exothermic reaction
chemical reaction that releases energy by light or heat; opposite of an endothermic reaction
AI overview
An exothermic reaction is a chemical process that releases energy in the form of heat or light. These reactions matter because they power many everyday phenomena, from burning fuel and cooking food to hand warmers and fireworks.
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Article
The thermite reaction is famously exothermic. The reduction of iron(III) oxide by aluminium releases sufficient heat to yield molten iron. In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative." Exothermic reactions usually release stored energy as heat. The term is often confused with exergonic reaction, which IUPAC defines as "... a reaction for which the overall standard Gibbs energy change ΔG is negative." A strongly exothermic reaction will usually also be exergonic because ΔH makes a major contribution to ΔG. Most of the spectacular chemical reactions that are demonstrated in classrooms are exothermic and exergonic. The opposite is an endothermic reaction, which usually takes up heat and is driven by an entropy increase in the system.
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