2.4 Bond Enthalpy

What is bond enthalpy?

Bond enthalpy is the energy possessed by any given bond; each bond type has a different energy associated with it which can be found on a standardized table

what are the two factors affecting bond enthalpy

the length of the bond → the longer the bond, the lower the enthalpy

the number of bonds → the more bonds, the higher the enthalpy

how can we use bond enthalpy to find the net enthalpy of a reaction

We compare the sum of the bond energies of the reactants and products, and their overall difference will be the change of enthalpy.

ΔHr = ∑ΔH(bonds broken) - ∑ΔH(bonds formed)

What must be done in order to properly calculate the ΔH using bond enthalpy

• you must draw the molecules and identify all the different bonds, different number of bonds must be identified seperately