Question

write the name of method for preparation of washing soda in industry and chemical reaction involved in it

Answer 1

1. CO2 reacts with ammonia to form ammonium carbonate.

2NH3 + CO2 + H2O -- (NH4)2CO3

2.Ammonium carbonate further reacts with CO2 to form ammonium bicarbonate.

(NH4)2CO3 + CO2 + H2O -- 2NH4HCO3 (aq.)

3. Ammonium bicarbonate then react with NaCl to form sodium bicarbonate.

NH4HCO3 + NaCl -- NaHCO3 + NH4Cl

Due to exothermic nature of above reactions, solubility of NaHCO3 increases. To counter this effect , the solution is cooled, ppt of NaHCO3 are separated by vacuum filtration and washed to remove ammonium salts.

4.Dry sodium bicarbonate is then heated to give anhydrous sodium carbonate. Carbon dioxide is then again recirculated.

2NaHCO3 -- Na2 CO3 + CO2 + H2 O