Term: activation
https://doi.org/10.1351/goldbook.A00093

Definition:
This word is used in different senses:   Input of external energy into a chemical system is said to bring about activation of the system.   An added substance that increases the rate of a catalysed reaction is known as an activator, and the effect is called activation. The degree of activation ɛa is defined by: \[\varepsilon_{\text{a}}=\frac{v\,-\,v_{0}}{v_{0}} = \frac{v}{v_{0}} - 1\] where v 0 is the rate of the catalysed reaction in the absence of the activator and v is the rate of the catalysed reaction in the presence of the activator.  When some of the energy required for a reaction to occur is provided by a previous exothermic chemical reaction there is said to be chemical activation.  

Related Terms:
1) activator (http://doi.org/10.1351/goldbook.A00104).
2) inhibition (http://doi.org/10.1351/goldbook.I03034).
3) chemical activation (http://doi.org/10.1351/goldbook.C01017).
4) catalysis (http://doi.org/10.1351/goldbook.C00874).

Source: PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 151 (https://doi.org/10.1351/pac199668010149)

Citation: 'activation' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.A00093

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