1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Heat of combustion help

  1. Jul 3, 2005 #1
    Determine the heat of combustion of methane (CH4(g)) by writing a balanced equasion and using the bond energies indicated below.

    C--H = 414 KJ/mol
    O==O = 502 KJ/mol
    C==O = 799 KJ/mol
    O--H = 464 KJ/mol

    I've googled it and apparently the answer is -890 KJ/mol but when I calculate it it gives me -794 KJ/mol. I must be doing something wrong :S
  2. jcsd
  3. Jul 4, 2005 #2


    User Avatar
    Homework Helper
    Gold Member

    I'm getting -794 KJ/mol as well. You googled the experimental value of the Heat of Combustion of methane? Maybe the difference is because the bond energies used are not fully accurate.
  4. Jul 4, 2005 #3
    [tex] CH_4 + 2O_2 -> CO_2 + 2H_2O[/tex]
    change in energy content = [tex]2*799 + 2*2*464 - (4*414 + 2*502) = -794KJ/mol[/tex]
    :rofl: same
    any1 to point out what's wrong?
  5. Jul 4, 2005 #4
    well, your bond energies also do not agree.
    see red corrections below:
    check below for details:
    http://members.nuvox.net/~on.jwclymer/rq/hoctable.html [Broken]
    Last edited by a moderator: May 2, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Heat of combustion help