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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