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Homework Help: Question about Calculating Bond Energies

  1. Dec 1, 2017 #1
    1. The problem statement, all variables and given/known data
    Part of a chemical equation, but i had to calculate the bond energies in C2H6,

    2. Relevant equations
    im given that C-H bonds are 414 kj/mol



    3. The attempt at a solution
    and that i know there are 6 of these based on the lewis structure, but how come i don't have to include C-C bond energy? I wasnt given the bond energy for this. C2H6 was part of a chemical equation in which i had to calculate the bond energy for to find change in H
     
  2. jcsd
  3. Dec 1, 2017 #2
    Is it because if the elements are the same, then there is no bond energy? Cause i know that elements have 0 heat of formation
     
  4. Dec 1, 2017 #3

    Borek

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    Staff: Mentor

    Definitely not zero. Can you show whole question, perhaps C-C bond can be somehow ignored?
     
  5. Dec 1, 2017 #4
    Hopefully you can see the question in the pic. It's question 16. Calculate change in H. IMG1227841956.jpg
     
  6. Dec 1, 2017 #5

    Borek

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    Staff: Mentor

    Too small for details, but I still think C-C bond energy cancels out.
     
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