Question

Describe the manufacture of sodium carbonate by Solvay process. 

Answer 1

Step1: preparation of ammonical brine Ammonia is passed through a Saturated solution of sodium chloride in water , ammoniacal brine is formed .It is cooled to 30°C 

Step 2: carbonation Carbon dioxide gas is passed through ammoniacal brine ,where ammonium carbonate and sodiumbicarbonate.

NH₃ + H₂O + CO₂ → (NH₄)₂CO₃

(NH₄)₂CO₃ + H₂O + CO₂ → 2NH₄HCO₃

NH₄HCO₃ + NaCl → NH₄Cl + NaHCO₃.

Sodium bi carbonate crystal separates and these are heated to give sodium carbonate.

2NaHCO₃→ Na₂CO₃ + CO₂+H₂O

Step 3: Recovery of ammonia Ammonia is recovered when the solution containing ammonium chloride is treated with Ca(OH)₂.

2 NH₄Cl + Ca(OH)₂ → CaCl₂ + 2NH₃ + H₂O