Class 11 Chemistry The S Block Elements Preparation of washing soda by solvay process

Preparation of washing soda by solvay’s process

  • The Solvay process is extensively used for industrial preparation of sodium carbonate (soda ash). The process is named after Ernest Solvay who developed the process during the 1860s.
  • Carbon dioxide reacts with the dissolved ammonia to form ammonium carbonate followed by ammonium hydrogen carbonate.

2NH3 +H2O + CO2 ---> (NH4)2CO3

(Ammonia)                 (Ammonium Carbonate)


(NH4)2CO3 + H2O + CO2 --> NH4HCO3

(Ammonium Carbonate)       (Ammonium hydrogen carbonate)


NH4HCO3       +          NaCl  -->   NH4Cl     +    NaHCO3


Sodium hydrogen carbonate crystal separates. These are heated to give sodium carbonate.

     2 NaHCO3       -->      Na2CO3 + CO2 + H2O

But this process cannot be used to prepare potassium due to the high solubility of potassium bicarbonate and hence difficult to be precipitated by adding ammonium bicarbonate to a saturated solution of potassium

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