Solvay process

The Solvay Process is a chemical process which uses ammonia to convert salt and calcium carbonate into sodium carbonate and calcium chloride.

1. Roast calcium carbonate (Limestone) to give calcium oxide and carbon dioxide:

   CaCO₃ → CaO + CO₂ // roast

2. Bubble carbon dioxide through a mixture of aqueous ammonia and salt in water, giving ammonium chloride and sodium bicarbonate

   NaCl + NH₃ + H₂O + CO₂ → NaHCO₃↓(s) + NH₄Cl(aq)

3. Filter off the sodium bicarbonate
4. Recombine the calcium oxide with the aqueous ammonium chloride giving ammonia and calcium chloride.

   2 NH₄Cl(aq) + CaO → 2 NH₃ + CaCl₂ + H₂O