Copper (ii) sulfate, also known as cupric sulfate or copper sulphate, is the inorganic compound with the chemical formula cuso4. This salt exists as a series of compounds that differ in their degree of hydration. The anhydrous salt is a white powder in its pure form, whereas the pentahydrate (cuso4â·5h2o), the most commonly encountered salt, is bright blue. Copper (ii) sulfate exothermically dissolves in water to give the aquo complex [cu(h2o)6]2+, which has octahedral molecular geometry and is paramagnetic. Other names for copper(ii) sulfate are "blue vitriol" and "bluestone"