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Homework Help: Assumptions of Kinetic Theory: How big should a cubical element be?

  1. Nov 29, 2015 #1
    1. The problem statement, all variables and given/known data
    Assuming uniform distribution. What must be the size of a cubical element of volume in the container so that the number of particles in each volume element may vary by 0.1% when the gas is as standard conditions. Probable deviation is given by N^(1/2) where N is the number of particles.

    2. Relevant equations
    Deviation: N^(1/2)

    3. The attempt at a solution
    I don't know what N is for standard conditions.

    Ans. 3300Angstroms
     
  2. jcsd
  3. Nov 29, 2015 #2

    mfb

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    Staff: Mentor

    There is no "N for standard conditions".

    The particle number fluctuates by N1/2. At which value of N does this correspond to 0.1% of N?

    Relating this to a volume is a step that comes afterwards.
     
  4. Nov 29, 2015 #3
    But one needs a volume
    So we need 0.001N = N^1/2. Solving N = 1,000,000. But I don't see where to go from here without any more info?
     
  5. Nov 30, 2015 #4

    mfb

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    Staff: Mentor

    Some problems need more than one step. Finding N is the first step, finding the volume is the second.
    Good. Now you can find the volume that has (on average) 1 million particles in it. How many particles are in a mole? What is the volume of a mole at standard conditions?
     
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