Enthalpy of N2H4 gas decomposition using bond energies

[lizgore94]

I am trying to determine the change of heat for:

N2H4(g) -> N2(g) + 2H2(g)

Here is what I did and what I got the correct answer is -86.0 which I am clearly not getting

[(163)+ (2*436)] - [(4*391) + (163)] = -692

thanks for any help!

 

[sjb-2812]

Where have all these numbers come from?