Describe solvay process (or) how is washing soda ( or) sodium carbonate prepared in industries?

Explanation

(i) Solvay process - in this process ammonia is converted to ammonium carbonate which is then converted to ammonium bicarbonate by passing excess carbon dioxide in sodium chloride solution saturated with ammonia.
(ii) The ammonium bicarbonate formed reacts with sodium chloride to give sodium bi carbonate. As sodium bicarbonate has poor solubility. It gets precipitated.
(iii) The sodium bicarbonate is isolated and is heated to give sodium carbonate.
(iv) The equations involved in this process is as below.
1. `2NH_3+H_2O+CO_2to(NH_4)_2CO_3`
2. `(NH_4)_2CO_3+H_2O+CO_2to2NH_4HCO_3`
3. `NH_4HCO_3+NaCltoNH_4Cl+underset("Ammonium chloride")NaHCO_3`
4. `2NaHCO_3toNa_2CO_3+underset("Sodium carbonate")CO_2+H_2O`