Copper Sulphate (CuSO4.5H2O); Blue vitriol
In laboratory it is prepared by dissolving cupric oxide (or) cupric hydroxide (or) cupric carbonate in dilute H2SO4
CuO + H2SO4 ® CuSO4 + H2O
Cu(OH)2 + H2SO4 ® CuSO4 + 2H2O
CuCO3 + H2SO4 ® CuSO4 + H2O + CO2
1. The anhydrous salt is colourless but the hydrated salt is blue in colour.
2. It readily dissolves in water but is insoluble in alcohol.
1. Action of Heat
On heating CuSO4.5H2O loses its water of crystallization and decomposes at 720 o C to give cupric oxide and sulphur trioxide.
2. Action of ammonia
Copper sulphate gives deep blue colour with NH4OH forming complex compound.
CuSO4 + 4NH4OH ® [Cu (NH3)4]SO4 + 4H2O
3. Action of KI
When KI is added to a solution of CuSO4, a white precipitate of cuprous iodide is produced.
CuSO4 + 2KI ® Cu I2 + K2SO4
2CuI2 ® Cu2I2 + I2
4. Action with KCN
A yellow precipitate of cupric cyanide is first formed with KCN and it decomposes to give cyanogen gas.
CuSO4 + 2KCN ® Cu(CN)2 + K2SO4
2Cu(CN)2 ® Cu2(CN)2 + (CN)2
5. Action of alkalies
With alkalies, a pale blue precipitate of copper hydroxide is formed.
CuSO4 + 2NaOH ® Cu(OH)2 + Na2SO4
Pale blue precipitate
6. Action with H2S
With H2S it gives a black precipitate of copper sulphide.
CuSO4 + H2S ® CuS + H2SO4 (Black ppt)
1. It is used as a germicide and insecticide in agriculture.
2. A mixture of copper sulphate and lime, commonly known as Bordeaux
mixture, is used as fungicide.
3. It is used in electroplating, calicoprinting and in electrical batteries.