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Kinetic Theory of Gases: Effusion and Collisions

  1. May 2, 2013 #1
    Question:

    In the following link I'm concerned with only pages 1 and 2. I'm wondering if there is a typo or an error of some kind. I feel like there is some inconsistency to what the author refers to as [itex]\upsilon[/itex], [itex]\theta[/itex], and [itex]\phi[/itex]. The only angle shown in the diagram is [itex]\upsilon[/itex], which is the angle the constructed parallelepiped makes with the surface normal.

    For instance, the volume of the parallelepiped involves [itex]\upsilon[/itex] and the # of molecules crossing through dA in time dt involves [itex]\theta[/itex], but then the flux again involves [itex]\upsilon[/itex]. Shouldn't all of those quantities involve only [itex]\upsilon[/itex]?

    http://ocw.mit.edu/courses/chemistr...y-ii-spring-2008/lecture-notes/29_562ln08.pdf

    Hopefully I am wrong. Thanks in advance for any help guys.
     
  2. jcsd
  3. May 2, 2013 #2

    haruspex

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    It's not [itex]\upsilon[/itex], it's a somewhat stylised [itex]\theta[/itex]. Does that resolve it?
     
  4. May 3, 2013 #3
    Wow, I feel horrendously stupid. Sorry for wasting your time, haruspex.
     
  5. May 3, 2013 #4
    However, I did stumble across a legitimate error. The distribution, as well as the average flux, should contain [itex]e^{\frac{-mv^{2}}{2kT}}[/itex]. What is shown is [itex]e^{\frac{-mv^{2}}{kT}}[/itex] - missing the factor of 2 in the dominator of fractional exponent. However, the correct answer is shown for the result of the integral. Still should have that factor of 2 though.
     
  6. May 3, 2013 #5

    haruspex

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    If it allows you to progress, my time was not wasted.:cool:
     
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