Apr16-12, 01:18 AM
I am working through a paper in which the chemical diffusion coefficient is related to the self-diffusion (or tracer) through the following derivation, on which I am a little hung up.
Overall diffusion D= XADB+XBDA
meaning the chemical diffusion of B is:
and the chemical potential of B is:
finally the mole fractions of XB and XA vary accordingly:
XB = (2+x)/(3+x)
XA = 1/(3+x)
and then DCB is:
I am confused as to where the (2+x)/2 term comes from.
I believe it is from the mole fraction XA in the overall diffusion equation combined with a derivation including the mole fraction XB from the chemical potential, but can't work it out exactly.
Thank you in advance for any clarification on this topic!
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