Question

A reaction at 1 bar is non-spontaneous at low temperatures but becomes spontaneous at high temperatures. Identify the correct statement about the reaction among the following.

Options

• ΔH is negative while ΔS is positive.

• Both ΔH and ΔS are negative.

• ΔH is positive while ΔS is negative.

• Both ΔH and ΔS are positive.

Answer 1

Both ΔH and ΔS are positive.

Explanation:

ΔG = ΔH − TΔS

For a spontaneous reaction ΔG = −ve

This is possible when both ΔH and ΔS are positive at high temperatures, so the reaction becomes spontaneous.