Bond Enthalpy and Energy of Formation

[Angelica Nava-1E]

When is it best to use the bond enthalpy method over the enthalpy of formation method and could I use Hess's Method, Bond Enthalpy Method, and Enthalpy of Formation for every problem the asks for the reaction enthaply or do some have restrictions?

[Jenna_Hakel_2A]

I think it all depends on what information is given to you. In the course reader, for example, it begins each new section by saying something along the lines of "When bond enthalpies are not available, use the standard enthalpies of formation." So although all three methods may produce the same answer, it can be difficult to always use Hess's method if there are not reaction enthalpies easily available for all of the steps. And the same goes for the other methods. So, overall, I would say that any method can be used, but I think that in general the information presented in the problem will give you a good idea of which method should be used. :) Hope that helped!