Mass Diffusivity

Mass Diffusivity

Diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion). Diffusivity is encountered in Fick's law and numerous other equations of physical chemistry.

It is generally prescribed for a given pair of species. For a multi-component system, it is prescribed for each pair of species in the system.

The higher the diffusivity (of one substance with respect to another), the faster they diffuse into each other.

This coefficient has an SI unit of m2/s (length2 / time). In CGS units it was given in cm2/s.

Read more about Mass Diffusivity:  Temperature Dependence of The Diffusion Coefficient, Pressure Dependence of The Diffusion Coefficient, Effective Diffusivity in Porous Media, Example Values

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