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Combustion values

  1. Nov 7, 2013 #1
    How do I tell if a certain species will not react or combust with O2 gas regardless of the conditions? I am trying to deduce which species will have standard enthalpy (or entropy or Gibbs' free energy) of combustion of 0, besides obviously O2 itself. e.g. CO2, H2O, perhaps ...?
  2. jcsd
  3. Nov 12, 2013 #2
    You can look up the measured and calculated values in the NASA polynomial table (either the formation or standard enthalpy).
    The tables are maintained by Professor Burcat:

    But this information will not tell you if a species will react or not. N2 has standard enthalpy of combustion 0, but it will still react with combustion products to form NO and NO2 at high temperatures. The reaction will just not have used or released any net energy.
    It's more insightful to look at the activation energy of a certain reaction. This will tell you how much energy (usually by heating) you initially have to give to your mixture to start the reaction A->B The reaction can also occur in the other direction: B->A. The difference in activation energies between these two give you ΔH.
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