Question

The heat solution of anhydrous $Cu{SO}_4$ is $-15.9kcal$ and that of $Cu{SO}_4.5H_{2}O$ is $2.8kcal$. Calculate the heat of hydration of $Cu{SO}_4$.

• A. $-18.7kcal$
• B. $+18.7kcal$
• C. $-13.1kcal$
• D. None of these

Answer 1

The correct option is A $-18.7kcal$

Applying Hess's law (See image in the hint)

$\Delta H+2.8=-15.9$
$\Delta H=-15.9-2.8=-18.7kcal$

Hence option A is correct