โ Scribed by J.C.R. Turner
No coin nor oath required. For personal study only.
The diffusion of a component in a binary isothermal mixture can be regarded as arising either from its concentration gradient or from the gradient of its chemical potential. The 'kinetic' and the 'thermodynamic' approach can both be related to the simple, measurable, mutual diffusion coefficient II,,,. When considering the concentration dependence of 0, the 'thermodynamic' approach leads naturally to the presence of the term (d In a,/d In ni), while the 'kinetic' approach does not. In systems showing marked non-ideality, of which two examples are discussed, allowance for this term greatly simplifies the concentration dependence of D,. This lends support to the proposition that the gradient of chemical potential should be regarded as the 'natural force for diffusion'. In ideal systems it does not matter which approach is used, but where non-ideality is marked, the 'thermodynamic' approach would appear to have advantage.
๐ SIMILAR VOLUMES
Deport~rrcm ofP/fj tical md I~ro~wrrrc Chemistry Um ernt\_v of .-ldelaide -ldelarde. Sour/r Austrah 5001 Rccclrcd I Novcmbcr 198 1. m tin31 form II January 1982 Calcularions of rhe iirst density corrccnon IO the binary dlfiuslon coeificlrnt arc prcsrnted ior sewal matures. These calculanons arc bacd