What is meant by water of crystallisation ? Explain that the crystalline salts contain water of crystallisation.

Explanation

Water of crystallisation is a fixed number of water molecules present in one formula unit of a salt . One formula unit of copper sulphate contains five water molecules `(5H_(2)O)`. The water molecules which form part of the structure of a crystal are called water of crystallisation. When hydrated salts are heated strong heating , blue copper sulphate crystals turn white (due to the loass of water of crystallisation)
`underset(("Blue"))underset("copper sulphate")underset("Hydrated")(CuSO_(4).5H_(2)O)overset("heat")rarrunderset("White")underset("copper sulphate")underset("Anhydrous")(CuSO_4)+underset("Goes away")underset("Water")(5H_2O)`
Anhydrous copper sulphate turns blue on adding water.
`underset(("White"))underset("copper sulphate")underset("Anhydrous")(CuSO_4)+underset("Water")(5H_2O)rarrunderset("(Blue)")underset("copper sulphate")underset("Hydrated")(CuSO_(4).5H_(2)O)`