Finding heats of reaction with tables of bond energies

Question:    I'm having trouble figuring out the heats of combustion of alcohols.  I have a table of bond energies, but don't know what to do next.


Answer:
Here's how to find the heat of a reaction using a table of bond energies:

The amount of energy produced/used in a reaction is equal to the sum of the energies of the bonds that were broken minus the sum of the energies of the bonds that were formed.  As a result, what you need to do is to draw out Lewis structures for everything in the equation and take a big inventory of all the bonds that were broken from the reagents and new ones that were formed from the products.  When you multiply the types of bonds by the energies and do the calculation above, you should get your answer.



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