Chemical diffusion derivation from thermodynamic factor and self-diffusion


by DiffusConfuse
Tags: chemical, derivation, diffusion, factor, selfdiffusion, thermodynamic
DiffusConfuse
DiffusConfuse is offline
#1
Apr16-12, 01:18 AM
P: 6
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.

AB2 metal.

Overall diffusion D= XADB+XBDA

meaning the chemical diffusion of B is:

DCB=XADB=XADTB(1+∂lnγ/dlnXB)

and the chemical potential of B is:

μA00.5B2+RTlnγBxB00.5B2+RTlnp0.5B2

finally the mole fractions of XB and XA vary accordingly:

XB = (2+x)/(3+x)

XA = 1/(3+x)

and then DCB is:

DCB=DTB(2+x/2) ∂ln(pB2)/dx

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!
Phys.Org News Partner Physics news on Phys.org
Better thermal-imaging lens from waste sulfur
Scientists observe quantum superconductor-metal transition and superconducting glass
New technique detects microscopic diabetes-related eye damage

Register to reply

Related Discussions
diffusion coefficient in diffusion equation and random walk ? Atomic, Solid State, Comp. Physics 3
Diffusion equation and neutron diffusion theory Nuclear Engineering 15
Gas Diffusion? Biology, Chemistry & Other Homework 4
Diffusion equation (derivation) Calculus & Beyond Homework 2
Diffusion of H2 into Air. Classical Physics 0