Five reactions with elements that are reduced and oxidized have been presented below;
What are the reduced and oxidized elements of the reaction?
Reaction Oxidized Reduced Oxidizing Reduction
Element Element Agent Agent
2C₂H₂+5O₂ →2H₂O+4CO₂ C O O₂ C₂H₂
2Sr + O₂ → 2SrO Sr O O₂ Sr
2Cs+Br₂ → 2CsBr Br Cs Br₂ Cs
2Li + S → Li₂S S Li S Li
4Fe+30₂ → 2Fe₂O₃ Fe O O₂ Fe
2Na + 2H₂O→ 2NaOH+H₂ H Na H₂O Na
Cl₂ + 2NaBr → 2NaCl + Br₂ Br Cl Cl₂ NaBr
1. For reaction ⇒ Fe²⁺ + MnO₄ → Fe³⁺ + Mn²⁺
Oxidation Numbers:
- Fe²⁺: Fe is +2
- MnO₄⁻: Mn is +7 (since O is typically -2, and there are 4 O atoms)
- Fe³⁺: Fe is +3
- Mn²⁺: Mn is +2
Half-Reactions and Balancing
Oxidation half-reaction:
- Fe²⁺ → Fe³⁺ + e⁻ (Already balanced)
Reduction half-reaction:
- MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O
2. For reaction ⇒ Mn²⁺ + BiO₃ → Bi²⁺ + MnO₄
Oxidation Numbers:
- Mn²⁺: Mn is +2
- BiO₃⁻: Bi is typically +3 (considering O is -2)
- Bi³⁺: Bi is +3
- MnO₄⁻: Mn is +7 (since O is -2, and there are 4 O atoms)
Half-Reactions and Balancing
Oxidation Half-Reaction:
Reduction half-reaction:
- BiO₃⁻ + 6H⁺ + 3e⁻ → Bi³⁺ + 3H₂O (balanced)
3. For reaction ⇒ NH₃ + NO₂ → N₂ + H₂O
Oxidation Numbers:
- NH₃: N is -3 (H is +1)
- NO₂: N is +4 (O is -2)
- N₂: N is 0 (elemental form)
- H₂O: O is -2, H is +1
Half-Reactions and Balancing
Oxidation Half-Reaction:
- NH₃ → N₂ + 6H⁺ + 6e⁻ (balanced)
Reduction half-reaction:
- NO₂ + 4H⁺ +3e⁻ → N₂ +2H₂