Bond Enthalpies

[Carolina Gura Dis 1B]

Are there any bond enthalpies that we should memorize? Also is there a way to find standard enthalpies of formation from an enthalpy of formation that is not standard? For example can you use different non-standard enthalpies of formation for this same bond and find their average to find the actual standard enthalpy of formation for that bond?

[Chem_Mod]

Hi!

You do not have to memorize the values.

For your second question, the definition of standard reaction enthalpy from your book is: "is the standard reaction enthalpy per mole of formula units for the formation of a substance from its elements in their most stable form". Therefore we can only calculate it from the values of the most stable form of the elements that form the substance.