[yoyoils]

my textbook is telling me

(sum of strengths of bonds broken) - (sum of strengths of bonds formed) = Ho

so naturally I look up bond strength charts to find there's just bond dissociation and bond energies if I'm correct. It's kinda hard to find out which I should be using but here's the practice problem.


CH4 + 2 O2 ----> CO2 + 2 H2O(liq) answer is -213kcal mol-1

except somehow I'm getting -198kcal mol

I got my answer trying to use http://www.cem.msu.edu/~reusch/OrgPage/bndenrgy.htm

[Zeppos10]

as a product of the reaction, use water in its gaseous state: the bonds between the water molecules in the liquid phase are not included in the table.