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Homework Help: Chemistry Homework: Calculate Enthalpy Change

  1. Apr 12, 2010 #1
    1. Calculate the approximate enthalpy change for the combustion of methane:
    CH4 + 2O2 ---> 2H20 + CO2

    2. Relevant equations

    CH4 + 2O2 ---> 2H20 + CO2

    enthalpy= D(reactants) - D(products)

    D= bond dissociation energies

    Bond Dissociation energy (KJ/MOL)

    C-C 350
    C=C 611
    C-H 410
    C-O 350
    C=O 732
    O-O 180
    O=O 498
    H-O 460

    3. The attempt at a solution

    ENTHALPY= D(reactants)-D(products)
    [1640+(2*498)]-[(2*920)-1464]= -668 kJ
     
    Last edited: Apr 12, 2010
  2. jcsd
  3. Apr 13, 2010 #2

    Borek

    User Avatar

    Staff: Mentor

    Why [(2*920)-1464]?

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