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He atoms move faster than all of the Ne atoms

  1. Aug 11, 2005 #1
    In a mixture of Ne and He at equilibrium, all of the He atoms move faster than all of the Ne atoms.

    Why is this false?

    Shouldn't it be true, since Ne atom is heavier than He atom. Thanks for any help
  2. jcsd
  3. Aug 11, 2005 #2


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    Well maybe the problem is with the term "all". Sure, on average the He atoms are faster, but given the very chaotic nature of the mixture, it is very possible, that at a given instant, one or more atom of Ne goes faster than any of the He atoms.
  4. Aug 11, 2005 #3


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    The molecules of a gas move in all possible speeds in all possible directions. Thus the gas contains molecules with very low velocities to very high velocities (Maxwell's distribution). When we think of the relation between temperature and velocity (or KE) this is rms velocity of the molecules
  5. Aug 11, 2005 #4

    This has to do with chemical kinetics,
    Thnk of what happens when you put a hot object against a cold object. Heat transfers into the colder object until an equilibrium is achieved.

    Its basically the same thing.
    Atoms with higher kinetic energy (faster movement,) will distribute energy to atoms with lower kinetic energy in the same system, until an equilibrium of kinetic energy is achieved.
    Ie, the faster moving atoms will collide with slower moving atoms, transferring some of the kinetic energy, untill each atom in the system has the same amount of kinetic energy.

    This action is spontanious.
  6. Aug 11, 2005 #5
    Ahh, I see, thank you very much for your help guys.
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