Exothermic vs. Endothermic Reactions: Key Differences Explained
Exothermic reactions release heat to the surroundings; endothermic reactions absorb heat from the surroundings.
We mix them up because both involve temperature change, but the direction of heat flow is invisible. A hot pack feels warm, a cold pack feels cool—yet we rarely ask where the energy goes.
Key Differences
Exothermic: energy exits, ΔH negative, feels warm. Endothermic: energy enters, ΔH positive, feels cool. Same bonds, opposite energy flow.
Examples and Daily Life
Exothermic: combustion in lighters, hand warmers. Endothermic: instant cold packs, photosynthesis using sunlight to build sugar.
Which reaction type powers your campfire?
Combustion of wood is exothermic; it releases heat and light you feel.
Why does baking powder feel cold on the tongue?
It dissolves endothermically, pulling heat from your tongue and mouth tissues.