Question

Explain water of crystallization.

Answer 1

Many salts are found as crystals with water molecules they contain. These water molecules are known as the water of crystallisation. Salts that contain water of crystallisation are called ‘ hydrated salts. The number of molecules of water hydrated to salt is indicated after the dot in its chemical formula. For example, a copper sulphate crystal has five molecules of water for each molecule of copper sulphate. It is written as CuS0₄.5H₂0 and named copper sulphate pentahydrate. This water of crystallisation makes the copper sulphate blue.

When it is heated, it loses its water molecules and becomes white. Salts that do not contain water of crystallisation are called anhydrous salt.