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Heat of reaction

  1. Apr 24, 2006 #1
    53. For the reaction

    CO + NO2 ---> CO2 + NO

    The activation energy for the forward reaction is 135 KJ/mol of CO reacted.

    a) Determine the heat of reaction.

    DH = Hf products - Hf reactants

    = (197.9 + 240.5) - (213.6 + 210.6)

    = 14.2 kJ/mol

    b) From the data given, and the DHr for the reaction, determine the activation energy for the reverse reaction.

    Im pretty sure I did part a right, but how do I do part b?
  2. jcsd
  3. Apr 24, 2006 #2


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    Try thinking of the reaction graphically. Have you seen a graph of a chemical reaction, Energy vs. Time? Try drawing it out, and determine what the activation energy for the forward rxn and the heat of reaction represent graphically. Then figure out what the activation energy for the reverse reaction would look like, and see if you can then figure it out from the other values.
  4. Apr 25, 2006 #3
    Yes I have seen and read about activation energy, and the only thing I could think of for this problem is that the activation of the forward reaction is given as 135 kJ/mol.

    135 kJ/mol + 14.2 kJ/mol

    = 149.2 kJ/mol

    So the activation energy for the reverse reaction would be 149.2 kJ/mol?
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