Sodium carbonate is obtained by Solvay Ammonia process. The Solvay ammonia process includes:

⇒ CO₂ is passed through brine (i.e., a concentrated solution of NaCl) saturated with ammonia.

⇒ Sodium bicarbonate (NaHCO₃) is formed which is sparingly soluble and gets precipitated.

⇒ NaHCO₃ on further heating gives sodium carbonate (Na₂CO₃).

Overall reaction:

Note: Solvay ammonia process is used in the manufacture of sodium bicarbonate. The working of Solvay ammonia process is given below: