Question

The heat of solution of anhydrous CuSO$_4$ and CuSO$_4\cdot$5H$_2$O are $-70$ kJ mol$^{-1}$ and $+12$ kJ mol$^{-1}$ respectively. The heat of hydration of CuSO$_4$ to CuSO$_4\cdot$5H$_2$O is $-x$ kJ. The value of $x$ is _____.

Answer 1

The heat of hydration of CuSO 4 to CuSO 4 · 5H2O is given by the difference between the heat of solution of anhydrous CuSO 4 and CuSO 4 · 5H2O.

Heat of hydration = Heat of solution of anhydrous CuSO 4 − Heat of solution of CuSO 4 · 5H2O.

Substitute the values:

$x = \left| -70 \, \text{kJ mol}^{-1} - \left( +12 \, \text{kJ mol}^{-1} \right) \right|$.

$x = \left| -70 - 12 \right| = \left| -82 \right| = 82$.

Final Answer: 82 kJ.