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Homework Help: Heat of formation question.

  1. May 11, 2013 #1
    1. The problem statement, all variables and given/known data
    Using the information provided for energy changes associated with the formation
    of carbon dioxide, calculate the enthalpy for the formation of carbon monoxide.

    C(gr) + O2(g) → CO2(g) ΔH (-393.5 kJ mol-1)
    CO(g) + ½ O2 (g) → CO2 (g) ΔH (-283 kJ mol -1)
    C(gr) + ½ O2 (g) → CO(g) ΔH = ?

    2. Relevant equations
    None really.

    3. The attempt at a solution
    Reverse equation #2 to get CO2 (g) → CO(g) + ½ O2 (g) (+283 kJ mol -1). I think that's one of the steps anyway. Haven't done of these in ages. Do I sub in for CO2 in equation #1 and then add the enthalpy of formations? What's the next step?
  2. jcsd
  3. May 12, 2013 #2


    User Avatar

    Staff: Mentor

    Combine first two equations in such a way they yield third.
  4. May 12, 2013 #3
    Thanks for that.
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