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

Answer 1

Answer: (D)

$\Delta H$ is positive and $\Delta S$ is negative

Answer 2

$\Delta G = \Delta H - T \Delta S$
If $\Delta H$ is positive and $\Delta S$ is negative, then $\Delta G$ will be positive, hence a spontaneous reaction is impossible