Q.Write the chemical equations for the reactions involved in solvay process of preparation of sodium carbonate.

Step 1. Ammonia gas is first dissolved and carbonated in the presence of water to form ammonium carbonate: 2NH₃ + H₂O + CO₂ → (NH₄)₂CO₃.

Step 2. Passing further excess carbon dioxide converts this to ammonium bicarbonate: (NH₄)₂CO₃ + H₂O + CO₂ → 2NH₄HCO₃.

Step 3. This ammonium bicarbonate solution is reacted with sodium chloride (as brine saturated with ammonia); the sodium bicarbonate formed is only sparingly soluble and precipitates out, while ammonium chloride stays in solution: NH₄HCO₃ + NaCl → NH₄Cl + NaHCO₃.

Step 4. The precipitated sodium bicarbonate is filtered off and heated, decomposing to give the final product, sodium carbonate: 2NaHCO₃ →(Δ)→ Na₂CO₃ + CO₂ + H₂O.

Step 5. (The ammonia is recycled by treating the leftover ammonium chloride solution with calcium hydroxide, regenerating NH₃ with calcium chloride as a by-product, though this recovery step is not itself part of the four core equations asked for.)

Write out, in order, the four core reactions of the Solvay process: carbonation of ammonia, conversion to bicarbonate, metathesis with NaCl to precipitate NaHCO3, and thermal decomposition of NaHCO3 to Na2CO3.

• Omitting the intermediate ammonium-bicarbonate step and trying to react ammonium carbonate directly with NaCl -- the process specifically goes through NH4HCO3, since it is this species that reacts with NaCl to precipitate NaHCO3.
• Forgetting to balance the final decomposition equation with 2 mol of NaHCO3 (one CO2 and one H2O are produced per 2 NaHCO3, not per 1).