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Homework Help: Passive transport

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


    2. The attempt at a solution

    a) The particle seems to be 50 nm in diameter, so

    D = \frac{k_BT}{6 \pi \eta R} = 4.4E-12 m^2s^{-1}


    j_{diff}=-D\frac{dc}{dx} = -4.4E-12 \cdot \frac{dc}{dx}

    I don't know what to do next...Can I assume [tex]c(x) = c_0x[/tex]? In that case,

    j_{diff} = -4.4E-12 c_0

    Is this correct? What are the units?

    And how to do c)?
    Last edited: Feb 23, 2009
  2. jcsd
  3. Feb 23, 2009 #2


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    What does the continuity equation tell you about the flux in the tube? Hint: Fick's Second Law
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