7
CBSE Marks
★★★★★
Difficulty
10
Topics
High
Board Weight
Topics Covered
10 key topics in this chapter
Chemical Reactions: Characteristics
Chemical Equations
Balancing Chemical Equations
Types: Combination Reaction
Types: Decomposition Reaction
Types: Displacement Reaction
Types: Double Displacement Reaction
Oxidation & Reduction
Redox Reactions
Corrosion & Rancidity
Study Resources
Key Formulas & Reactions
| Formula / Reaction / Rule | Expression |
|---|---|
| Combination | \(A + B → AB\) |
| Decomposition | \(AB → A + B (heat / light / electricity)\) |
| Displacement | \(A + BC → AC + B (A more reactive)\) |
| Double Displacement | \(AB + CD → AD + CB (precipitate formed)\) |
| Redox (general) | \(Oxidising agent gains e⁻; Reducing agent loses e⁻\) |
| Rusting of Iron | \(4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O\) |
Important Points to Remember
A chemical equation is balanced to satisfy the Law of Conservation of Mass — atoms of each element must be equal on both sides.
Combination: A + B → AB. Decomposition: AB → A + B. Displacement: A + BC → AC + B. Double displacement: AB + CD → AD + CB.
Oxidation = loss of electrons / gain of oxygen / loss of hydrogen. Reduction = opposite. They always occur together (Redox).
Corrosion (rusting of iron) and rancidity (oxidation of fats/oils) are slow chemical reactions with real-life impact.