03134 IUPAC Gold Book - intrinsic activation energy 10.1351/goldbook.I03134 I03134 current quantity 1 If \(E_{\rm{a,1}}\) and \(E_{\rm{a,- 1}}\) are the activation energies for a reaction in forward and reverse directions, the lesser of the two is sometimes called the intrinsic activation energy. It is the activation energy for the reaction in the exothermic direction. activation https://goldbook.iupac.org//terms/view/A00093 activation energies https://goldbook.iupac.org//terms/view/A00102 PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 170 (https://doi.org/10.1351/pac199668010149) https://goldbook.iupac.org/terms/view/I03134/html https://goldbook.iupac.org/terms/view/I03134/json https://goldbook.iupac.org/terms/view/I03134/plain Citation: 'intrinsic activation energy' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.I03134 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-08-05T05:38:30+00:00