Question

Identify from following the correct set of thermodynamic conditions for the reaction to be spontaneous at all temperature.

• A. $\Delta H>0$ and $\Delta S>0$
• B. $\Delta H<0$ and $\Delta S<0$
• C. $\Delta H<0$ and $\Delta S>0$
• D. $\Delta H>0$ and $\Delta S<0$

Hint:

Negative $\Delta H$ and Positive $\Delta S$ = Always Spontaneous.

Answer 1

The Correct Option is C

Step 1: Concept
Spontaneity is determined by Gibbs Free Energy: $\Delta G = \Delta H - T\Delta S$.

Step 2: Criteria
For a reaction to be spontaneous, $\Delta G$ must be negative ($\Delta G < 0$).

Step 3: Analysis
If $\Delta H$ is negative (exothermic) and $\Delta S$ is positive (entropy increase), the term $-T\Delta S$ will always be negative, making $\Delta G$ negative at all temperatures.

Step 4: Conclusion
Condition (C) ensures spontaneity regardless of T. Final Answer: (C)