Question

Name the method to prepare sodium which is used for softening hard water and explain how will you prepare it ?

Answer 1

Softening of hard water can be achieved by the addition of washing soda (sodium carbonate). Calcium and magnesium ions present in hard water react with sodium carbonate to produce insoluble carbonates. The soft water now contains soluble and harmless sodium salts.

Sodium bicarbonate is NaHCO₃ while sodium carbonate is Na₂CO₃. Simply heat baking soda or sodium bicarbonate in a 200°F oven for about an hour. Carbon dioxide and water will be given off. Dry sodium carbonate will be obtained as the residue.

2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂