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Actual Distance Between Atoms of an Ideal Gas

  1. Sep 19, 2004 #1
    Hi, I am working on a project in which I need to know the distance between the particles in an ideal gas system. I have tried searching (google) for it but was unable to come with any actual values, just general terms. Can anyone refer me to where I might find this? Thanks
  2. jcsd
  3. Sep 19, 2004 #2


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    1 mole of a gas has ~ 10^24 molecules and occupies about 22 liters (or 22 dm^3) at STP. So, the average spacing between molecules is roughly the cube root of 22*10^-24 dm ~ 3*10^-8 dm = 3*10^-9 m or about 30 angstroms or 3 nm.

    Note : This distance is a function of temperature. Use the Ideal Gas Law to figure out for other P,T values.

    The mean free path calculator here also gives average intermolecular spacing.

    I know that Nitrogen deviates little from ideality over a fair range of temperatures and pressures...so here goes (now using this calculator, to double check):

    At 760mm Hg, 273 K and molecular diameter of 2.0 A (2.0 * 10^-10 m), which is the diameter of a N2 molecule, the calculator gives 3.3 nm...close enough to my guess. :smile:
    Last edited: Sep 19, 2004
  4. Sep 19, 2004 #3
    Thank you!
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