Question

Dissolution of ammonium chloride in water leads to a cooling sensation. At constant temperature, this process is accompanied by

• A. increase in entropy
• B. decrease in entropy
• C. decrease in enthalpy
• D. no change in entropy

Answer 1

Answer: (A)

increase in entropy

Answer 2

Since, cooling is produced, the reaction is endothermic, ie, $\Delta H=+ ve$.
$\Delta G=\Delta H-T \Delta S$
[For spontaneous process $\Delta G=- ve ]$
As the value of $\Delta H$ is positive, the value of $\Delta S$ must be positive to get a negative value of $\Delta G$. Thus, the process is accompanied by increase in entropy.