Copper(II) sulfate decahydrate, often referred to as blue vitriol, is a bright blue crystalline compound with the chemical formula CuSO4·10H2O. It consists of one copper ion, one sulfate ion, and ten water molecules. This compound is commonly used in agriculture as a fungicide and herbicide, as well as in various industrial applications. When heated, copper(II) sulfate decahydrate loses its water molecules, transforming into anhydrous copper(II) sulfate, which is a white powder. The compound is soluble in water, making it useful in laboratory experiments and chemical reactions. Its distinctive color and properties make it a popular choice for educational demonstrations in chemistry.