[dachsienutt]

How do I find the number of Kcal energy released per mole of C8 H18 combusted?

[Mppl]

I think you write the reaction equation go look for the standard entalpies of formation of the products sum it the sum the standard entalpies of formation of the reagentes, then just do (entalpies of formation of the products)-(entalpies of formation of the reagentes) and here you have it, I dont know if you are familiar with that but I think thats the way of doing it
Other way to do it is to search for a equation of that reaction that has the change of entalpy associated to that reaction then just convert it to kcal if it is not in kcal already