Science Fair Project Encyclopedia
Copper(II) sulfate
Copper(II) sulfate (CuSO4) is the most common copper salt, made by the action of sulfuric acid on the base copper(II) oxide. The anhydrous form is a pale green or gray-white powder, while the hydrated form is bright blue. The archaic name for copper(II) sulfate was cupric sulfate. Some common names are: blue stone and blue vitriol.
Copper(II) sulfate is a desiccant. As such, it most commonly occurs in nature as copper(II) sulfate pentahydrate (CuSO4 · 5H2O). This mineral is called chalcanthite. Copper(II) sulfate decomposes before melting. The common pentahydrate form dehydrates, losing four water molecules at 110 °C and all five at 150 °C. At 650 °C copper(II) sulfate decomposes into copper(II) oxide (CuO), Sulfur dioxide (SO2) and oxygen (O2).
It can be used to plate metals with copper, as a fungicide or herbicide, or as a chemical test for water (the anhydrous form will absorb water, turning blue).
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