Last Updated: 11 May 2026Verified for JEE 2027
ChemistryJEE & NEET
Difference Between Exothermic Reaction and Endothermic Reaction
Chemical reactions either release or absorb energy. Exothermic reactions release heat to surroundings, while endothermic reactions absorb heat from surroundings.
Exothermic Reaction vs Endothermic Reaction — Comparison Table
| Aspect | Exothermic Reaction | Endothermic Reaction |
|---|---|---|
| Heat | Released to surroundings | Absorbed from surroundings |
| ΔH | Negative (ΔH < 0) | Positive (ΔH > 0) |
| Temperature | Surroundings get warmer | Surroundings get cooler |
| Energy level | Products lower than reactants | Products higher than reactants |
| Bond energy | Bond formation > Bond breaking | Bond breaking > Bond formation |
| Example | Combustion, neutralization | Photosynthesis, melting ice |
Key Points to Remember
Exothermic: combustion of fuels, acid-base neutralization, crystallization
Endothermic: thermal decomposition, photosynthesis, evaporation
ΔG = ΔH - TΔS determines spontaneity, not ΔH alone
Hess's Law: ΔH is independent of the path of the reaction
Exam Relevance
This topic falls under Thermodynamics in Chemistry for both JEE and NEET. Questions on the difference between exothermic reaction and endothermic reaction appear frequently in competitive exams, both as direct MCQs and as part of numerical/assertion-reason problems.
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