Gibbs free-energy change and feasibility Quiz
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5 questions, one answer each
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1. A reaction has ΔH = −40 kJ mol⁻¹ and ΔS = −120 J K⁻¹ mol⁻¹. What is ΔG at 400 K?
- A. −8 kJ mol⁻¹
- B. −88 kJ mol⁻¹
- C. +8 kJ mol⁻¹
- D. +88 kJ mol⁻¹
2. A reaction has negative ΔH and negative ΔS. When is it feasible?
- A. At low temperatures only
- B. At all temperatures
- C. At high temperatures only
- D. At no temperature
3. A reaction has ΔH = +92 kJ mol⁻¹ and ΔS = +230 J K⁻¹ mol⁻¹. Above what temperature is it feasible?
- A. 0.400 K
- B. 2.50 K
- C. 127 K
- D. 400 K
4. Which statement about a reaction with ΔG = −20 kJ mol⁻¹ is correct?
- A. It will always be fast
- B. It is feasible, but may be very slow
- C. It is not feasible
- D. It must be endothermic
5. Which combination of signs makes a reaction feasible at all temperatures?
- A. ΔH positive, ΔS negative
- B. ΔH positive, ΔS positive
- C. ΔH negative, ΔS positive
- D. ΔH negative, ΔS negative