Question

Why is anhydrous copper sulfate a white powder, while `CuSO_4*5H_2O` a blue crystal?

Answer 1

Because the waters of hydration are incorporated into the crystal structure of the solvate.

Explanation:

`"Copper sulfate pentahydrate"`, `CuSO_4*5H_2O`, gives beautiful macroscopic crystals.....

The water molecules are actually incorporated into the coordination sphere of the copper ion. Dry the crystals thoroughly (no easy task), and you are left with anhydrous `CuSO_4`, a white salt.