Water of crystallisation :
Na2C03 10H2Ois hydrated sodium carbonate salt or sodium carbonate with water of crystallisation. Na2C03 is anhydrous sodium carbonate or salt of sodium carbonate (anhydrous) and 10H2O means water of crystallisation. It impacts on the colour and shape of the crystals.
(i) Used in glass, soap and paper industries.
(ii) Used for removing permanent hardness of water.