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| 1. |
Prepration method of washing soda |
| Answer» Solvay Process- preparation of sodium carbonate(washing soda)Step 1: Purification of Brine Concentrated brine is obtained by the process of evaporation and impurities like calcium, magnesium etc are removed by the process called precipitation. The concentrated brine solution undergoes filtration and is mixed with ammonia in the ammonia tower and the ammonia tower gets cooled.Step 2: Formation of sodium hydrogen carbonate In a carbonate tower, carbon dioxide is passed through ammoniated brine solution.NH3(aq)+CO2(g)+NaCl(aq)+H2O→NaHCO3(s)+NH4Cl(aq)Step 3: Formation of sodium carbonate Sodium Bicarbonate formed is obtained from the tower and is heated at a temperature of 300°C. Hence formations of sodium carbonate takes place. 2NaHCO3→Na2CO3+CO2+H2OStep 4: Recovery of ammonia Ammonia can be recovered by treating the solution of NH4Cl with Ca (OH)2. This ammonia is again used in Solvay process and CaCl2 is obtained as a by-product. 2NH4Cl+Ca(OH)2→2NH3+CaCl2+H2O | |