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Homework Help: Average kinetic energy

  1. Sep 7, 2008 #1
    A gas contains a mixture of He and Ne.
    The gas is at a temperature of 448 K, with
    0.85 mole of He and 2 mole of Ne.
    Avogadro’s number is 6.02 × 1023 mol−1,
    and Boltzmann’s constant is 1.38×10−23 J/K.
    What is the average kinetic energy per
    molecule of He? Answer in units of J.




    2. KE(bar) = (1/2)mv² = (3/2)kT



    3. The middle equation above gives you the average kinetic energy, but I dont have any velocity. Can someone please guide me with this problem?
     
  2. jcsd
  3. Sep 7, 2008 #2

    Ygggdrasil

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    What's wrong with using KE(bar) = (3/2)kT?
     
  4. Sep 7, 2008 #3
    wow, it was just a matter of typing it in correctly. I can't believe this, because I am doing these online, so I didn't know how to type in very small values like with exponents.
     
  5. Sep 7, 2008 #4
    Ok theres part 2 to this question. It looks so similar to this, but the same method doesnt give me the right answer.

    Part 2: What is the average kinetic energy per
    molecule of Ne?

    Part 3: What is the average total kinetic energy of
    He? Answer in units of J.
     
  6. Sep 7, 2008 #5

    Ygggdrasil

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    For part 3 it sounds like the want average kinetic energy per atom of He * number of atoms of He.
     
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