The chemical formula of ferrous sulfate FeSO4 is FeSO4·7H2O, commonly known as copperas, which contains seven crystal waters. Light green monoclinic crystal, density 1.898g/cm3, Chemicalbook64℃ melted in crystal water at 64℃. Soluble in water, the aqueous solution is acidic. It is gradually weathered in the air and oxidized to yellow-brown basic iron salt. At 300℃, all the crystal water is lost, and the anhydrous substance is white powder.