Exothermic process
thermodynamic reaction
In thermodynamics, an exothermic process (from Ancient Greek έξω (éxō) 'outward' and θερμικός (thermikós) 'thermal') is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen). The term exothermic was coined by 19th-century French chemist Marcellin Berthelot.
The opposite of an exothermic process is an endothermic process, one that absorbs energy, usually in the form of heat. The concept is frequently applied in the physical sciences to chemical reactions where chemical bond energy is converted to thermal energy (heat).
Two types of chemical reactions
Exothermic and endothermic describe two types of chemical reactions or systems found in nature, as follows:
Exothermic
An exothermic reaction occurs when heat is released to the surroundings. According to the IUPAC, an exothermic reaction is "a reaction for which the overall standard enthalpy change ΔH° is negative". Some examples of exothermic process are fuel combustion, condensation and nuclear fission, which is used in nuclear power plants to release large amounts of energy.
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This entry incorporates text from “Exothermic process” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.