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The bond dissociation energy is the amount of energy required to break a bond and generate two atomic or molecular fragments, each of which has one electron from the original shared pair. This is an endothermic process. As a result, an extremely stable bond has a high bond dissociation energy, which means that additional energy must be used in order to split the link. High bond dissociation energy indicates that the bond (as well as the molecule) is low in energy and therefore stable. Bond energies are proportional to the number of bonds that exist between atoms. Despite the fact that bonds are weaker than bonds, a double bond, which consists of a and an is bond, is stronger than a single bond due to the fact that there are two bonds involved.
Enthalpy of Dissociation of a Bond
It is possible to define bond dissociation enthalpy as the standard change in enthalpy that occurs when a bond is broken via homolytic fission.The radicals that are produced as a result of the homolysis of the link are the most common.
What is the definition of Bond Dissociation Enthalpy?
The bond dissociation enthalpy of a chemical bond between two species can be used to evaluate the strength of the chemical binding between the two species. It is commonly defined as the enthalpy change of the homolytic fission of a chemical bond at absolute zero, however it is typically measured as the enthalpy change at standard conditions (298K) (0K).
Some of the most important characteristics of the concept of bond dissociation enthalpy are as follows:
It is the quantity of energy that must be supplied in order to break a chemical bond that exists between two different kinds of atoms.
Chemical bond strength can be calculated by the use of this method.
With regard to diatomic molecules in particular, it is equal to the value of bond energy.
The link between silicon and fluorine is believed to have the highest bond dissociation enthalpy of all the chemical bonds known.
Covalent bonds between atoms or molecules are believed to have low bond dissociation energy since they are formed by electrostatic attraction.
Enthalpy of Dissociation of a Bond
For diatomic molecules, as previously discussed, the bond dissociation enthalpy is equal to the bond energy, which means that the bond energy is conserved. This is due to the fact that bond energy is the average value of all the bond dissociation enthalpies of all bonds of the same type in a molecule, and bond energy is calculated as follows:
To illustrate, consider a molecule of methane from which all hydrogen atoms must be removed in order to complete the transformation. The energy required to remove the first hydrogen molecule is 105 kcal/mol, but the energy required to remove the second hydrogen molecule is 110 kcal/mol. It is calculated that the bond dissociation enthalpy of the third and fourth hydrogens is 101 kcal/mol and 81 kcal/mol, respectively, for these hydrogens. By averaging these values, it is discovered that the overall bond energy is 99 kcal/mol, which is not equivalent to any of the bond dissociation energies of the C-H bonds, as previously stated.
The Chemical Bonds with the Weakest and the Strongest Strengths
The idea of bond dissociation enthalpy can be used to identify the chemical bonds that are the weakest and the strongest. As previously noted, the link between silicon and fluorine is proven to be the strongest chemical bond ever discovered.
In a silicon tetrafluoride molecule, it is calculated that the bond dissociation energy necessary to break the first silicon-fluorine bond is 166 kcal/mol, or 166 kcal/mol. Due to the large disparity in electronegativities between silicon and fluorine atoms, as well as the fact that fluorine is the most electronegative element in the entire periodic table, this can be explained.
Moving on to neutral compounds, it is discovered that the carbon-oxygen bond in carbon monoxide has the highest strength of any known bond, with a bond dissociation energy of 257 kcal/mol. It should be noted that the carbon-carbon bond in ethyne possesses a significantly high bond dissociation energy, which is estimated to be roughly 160 kcal/mol.
Consequently, the idea of bond dissociation enthalpy has been shown to be quite beneficial in the study of thermochemistry, as previously stated.
Conclusion
From the following article we can conclude that Endothermic bond dissociation requires a certain amount of energy in order to produce two atomic or molecular fragments, each containing an electron from the original shared pair, known as the bond dissociation energy (BDE). As a result, a strong connection has a high bond dissociation energy—more energy is required to break it. A bond with a high dissociation energy indicates that the bond (and molecule) is low-energy and stable. The number of bonds between atoms affects the bond energies. However, although bonds are weaker than bonds, the presence of two bonds makes the double bond stronger than just one.
