Suggest one method for the removal along with the reactions for

(i) temporary hardness

(ii) permanent hardness of water

(i) Boiling helps to remove the temporary hardness of water. When temporary hard water is boiled, the bicarbonates of calcium and magnesium break up to form their respective insoluble carbonates. These can be filtered out and the water becomes soft.

Ca(HCO₃)₂ $\xrightarrow{\text{boiled}}$ CaCO₃ + H₂O + CO₂ (g)

Mg(HCO₃)₂ $\xrightarrow{\text{boiled}}$ MgCO₃ + H₂O + CO₂ (g)

(ii) The permanent hardness of water is removed when it is treated with a small quantity of sodium carbonate. It reacts with soluble chlorides and sulphates of calcium and magnesium to form respective insoluble carbonates. These are filtered out and water becomes soft.

Na₂CO₃ + CaSO₄ ⟶ CaCO₃ ↓ + Na₂SO₄

Na₂CO₃ + MgCl₂ ⟶ MgCO₃ ↓ + 2NaCl