Copper Sulfate

copper sulfate, common name for the blue crystalline heptahydrate of cupric sulfate, in which copper has valence +2. It may also refer to cuprous sulfate (Cu₂SO₄), in which copper has valence +1.

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copper sulfate [′käp·ər ′səl‚fāt]

(inorganic chemistry)

cupric sulfate

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Copper Sulfate 

(cupric sulfate), CuSO₄; colorless crystals with a density of 3.64 g/cm³. Copper sulfate decomposes upon heating (CuSO₄ = CuO + SO₂ + ½O₂); it is readily soluble in water (23.05 g CuSO₄ per 100 g H₂O at 25°C). The bright blue pentahydrate CuSO₄ · 5H₂O is crystallized from aqueous copper sulfate solutions. Upon heating above 105°C, it converts to CuSO₄- 3H₂O (light blue color); it loses all water at 258°C. The pentahydrate occurs in nature as the mineral chalcanthite, CuSO₄ · 5H₂O.

The pentahydrate is prepared commercially by dissolving copper in heated, dilute sulfuric acid in the presence of blown air, or it can be obtained as a by-product of electrolytic copper refining. It is used in leather tanning, in the manufacture of mineral paints, and in agriculture to destroy plant pests, to control plant diseases, and in seed treatment; it is also used in galvanic cells.