Define water of crystallisation with two examples. How will you prove their existence in the examples given by you ?

Explanation

Water of crystalliastion 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_2O)`. The water molecules which form part of the structure of a crystal are called water of crystallisation.
(i) Due to loss of water of crystallisation.
`CuSO_4. 5H_2O to^(Heat) CuSO_4+ 5H_2O`
(Hydrated copper sulphate Blue) (Anhydrous copper sulphate white) Water (Goes away)
(ii) BY adding water
`CuSO_4+ 5H_2O to CuSO_4. 5H_2O`
Anhydrous copper sulphate (White) Water Hydrated copper sulphate (Blue)