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Diffusion vs. size

  1. Feb 23, 2009 #1
    1. The problem statement, all variables and given/known data
    23v11kk.jpg
    fctgth.jpg

    Eq. 4.14:

    [tex]
    \zeta = 6 \pi \eta R
    [/tex] (Stokes formula)

    2. The attempt at a solution

    In my plot, collagen, hemoglobin and lactoglobulin give a straight line, while ribonuclease is a bit above the others.

    I don't know which diffusion law I'm supposed to use. Fick's? Anyway, here's what I've done:

    [tex]
    \zeta = 6 \pi \eta R
    [/tex]

    [tex]
    \eta = 10^-3 kgm^{-1}s^{-1}
    [/tex]

    [tex]
    k_BT = 4.1E-21 J
    [/tex]

    [tex]
    \zeta D = k_BT \Rightarrow D = \frac{k_BT}{\zeta} = \frac{k_BT}{6\pi \eta}\cdot\frac{1}{R} \Rightarrow D = 2.2E-19 \cdot \frac{1}{R}
    [/tex]

    Am I on the right track? I'm not sure what the problem asks me to do, really...
     
    Last edited: Feb 23, 2009
  2. jcsd
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