Chemistry
posted by Kat .
OF2(g) + H2O(g) > O2(g) +2HF(g) ΔH°rxn = 318 kJ
Using bond energies, calculate the bond dissociation energy of the OF bond, in OF2.
This is the question and I got 438 as the answer, which is wrong. I don't know what I did wrong??

If you will post your work I'll try to find the error. I found numbers in my book and you might check what you used. If I didn't skip a line, I read
O=O = 498
OH = 464
HF = 569
Your numbers may differ since we aren't using the same text (I sure of that) but they should be close. 
So I have
O=O = 498
OH = 436
HF = 565
318 = (x+436)  (498+565)
Since reaction=brokenmade
318 = x+436  1063
745 = x + 436
x= 309
Isn't this what you are supposed to do? :(