Bond Enthalpies Question #1 Midterm

[704578485]

On question #1 of the midterm my method was to label and list the bonds of the reactants and the bonds of the products and compare the lists to see which bonds were formed/ broken. I then summed the bond enthalpies for the bonds formed and subtracted from it the sum of the bond enthalpies of the bonds broken. I got 1081kj for part 1 and -418kj for part 2 but these are incorrect. What is the process/answer for this problem?

[Chem_Mod]

On question #1 of the midterm my method was to label and list the bonds of the reactants and the bonds of the products and compare the lists to see which bonds were formed/ broken. I then summed the bond enthalpies for the bonds formed and subtracted from it the sum of the bond enthalpies of the bonds broken. I got 1081kj for part 1 and -418kj for part 2 but these are incorrect. What is the process/answer for this problem?

The correct answer for the A part is 7kj/mol and for the B part 45 kj/mol. Actually you should directly identify which bonds were formed/broken. I guess what you did wrong here is you didn't identify all the bond formed/broke correctly. If you still cannot the the correct answer please go to one of the office hour or ask your TA after discussion/lecture.