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Homework Help: Please help - chemical bonding and energy change

  1. Oct 30, 2006 #1
    I am not positive if I did this correctly, but I was wondering if someone could check and then, potentially, offer ideas.

    The question asked to use bond energies and estimate the energy change deltaH (in kJ/mol) for

    N=N + 2H2 --> H2N-NH2

    (that first N=N is triple)

    I think I just realized I did this wrong, because I didn't use a triple for the first one, but I'll write down what I did anyway, and maybe someone can help.

    N=N = 418 kJ
    H2 = 872.8 kJ
    total = 1290.8 kJ

    Then, I did
    4 H2 bonds = 4x436.4 = -1745.6
    2 N-H bonds = 2 x 393 = -786
    total = -2531.6

    Therefore, 1290.8 + (-2531.6) = -1240.8 kJ/mol

    sheesh... Please?
  2. jcsd
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