Copper(II) sulfate
Molar mass: 159.61 g/mol · Class: Ionic salt
Elements: copper, sulfur, oxygen
Structure
Anhydrous copper(II) sulfate is white; the familiar blue crystals are the pentahydrate, CuSO4·5H2O, with five water molecules bound to each copper ion. Heating drives off the water and turns it white.
Properties
Blue crystals (pentahydrate); white when anhydrous
Very soluble in water, giving blue solutions
Toxic to algae, fungi, and aquatic life
Dehydrates on heating, rehydrating from air
Applications
Fungicide in agriculture (Bordeaux mixture)
Electroplating and copper refining
School chemistry demonstrations
Harmful if swallowed; irritates eyes and skin. Very toxic to aquatic life: never pour solutions down drains or into waterways. Keep locked away from children and pets; wear gloves and goggles when handling.
Data source: IUPAC standard atomic weights 2021; molar mass computed from CuSO4 (anhydrous)