Mean Bond Enthalpies -- Resonance Structures

[205677523]

If we're calculating mean reaction enthalpy of a reaction where a product/reactant has resonance structures, but no resonance structure enthalpy is provided in the table, would we take the average of a single/double bond and use that bond enthalpy to do the calculations?

[Will Harvey 1B]

This is a very interesting question. I don't think that we will ever be given that sort of scenario in this class. I would think that for resonance structures that have equivalent bonds (as in you just change the placement of one double bond) you could just pick one and use it since the total bonds would be the same. Otherwise, you could individually find the enthalpy of reaction for each resonance and then average them. However, this doesn't really take into account if there is a dominant resonance species.