exothermic reaction
Definition
- Noun:
- A chemical reaction that releases energy, usually in the form of heat, into its surroundings. The total energy of the products is lower than the total energy of the reactants.
Usage
The term "exothermic reaction" is used in scientific contexts, primarily chemistry and physics, to describe a process where heat is a product of the reaction. It is the opposite of an endothermic reaction, which absorbs heat.
Examples
- The combustion of wood in a fire is a classic example of an exothermic reaction.
- In a hand warmer, an exothermic reaction provides heat through the crystallization of a supersaturated solution.
- The neutralization of an acid with a base is typically an exothermic reaction.
Advanced Usage
- In Thermodynamics: The concept is formalized by stating that for an exothermic process at constant pressure, the change in enthalpy (ΔH) is negative (ΔH < 0).
- In Biology: Cellular respiration is a series of metabolic exothermic reactions that release energy used to produce ATP.
Variants and Related Words
- Exothermic (adjective): Describing the property of releasing heat.
- The reaction is highly exothermic.
- Exothermically (adverb): Describing the manner in which heat is released.
- The compounds reacted exothermically.
- Endothermic Reaction (noun): The antonym; a reaction that absorbs heat from its surroundings (ΔH > 0).
Synonyms
- Heat-releasing reaction
- Exergic reaction (less common)
Related Phrases
- Heat of reaction: The amount of heat absorbed or released during a chemical reaction.
- Enthalpy change (ΔH): The thermodynamic quantity equivalent to the total heat content of a system, used to formally denote whether a reaction is exothermic (negative ΔH) or endothermic (positive ΔH).
Noun
-
a chemical reaction accompanied by the evolution of heat
