СuSO₄ + Na₂S = CuS↓ + Na₂SO₄
Сu²⁺ + SO₄²⁻ + 2Na⁺ + S²⁻ = CuS↓ + 2Na⁺ + SO₄²⁻
Сu²⁺ + S²⁻ = CuS↓
3Ba(OH)₂ + 2FeCl₃ = 2Fe(OH)₃↓ + 3BaCl₂
3Ba²⁺ + 2OH⁻ + 2Fe³⁺ + 6Cl⁻ = 2Fe(OH)₃↓ + 3Ba²⁺ + 6Cl⁻
2OH⁻ + 2Fe³⁺ = 2Fe(OH)₃↓
NaHCO₃ + NaOH = Na₂CO₃ + H₂O
Na⁺ + HCO₃⁻ + Na⁺ + OH ⁻ = 2Na⁺ + CO₃²⁻ + H₂O
HCO₃⁻ + OH ⁻ = CO₃²⁻ + H₂O