Cân bằng các phản ứng oxi hóa – khử sau

a) H+1Cl−1  +  Pb+4O−22   →  Pb+2Cl−12  +  Cl02  +  H+12O−2

Pb+4   +2e  →  Pb  +2Cl−1   →  Cl0  +1e

1  × 2  × Pb+4   +2e  →  Pb  +2Cl−1   →  Cl0  +1e

 

⇒ Pb+4   +  2Cl−1  →  Pb+2  + 2Cl0

4HCl + PbO₂ → PbCl₂ + Cl₂ + 2H₂O

b) K+1Mn+7O−24  +  H+1Cl−1  →  K+1Cl−1   +  Mn+2Cl−12  +  Cl02  +  H+12O−2

Mn+7  +5e  →  Mn+2Cl−1   →  Cl0   +1e

1 × 5 ×Mn+7  +5e  →  Mn+2Cl−1   →  Cl0   +1e

 

⇒  Mn+7  +  5Cl−1  →  Mn+2  +  5Cl0

⇒ 2Mn+7  +  10Cl−1  →  2Mn+2  +  10Cl0

2KMnO₄ + 16HCl → 2KCl + 2MnCl₂ + 5Cl₂ + 8H₂O