- As some salts crystallize from a water solution, they bind water molecules in their crystal
structure. Copper(II) sulfate forms such a hydrate, in which 5 water molecules are present
for every formula unit of copper(II) sulfate. Find the mass percentage of water in copper(II)
sulfate pentahydrate, CuSO, 5H,O, which has a molar mass of 249.68 g/mol.