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View Full Version : Diffusion vs. size


superwolf
Feb23-09, 06:06 PM
1. The problem statement, all variables and given/known data
http://i41.tinypic.com/23v11kk.jpg
http://i39.tinypic.com/fctgth.jpg

Eq. 4.14:


\zeta = 6 \pi \eta R
(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:


\zeta = 6 \pi \eta R



\eta = 10^-3 kgm^{-1}s^{-1}



k_BT = 4.1E-21 J



\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}


Am I on the right track? I'm not sure what the problem asks me to do, really...