Bond energy is the amount of energy necessary to form or break a molecule. However, when the same two elements are combined the amount of energy involved can vary slightly depending on how many other elements are also present within the molecule. Because of this slight variation, it is sometimes useful to calculate the average bond energy that exists between two or more elements.
Select a molecule of which your specific bond is only a part. For example, if you are looking for the bond energy found in a C-C bond you might choose the molecule methane (CH4) or propane (C3H8) since both of these contain C.
Determine the total bond energy of the entire molecule. If this is not already given, you can calculate it by adding up all of the individual bond energies of the elemental compounds that comprise the molecule.
Isolate the bond energy of your specific bond. This is done by taking the total bond energy of the entire molecule and subtracting from it the bond energies that do not belong to your specific bond. If there is more than one of your specific bond in the molecule, divide the isolated bond energy of your specific bond by the number of times this bond is found in the molecule.
Repeat steps 1-3 with as many molecules as desired. The greater the variety of molecules you use, the more accurate the final bond energy average will be.
Add up the totals of all the isolated bond energies of your specific bond and divide by the number of totals that you added. The result is the average bond energy of your chosen bond.