An exothermic reaction is a chemical reaction that releases energy into the surroundings, usually in the form of heat, light, or sometimes sound.
Key Features of Exothermic Reactions
- Energy Release
- Energy of the products is lower than the energy of the reactants.
- The excess energy is given out to the surroundings.
- Temperature Change
- The surroundings become warmer because heat is released.
- Example: A beaker feels warm during an exothermic reaction.
- Energy Profile
- On an energy diagram, the curve goes downwards as energy is released.
- Examples
- Combustion: Burning of fuels (e.g., CH₄ + 2O₂ → CO₂ + 2H₂O + energy).
- Respiration: Breakdown of glucose in cells releases energy.
- Neutralization: Acid + Base → Salt + Water (heat released).
- Explosions: Rapid exothermic reactions release large amounts of heat, light, and sound.
- Applications
- Used in hand warmers, fireworks, and engines (where fuel combustion releases energy).