{"term":{"id":"08147","title":"bond enthalpy","longtitle":"IUPAC Gold Book - bond enthalpy","doi":"10.1351\/goldbook.08147","code":"08147","status":"current","synonym":"<em>synonyms<\/em>: mean bond energy, mean bond enthalpy","definitions":[{"id":1,"text":"Average value of the gas-phase bond-dissociation enthalpies (usually at a temperature of \\(\\pu{298 K}\\)) for all bonds of the same type within the same chemical species.","notes":{"1":"More commonly, tabulated mean bond energies (which are really enthalpies) are values of bond enthalpies averaged over a number of selected chemical species containing that type of bond, such as \\(\\pu{414 kJ mol-1}\\) for \\(\\ce{C-H}\\) bonds in a group of \\(\\ce{R3CH}\\) (\\(\\ce{R = H}\\), alkyl)."},"exams":{"1":"For methane, the mean bond enthalpy is \\(\\pu{415.9 kJ mol-1}\\), one-fourth the enthalpy of reaction for \\[\\ce{CH4 (g) -> C (g) + 4H (g)}\\]"},"links":[{"term":"bond-dissociation enthalpies","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/08146"}],"sources":["PAC, 2022, 94, 353. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)' on page 372 (https:\/\/doi.org\/10.1515\/pac-2018-1010)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/08147\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/08147\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/08147\/plain"},"citation":"Citation: 'bond enthalpy' 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.08147","license":"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.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"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.","accessed":"2026-05-08T10:39:09+00:00"}}