Cheat sheet · Class 11 · CBSE · Science Chemistry
Redox Reactions cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 11 · Chemistry
Cheat sheet
Chapter 7Redox Reactions
OIL RIG — Oxidation Is Loss, Reduction Is Gain (of electrons).
1. Definitions
| Basis | Oxidation | Reduction |
|---|---|---|
| Electrons | lost | gained |
| Oxidation number | increases | decreases |
| Classical | add O / remove H | add H / remove O |
Oxidising agent gets reduced; reducing agent gets oxidised.
2. Oxidation Number Rules
- Element in free state: 0.
- O is −2 (peroxides −1, OF₂ +2); H is +1 (metal hydrides −1).
- F always −1; alkali metals +1, alkaline earth +2.
- Sum = 0 for a molecule, = charge for an ion.
3. Types of Redox Reactions
Combination
C + O₂ → CO₂
Decomposition
2H₂O → 2H₂ + O₂
Displacement
Zn + CuSO₄ → ZnSO₄ + Cu
Disproportionation
Same element oxidised and reduced: 2H₂O₂ → 2H₂O + O₂
4. Balancing
- Oxidation-number method: equalise increase and decrease.
- Half-reaction method: balance atoms, then O with H₂O, H with H⁺ (or OH⁻ in base), then charge with e⁻.
5. Key Points
- Electrochemical series: higher reduction potential ⇒ stronger oxidant.
- F₂ is the strongest oxidising agent.
- Li is the strongest reducing agent in solution.
- Electrons lost = electrons gained.
Remember: OIL RIG | O.N. rules | half-reaction balancing
Redox Reactions: questions and notes
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