E519 - Copper sulphate

CopperII sulfate, also known as cupric sulfate, or copper sulphate, is the inorganic compound with the chemical formula CuSO4-H2O-x, where x can range from 0 to 5. The pentahydrate -x = 5- is the most common form. Older names for this compound include blue vitriol, bluestone, vitriol of copper, and Roman vitriol.The pentahydrate -CuSO4·5H2O-, the most commonly encountered salt, is bright blue. It exothermically dissolves in water to give the aquo complex [Cu-H2O-6]2+, which has octahedral molecular geometry. The structure of the solid pentahydrate reveals a polymeric structure wherein copper is again octahedral but bound to four water ligands. The Cu-II--H2O-4 centers are interconnected by sulfate anions to form chains. Anhydrous copper sulfate is a white powder. - Wikipedia