1) Na + 2H₂O = 2NaOH + H₂;
Na⁰ + 2H₂O = 2Na⁺ + 2OH⁻ + H₂.
2) NaOH + HCl = NaCl + H₂O;
Na⁺ + OH⁻ + H⁺ + Cl⁻ = Na⁺ + Cl⁻ + H₂O;
OH⁻ + H⁺ = H₂O.
3) 2NaOH + CO₂ = Na₂CO₃ + H₂O;
2Na⁺ + 2OH⁻ + CO₂ = 2Na⁺ + CO₃²⁻ + H₂O;
2OH⁻ + CO₂ = CO₃²⁻ + 2H₂O.
4) Na₂CO₃ + SO₂ = Na₂SO₃ + CO₂;
2Na⁺ + CO₃²⁻ + SO₂ = 2Na⁺ + SO₃²⁻ + CO₂;
CO₃²⁻ + SO₂ = SO₃²⁻ + CO₂.