randomness of a system? — Entropy
9. Which of the following is NOT a state function? — Work
10. Which of the following is a measure of the maximum amount of work that can be extracted from a thermodynamic system at constant temperature and pressure? — Gibbs Free Energy (ΔG)
11. Which of the following processes would have a significant increase in entropy? — Dissolving salt in water
12. For a process occurring at constant volume and temperature, the spontaneity is determined by the change in: — Helmholtz free energy
13. For a reversible reaction at equilibrium, the rate of the forward reaction is: — Equal to the rate of the reverse reaction.
14. If a process is spontaneous, the entropy of the universe must: — Increase
15. Which statement about the Gibbs free energy is correct? — It represents the energy available to do useful work.
16. The Gibbs free energy is a state function. This means: — Its value depends only on the initial and final states.
17. The units of Gibbs free energy are typically: — Kilojoules per mole (kJ/mol)
18. If a reaction has a very large positive equilibrium constant (K >> 1), then the standard Gibbs free energy change (ΔG°) will be: — Large and negative.
19. If ΔG° is negative, the equilibrium constant K will be: — Greater than 1
20. For a process to be spontaneous at constant temperature and pressure, the term TΔS must be: — Greater than ΔH
21. The entropy of a perfectly crystalline solid at absolute zero (0 K) is theoretically: — Zero
22. If ΔG = 0 for a process at constant temperature and pressure, the system is: — At equilibrium
23. For a reversible adiabatic process, the change in entropy of the universe is: — Zero
24. A process that is spontaneous at a given temperature and pressure will have a Gibbs free energy change (ΔG) that is: — Negative
25. When a liquid evaporates, the entropy change (ΔS) is: — Positive
26. The difference between Gibbs free energy (G) and Helmholtz free energy (A) is: — PV
27. The standard Gibbs free energy change (ΔG°) refers to conditions where: — Reactants and products are in their standard states.
28. Consider the reaction N2(g) + 3H2(g) <=> 2NH3(g). If this reaction is exothermic (ΔH < 0) and involves a decrease in the number of moles of gas, how does temperature affect its spontaneity? — Spontaneity decreases with increasing temperature.
29. If ΔH > 0 and ΔS < 0 for a process, it is: — Non-spontaneous at all temperatures.
30. For the reaction A(g) <=> B(g), if ΔH is negative and ΔS is positive, the reaction is: — Spontaneous at all temperatures.
31. Which factor primarily determines the spontaneity of a process at constant temperature and pressure? — The combined effect of enthalpy and entropy changes.
32. What is the term 'TΔS' in the Gibbs free energy equation related to? — The energy that is unavailable to do useful work due to disorder.
33. In the equation ΔG = ΔH - TΔS, the term TΔS represents: — The energy associated with the change in disorder.
34. The spontaneity of a reaction is determined by the sign of ΔG. What does a positive ΔG indicate? — The reaction is spontaneous in the reverse direction.
35. The entropy of a system tends to increase when: — The number of possible microstates increases.
36. The second law of thermodynamics states that for any spontaneous process: — The total entropy of the universe increases.
37. The spontaneity of a process is a kinetic concept. True or False? — False
38. An endothermic process (ΔH > 0) can be spontaneous if: — TΔS is sufficiently large and positive.
39. The entropy change (ΔS) for the expansion of an ideal gas into a vacuum is: — Positive
40. A process is spontaneous at constant volume and temperature if: — ΔA < 0
41. What is the mathematical expression for the change in Gibbs free energy (ΔG) at constant temperature and pressure? — ΔG = ΔH - TΔS
42. The Gibbs free energy change for a reaction at non-standard conditions can be calculated using the equation: — ΔG = ΔG° + RT ln Q
43. A process is spontaneous at constant temperature and pressure if: — ΔG < 0
44. The temperature at which a reversible phase transition occurs (e.g., melting, boiling) is characterized by: — ΔG = 0
45. What is the relationship between the change in Gibbs free energy (ΔG) and the equilibrium constant (K) for a reaction at temperature T? — ΔG° = -RT ln K
46. Consider the melting of ice at 25°C. This process is spontaneous. What can be said about ΔH and ΔS for this process? — ΔH > 0, ΔS > 0
47. An exothermic process (ΔH < 0) is always spontaneous if: — ΔS > 0
48. Consider the dissolution of a solute in a solvent. If ΔH > 0 (endothermic) and the process is spontaneous, then it must be that: — ΔS is positive and large.
49. For an isolated system, a spontaneous process is characterized by: — ΔS_system > 0
50. For a process to be irreversible, the total entropy change of the universe (ΔS_universe) is: — ΔS_universe > 0
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