$word_{count}$: 230

NaOH (caustic soda): Manufactured by Castner-Kellner process (electrolysis of brine with Hg cathode → Na-Hg amalgam → amalgam + H2O → NaOH + H2 + Hg). White, deliquescent, strong base. Used in soap making, petroleum refining, paper industry.

Na2CO3 $\frac{soda ash}{washing soda}$: Made by Solvay process. Step 1: NaCl + NH3 + CO2 + H2O → NaHCO3 (precipitates — least soluble) + NH4Cl. Step 2: 2NaHCO3 → Na2CO3 + H2O + CO2. NH3 recovered: 2NH4Cl + Ca(OH)2 → 2NH3 + CaCl2 + 2H2O. Net: 2NaCl + CaCO3 → Na2CO3 + CaCl2. Cannot make K2CO3 (KHCO3 too soluble to precipitate).

Na2CO3.10H2O is washing soda; loses water stepwise to Na2CO3 (soda ash). Used for water softening: CaSO4 + Na2CO3 → CaCO3(ppt) + Na2SO4.

NaHCO3 (baking soda): Mild base, decomposes on heating (2NaHCO3 → Na2CO3 + H2O + CO2). Applications: baking powder (with tartaric acid), antacid, soda-acid fire extinguisher (NaHCO3 + H2SO4 → Na2SO4 + H2O + CO2).