Permanent hardness of water can be removed by adding (AFMC 2010)

Permanent hardness is due to the presence of chlorides and sulphates salts of calcium and magnesium. And permanent hardness can be removed by adding sodium carbonate. 2 ( ) 2 3( ) 3( ) ( ) 2 aq aq s aq Ca Na CO CaCO Na -> 2 ( ) 2 3( ) 3( ) ( ) 2 aq aq s aq Mg Na CO MgCO Na ->