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Homework Help: Hess' Laws

  1. Nov 21, 2005 #1
    Given the following information:
    Fe2O3 + 3CO -> 2Fe + 3CO2 Heat = -28.0 kJ
    3Fe + 4CO2 -> 4 CO + Fe3O4 Heat =-12.5 kJ
    FInd the heat for the following reaction:
    Fe2O3 + CO -> CO2 + Fe3O4
    Balance the equation first and remember to include the correct units.

    3Fe2O3 + CO -> CO2 + 2Fe3O4

    Fe2O3 + 3CO --> 2Fe + 3CO2 H = -28 kJ
    2(3Fe + 4CO2 --> 4CO + Fe3O4 H = -12.5 kJ)

    3(Fe2O3 + 3CO --> 2Fe + 3CO2 H = -28.0 kJ)
    6Fe + 8CO2 --> + 2 Fe3O4 H = -25.0 kJ

    3Fe2O3 + 9CO --> 6Fe + 9CO2 H = -84.0
    6Fe + 8CO2 --> 8CO + 2Fe3O4 H = -25.0 kJ

    Thus, 3Fe2O3 + CO -> CO2 + 2Fe3O4 and H = -109 kJ??


    Use the presented information to find the  H for: N2 + O2 ->2NO
    1/2 N2 + O2 -> NO2 H = 32.16
    4NO + 2O2 ->4NO2 H = -227.9

    1/2 N2 + O2 -> NO2 H = 32.16
    1/2 (4NO + 2O2 ->4NO2 H = -227.9)

    2(1/2 N2 + O2 -> NO2 H = 32.16)
    2NO2 --> 2NO + O2 H = +113.95

    N2 + 2O2 --> 2NO2 H = 64.32
    2NO2 --> 2NO + O2 H = +113.95

    Thus, N2 + O2 ->2NO and H = 178.27 = 178.3 ?? I suppose the units are kJ even if they didn't state which units are used?

    Thanks.
     
  2. jcsd
  3. Nov 22, 2005 #2
    Any volunteers?

    Thanks again.
     
  4. Nov 22, 2005 #3
  5. Nov 23, 2005 #4

    Gokul43201

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    I get the same numbers on both problems. You're doing good.
     
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