Under what conditions is a chemical reaction always thermodynamically spontaneous at all temperatures?
Answer and explanation
Correct answer: B. When Delta H is negative (exothermic) and Delta S is positive (entropy increases)
- Step 1: Gibbs free energy change: Delta G = Delta H - T Delta S. Step 2. If Delta H < 0 and Delta S > 0, then -TDelta S < 0 for all T > 0 K, ensuring Delta G < 0 always. Answer: When Delta H is negative (exothermic) and Delta S is positive (entropy increases). Why not the others: When Delta H > 0 and Delta S < 0, Delta G is positive at all temperatures (never spontaneous).
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