Question

Given that the enthalpy of solution of the hydrated copper (II) sulphate is +11.3 kJ/mol, what is the enthalpy of hydration of the anhydrous solid.

• A. 97.321 kJ/mol
• B. 87.321 kJ/mol
• C. 77.971 kJ/mol
• D. None of these

Answer 1

The correct option is C 77.971 kJ/mol

$CuS{O}_4\left(s\right)+5H_{2}O\left(l\right)\to CuS{O}_4\cdot 5H_{2}O\left(s\right)CuS{O}_4\cdot 5H_{2}O\left(s\right)\to CuS{O}_4\left(l\right)+5H_{2}O\left(l\right)\left(1\right)△H_{\circ }=11.3kj/mol\left(given\right)CuS{O}_4\left(s\right)\to CuS{O}_4\left(l\right)q=m△T=50\times 4.18\times 8=1.672kjm=\frac{4}{159.60}=0.02506\left(2\right)△H_{\circ }=\frac{q}{m}=\frac{1.672}{0.02506}=66.71kj/mol\left(2\right)+\left(1\right)CuS{O}_4\cdot 5H_{2}O\to CuS{O}_4+5H_{2}O=66.71+11.3\approx 78kj/mol$