Class 10 CBSE Science
Chapter 1: Chemical Reactions and Equations – Quick Revision Notes
1. Basic Concepts
• Chemical Reaction: A process in which one or more substances (reactants) are converted into new
substances (products).
• Example: Magnesium + Oxygen → Magnesium Oxide.
• Word Equation Example: Magnesium + Oxygen → Magnesium Oxide.
• Skeletal Chemical Equation: Mg + O■ → MgO (not balanced).
• Balanced Chemical Equation: 2Mg + O■ → 2MgO.
2. Types of Chemical Reactions
• Combination Reaction: Two or more substances combine to form a single product. Example: CaO +
H■O → Ca(OH)■.
• Decomposition Reaction: A single compound breaks into two or more substances. Example: CaCO■
→ CaO + CO■.
• Displacement Reaction: A more reactive element displaces a less reactive one. Example: Zn +
CuSO■ → ZnSO■ + Cu.
• Double Displacement Reaction: Exchange of ions between two compounds. Example: Na■SO■ +
BaCl■ → BaSO■ + 2NaCl.
3. Energy Changes in Reactions
• Exothermic Reaction: Releases heat. Example: Combustion of methane.
• Endothermic Reaction: Absorbs heat. Example: Thermal decomposition reactions.
4. Effects of Oxidation
• Corrosion: Slow eating away of metals due to reaction with environment (e.g., rusting of iron).
• Rancidity: Oxidation of oils and fats causing bad smell and taste in food.
Tip: Always balance chemical equations and remember reaction types for exams.
Chapter 1: Chemical Reactions and Equations – Quick Revision Notes
1. Basic Concepts
• Chemical Reaction: A process in which one or more substances (reactants) are converted into new
substances (products).
• Example: Magnesium + Oxygen → Magnesium Oxide.
• Word Equation Example: Magnesium + Oxygen → Magnesium Oxide.
• Skeletal Chemical Equation: Mg + O■ → MgO (not balanced).
• Balanced Chemical Equation: 2Mg + O■ → 2MgO.
2. Types of Chemical Reactions
• Combination Reaction: Two or more substances combine to form a single product. Example: CaO +
H■O → Ca(OH)■.
• Decomposition Reaction: A single compound breaks into two or more substances. Example: CaCO■
→ CaO + CO■.
• Displacement Reaction: A more reactive element displaces a less reactive one. Example: Zn +
CuSO■ → ZnSO■ + Cu.
• Double Displacement Reaction: Exchange of ions between two compounds. Example: Na■SO■ +
BaCl■ → BaSO■ + 2NaCl.
3. Energy Changes in Reactions
• Exothermic Reaction: Releases heat. Example: Combustion of methane.
• Endothermic Reaction: Absorbs heat. Example: Thermal decomposition reactions.
4. Effects of Oxidation
• Corrosion: Slow eating away of metals due to reaction with environment (e.g., rusting of iron).
• Rancidity: Oxidation of oils and fats causing bad smell and taste in food.
Tip: Always balance chemical equations and remember reaction types for exams.
