Definition and interpretation of an apparent diffusion coefficient in multicomponent systems

Abstract

An expression is derived for the apparent diffusion coefficient (i.e. the observable rate parameter) of one solute (no. 1, say) in a multicomponent mixture. It is shown that this expression can take a simple form if the experimental data are utilized in a suitable way. Often the apparent diffusion coefficient will approximate to the true diffusion coefficient, D₁₁.