Question

Define binary diffusion and self-diffusion. Give typical orders of magnitude of diffusivities for gases, liquids, and solids

Answer 1

Solution :

Binary diffusion from ficks law relates the diffusive flux to the concentration under the assumption of steady state. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low concentration across a concentration .

self-diffusion self-diffusion is the diffusion coefficient of species when the chemical potential gradient equals zero. It is the random translational motion of molecules and ions driven by internal kinetic .

Diffusivity of gases is of order = 10^-5 m2/s

Diffusivity of solid is of order = 10^-3 m2/s

Diffusivity of liquid is of order = 10^-9 m2/s

Wish you all the best buddy please upvote it ?