Question

Which of the following reactions is said to be entropy driven?

• A. Endothermic reaction with positive entropy change at high temperature
• B. Endothermic reaction with negative entropy change at low temperature
• C. Exothermic reaction with positive entropy change at high temperature
• D. Exothermic reaction with negative entropy change at low temperature

Answer 1

Answer: (A)

For endothermic reaction, $\Delta H=+ ve .$ For reaction to be spontaneous, $\Delta S$ must be positive and also $T \Delta S$ must be greater than $\Delta H$ in magnitude. The reaction is then said to be entropy driven.