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Shomate coefficients for n-octane

  1. Aug 17, 2015 #1
    Hello! I've been looking for coefficients to use with the Shomate equation for n-octane (C8H18), but I have been unable to find any. The NIST Webbook lists some gas phase thermochemistry data:

    http://webbook.nist.gov/cgi/cbook.cgi?ID=C111659&Mask=1#Thermo-Gas

    but it omits the Shomate coefficients that are present for some other compounds (methane, for example). I could extrapolate enthalpy figures using the Cp data included in the NIST entry, but I'd be at a loss as to what to do about entropy at anything but ATP.

    It could be that one can't model Cp/H/S properly for octane using the Shomate equation, though I'm too ignorant to know whether or not that is the case.

    So, can anyone help clear up this matter for me? Thanks!
     
  2. jcsd
  3. Aug 17, 2015 #2

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    You are probably looking at the price of data; i.e., it's not been measured. You might be able to "kluge" together a set from extrapolation of the pentane and hexane values that are in the tables plus a little "Kentucky windage."
     
  4. Aug 19, 2015 #3
    D'oh! Oh well, thanks for letting me know. I'll do my best with what's available.
     
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