Bond Enthalpy Definition in Chemistry

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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on August 08, 2019

Bond enthalpy is the enthalpy change when one mole of bonds are broken in a substance at 298 K. Bond enthalpy is also known as bond-dissociation enthalpy, bond strength, or average bond energy. The higher its value, the stronger the bond and the more energy required to break it.

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Bond Energy Definition in Chemistry
By Anne Marie Helmenstine, Ph.D.

Typical units of bond enthalpy are kilocalories per mole (kcal/moll) and kilojoules per mole (kJ/mol). Example values in 410 kJ/mol for the C-H bond and 945 kJ/mol for the N≡N bond. From this, it's easy to see triple bonds are much stronger than single bonds.

Bond enthalpy refers to the enthalpy change of one particular bond in a molecule.

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Helmenstine, Anne Marie, Ph.D. "Bond Enthalpy Definition in Chemistry." ThoughtCo, Aug. 28, 2020, thoughtco.com/definition-of-bond-enthalpy-604839. Helmenstine, Anne Marie, Ph.D. (2020, August 28). Bond Enthalpy Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-bond-enthalpy-604839 Helmenstine, Anne Marie, Ph.D. "Bond Enthalpy Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-bond-enthalpy-604839 (accessed April 24, 2024).