How is Sodium Carbonate (Washing Soda), Na2CO3·10H2O manufactured by “Solvay Process”
Principle-- In this process, advantage is taken of the low solubility of sodium hydrogencarbonate whereby it gets precipitated in the reaction of sodium chloride with ammonium hydrogencarbonate. The latter is prepared by passing CO2 to a concentrated solution of sodium chloride saturated with ammonia, where ammonium carbonate followed by ammonium hydrogencarbonate are formed. The equations for the complete process may be written as :
Sodium hydrogencarbonate crystal separates. These are heated to give sodium carbonate.
Recovery of some raw material--In this process NH3 is recovered when the solution containing NH4Cl is treated with Ca(OH)2. Calcium chloride is obtained as a by-product.