Difference Between Endothermic and Exothermic Reactions
Chemical reactions can either absorb energy or release energy, and this determines whether they are endothermic or exothermic. Understanding this distinction is important in chemistry, biology, and everyday applications.
1. Definition
- Endothermic Reaction: A reaction that absorbs energy (usually heat) from the surroundings.
- Exothermic Reaction: A reaction that releases energy (usually heat) to the surroundings.
2. Energy Change
- Endothermic: Energy of products is higher than the reactants. Energy is taken in.
- Exothermic: Energy of products is lower than the reactants. Energy is released.
3. Temperature Change
- Endothermic: Surroundings become cooler because energy is absorbed.
- Exothermic: Surroundings become warmer because energy is released.
4. Examples
- Endothermic Reactions: Photosynthesis, melting ice, cooking an egg.
- Exothermic Reactions: Combustion of fuels, respiration, condensation of steam.
5. Energy Diagram
- Endothermic: Reactants → Products; energy goes in.
- Exothermic: Reactants → Products; energy comes out.
Summary Table:
| Feature | Endothermic Reaction | Exothermic Reaction |
|---|---|---|
| Definition | Absorbs energy from surroundings | Releases energy to surroundings |
| Energy of Products | Higher than reactants | Lower than reactants |
| Temperature Change | Surroundings get cooler | Surroundings get warmer |
| Examples | Photosynthesis, melting ice | Combustion, respiration |
| Energy Flow | Into the system | Out of the system |
Key Point:
- Endothermic: Energy absorbed, surroundings cool.
- Exothermic: Energy released, surroundings warm.