Enthalpy of solution for copper sulfate

Question

Hi!

I have calculated enthalpy of solution for hydrated copper sulfate and anhydrous copper sulfate, but the value for the hydrated copper sulfate differs from the value from anhydrous copper sulfate. Can someone explain why, please?

Answer 1

The hydrated CuSO₄ has contained in it, the enthalpy of hydration whereas the anhydrous CuSO₄ does not. They both, of course, have the lattice energy which must be overcome for dissolution, but this should be a constant for both salts. So, in summary, one might expect the enthalpy for solution of the hydrated copper sulfate to be higher (and even endothermic) than that for the anhydrous salt (which would probably be exothermic).