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What is fugacity?

  1. Apr 25, 2014 #1
    What is fugacity ? I know it the corrected pressure for non ideal systems , but I need a much more intuitive sense of the term. It would be nice to get some help on this...
  2. jcsd
  3. Apr 25, 2014 #2

    Simon Bridge

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    The intuitive sense for it is "pressure" - a pressing in against a surface.
    It's basically a way to convert ideal gas equations into equations more useful for real gasses.
  4. Apr 26, 2014 #3
    For an ideal gas, VdP = RT d lnP

    For a real gas, we use an equation of the same form to express VdP:

    VdP = RT d ln f

    where f is the fugacity. This is used to determine the change in Gibbs free energy dG = VdP at constant temperature. So dG = RT d ln f. In practice, it is easier to work in terms of the fugacity than the pressure when working in the non-ideal gas region.

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