Decomposition Reactions
📚 Key Concepts
🔹 Real-Life Example
When you leave hydrogen peroxide (the liquid used to clean wounds) in sunlight, it slowly breaks down into water and oxygen gas. You might notice bubbles forming – that’s oxygen escaping! This is like a couple breaking up into two separate individuals – one compound splitting into simpler substances.
Decomposition Reaction: Reactions in which one compound decomposes in two or more compounds or element are known as decomposition reaction. Decomposition reaction is just opposite of combination reaction.
🧪 Important Formulas
🔸 General Formula
AB → A + B
Where AB is the reactant, and A and B are the products.
🔸 Types of Decomposition
1. Thermal Decomposition (Heat)
- CaCO₃ → CaO + CO₂ (heating limestone)
2. Electrolytic Decomposition (Electricity)
- 2H₂O → 2H₂ + O₂ (electrolysis of water)
3. Photolytic Decomposition (Light)
- 2AgCl → 2Ag + Cl₂ (silver chloride in sunlight)
🔹 Energy Requirements
Most decomposition reactions are endothermic – they require energy input to break bonds:
- Heat: Thermal decomposition
- Light: Photolysis
- Electricity: Electrolysis
🔍 Advanced: Photography Connection
Silver chloride’s decomposition in light is the basis of traditional black and white photography. When light hits photographic film coated with silver chloride, it decomposes to form dark silver metal, creating the image.