Common
Bond dissociation energy
Standard enthalpy change when a chemical bond is cleaved by homolysis
Bond dissociation energy
The bond dissociation energy (BDE, D0, or DH°) is one measure of the strength of a chemical bond A−B. It can be defined as the standard enthalpy change when A−B is cleaved by homolysis to give fragments A and B, which are usually radical species. The enthalpy change is temperature-dependent, and the bond dissociation energy is often defined to be the enthalpy change of the homolysis at 0 K (absolute zero), although the enthalpy change at 298 K (standard conditions) is also a frequently encountered parameter. As a typical example, the bond dissociation energy for one of the C−H bonds in ethane (C2H6) is defined as the standard enthalpy change of the process CH3CH2−H → CH3CH2• + H•, DH°298(CH3CH2−H) = ΔH° = 101.1(4) kcal/mol = 423.0 ± 1.7 kJ·mol⁻¹ = 4.40(2) eV (per bond). To convert a molar BDE to the energy needed to dissociate the bond per molecule, the conversion factor 23.060 kcal/mol (96.485 kJ/mol) for each eV can be used. A variety of experimental techniques, including spectrometric...
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