Difference between revisions of "Homolytic Bond Dissociation Energies"
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| − | Homolytic bond dissociation energies or just bond dissociation energies (BDE) is a measure of a particular bond strength. For example, the BDE for the C-C bond in H<sub>3</sub>C-CH<sub>3</sub> --> | + | Homolytic bond dissociation energies or just bond dissociation energies (BDE) is a measure of a particular bond strength. For example, the BDE for the C-C bond in H<sub>3</sub>C-CH<sub>3</sub> --> H<sub>3</sub>C• + •CH<sub>3</sub> can be calculated using the calculated enthalpies of formation (ΔH<sub>f</sub>) using the following method: |
| − | Using WebMO/Gaussian to calculate the | + | Using WebMO/Gaussian to calculate the ΔH<sub>f</sub>(H<sub>3</sub>C-CH<sub>3</sub>), returns the following: |
:[[File:Screen Shot 2021-04-07 at 8.13.05 AM.png|400px]] | :[[File:Screen Shot 2021-04-07 at 8.13.05 AM.png|400px]] | ||
| − | The energy is reported in units of Hartree, -79.2287548119 Hartree | + | The energy, ie. ΔH<sub>f</sub>(H<sub>3</sub>C-CH<sub>3</sub>) is reported in units of Hartree, -79.2287548119 Hartree |
| − | Using WebMO/Gaussian to calculate the | + | Using WebMO/Gaussian to calculate the ΔH<sub>f</sub>(CH<sub>3</sub>•), returns the following: |
:[[File:Screen Shot 2021-04-07 at 8.13.05 AM.png|400px]] | :[[File:Screen Shot 2021-04-07 at 8.13.05 AM.png|400px]] | ||
| − | The energy is reported in units of Hartree, -39.5589916118 Hartree | + | The energy, ie ΔH<sub>f</sub>(CH<sub>3</sub>•) is reported in units of Hartree, -39.5589916118 Hartree |
| + | |||
| + | :ΔH<sub>rxn</sub> = ΔH<sub>f</sub>(Products) - ΔH<sub>f</sub>(Reactants) | ||
| + | :ΔH<sub>rxn</sub> = 2*ΔH<sub>f</sub>(CH<sub>3</sub>•) - H<sub>f</sub>(H<sub>3</sub>C-CH<sub>3</sub>) | ||
| + | :ΔH<sub>rxn</sub> = 2*-39.5589916118 - (-79.2287548119) | ||
| + | :ΔH<sub>rxn</sub> = 0.110771588 Hartree = 290.830826448 kJ/mol | ||
Revision as of 13:27, 7 April 2021
Homolytic bond dissociation energies or just bond dissociation energies (BDE) is a measure of a particular bond strength. For example, the BDE for the C-C bond in H3C-CH3 --> H3C• + •CH3 can be calculated using the calculated enthalpies of formation (ΔHf) using the following method:
Using WebMO/Gaussian to calculate the ΔHf(H3C-CH3), returns the following:
The energy, ie. ΔHf(H3C-CH3) is reported in units of Hartree, -79.2287548119 Hartree
Using WebMO/Gaussian to calculate the ΔHf(CH3•), returns the following:
The energy, ie ΔHf(CH3•) is reported in units of Hartree, -39.5589916118 Hartree
- ΔHrxn = ΔHf(Products) - ΔHf(Reactants)
- ΔHrxn = 2*ΔHf(CH3•) - Hf(H3C-CH3)
- ΔHrxn = 2*-39.5589916118 - (-79.2287548119)
- ΔHrxn = 0.110771588 Hartree = 290.830826448 kJ/mol