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According to [[IUPAC]] definition,<ref>[http://goldbook.iupac.org/S05582.html IUPAC Compendium of Chemical Terminology, 2nd edition]</ref> '''self-diffusion''' coefficient is the [[diffusion]] coefficient <math>D_i^*</math> of species <math>i</math> when the [[chemical potential]] [[gradient]] equals zero. It is linked to the diffusion coefficient <math>D_i</math> by the equation:

<math>D_i^*=D_i\frac{\partial\ln c_i}{\partial\ln a_i}.</math>

Here, <math>a_i</math> is the [[activity (chemistry)|activity]] of the species <math>i</math> in the solution and <math>c_i</math> is the concentration of <math>i</math>. This term is commonly assumed to be equal to the tracer diffusion determined by watching the movement of an [[Isotopic labeling|isotope]] in the material of interest.

== See also ==

* [[Diffusion]]
* [[Molecular diffusion]]

==References==
{{reflist}}

{{DEFAULTSORT:Self-Diffusion}}
[[Category:Diffusion]]


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