Question

A spontaneous reaction is impossible if:

• A. both \(\Delta H\) and \(\Delta S\) are negative
• B. both \(\Delta H\) and \(\Delta S\) are positive
• C. \(\Delta H\) is negative and \(\Delta S\) is positive
• D. \(\Delta H\) is positive and \(\Delta S\) is negative

Hint:

\(\Delta H > 0\) and \(\Delta S < 0\) ⇒ non-spontaneous always.

Answer 1

The Correct Option is D

Step 1: Gibbs free energy: \[ \Delta G = \Delta H - T\Delta S \]
Step 2: If \(\Delta H > 0\) and \(\Delta S < 0\), then \(\Delta G > 0\) at all temperatures.