Question

A chemical reaction with a negative enthalpy change and a negative entropy change ________. A) Must be nonspontaneous Is not possible B) Could be either spontaneous or nonspontaneous depending on the temperature C) Must be spontaneous

Answer 1

Answer:

Could be either spontaneous or nonspontaneous depending on the temperature

Explanation:

For a reaction to be spontaneous, Gibbs free energy must be negative.

The relation between enthalpy, entropy and temperature is as follows:

$\Delta G=\Delta H-T\Delta S$

ΔG is change Gibbs free energy, ΔH is change in enthalpy, ΔS is change in entropy and T is temperature.

In the given condition, ΔH is negative and ΔS is negative. As ΔS is also negative then ΔG cannot be negative at all temperature (Particulary at high temperature) and thus, reaction could be nonspontaneous.

Therefore, in the given the reaction, could be either spontaneous or nonspontaneous depending on the temperature.