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The term bond-dissociation energy is similar to the related notion of bond-dissociation enthalpy (or bond enthalpy), which is sometimes used interchangeably.However, some authors make the distinction that the bond-dissociation energy (D 0) refers to the enthalpy change at 0 K, while the term bond-dissociation enthalpy is used for the enthalpy change at 298 K (unambiguously denoted DH° 298).
The bond energy for H 2 O is the average energy required to break each of the two O–H bonds in sequence: Although the two bonds are the equivalent in the original symmetric molecule, the bond-dissociation energy of an oxygen–hydrogen bond varies slightly depending on whether or not there is another hydrogen atom bonded to the oxygen atom.
This sum will have a maximum at , representing the point of bond dissociation; summing over all the differences up to this point gives the total energy required to dissociate the molecule, i.e. to promote it from the ground state to an unbound state. This can be written:
Bond energies and bond-dissociation energies are typically in the range of a few eV per bond. The bond-dissociation energy of a carbon-carbon bond is about 3.6 eV. Molecular level: Electron binding energy; Ionization energy Electron binding energy, more commonly known as ionization energy, [3] is a measure of the energy required to free an ...
The bond-dissociation energy of a bond is the amount of energy required to cleave the bond homolytically. This enthalpy change is one measure of bond strength . The triplet excitation energy of a sigma bond is the energy required for homolytic dissociation, but the actual excitation energy may be higher than the bond-dissociation energy due to ...
Bond cleavage is also possible by a process called heterolysis. The energy involved in this process is called bond dissociation energy (BDE). [2] BDE is defined as the "enthalpy (per mole) required to break a given bond of some specific molecular entity by homolysis," symbolized as D. [3]
Bond dissociation energy for the carbon monoxide (CO) triple bond, alternatively stated: 1072 kJ/mol; 11.11eV per molecule. [ 21 ] This is the strongest chemical bond known.
Given any three values and the fourth can be calculated. Its important to note that the fourth reaction in the series is an inverted homolytic bond cleavage stated in terms of free energy. The chemical transformation for the associated -ΔG˚ is the same it would be for a bond dissociation energy (BDE). However, the -ΔG˚ is not a BDE, since ...