Topics - Diffusivity
The diffusivity of a solute defines the rate of transfer of the solute in a given fluid under the driving force of a concentration gradient. The mass transfer process is called diffusion. Diffusivity is classically defined as the mass of solute transferred per unit area per unit time under unit concentration gradient. In general, the diffusivity of a solute decreases with its molecular weight, and the molecular weight of the fluid through which it is diffusing, increases with temperature, but decreases with pressure. Diffusion is the method of by which the solutes are transported through the individual phases in chromatography systems but transport through the chromatography column results from fluid flow.