ABSTRACT
Molecular diffusion is the migration of matter along a concentration gradient from a region of high concentration to a region of low concentration. It is the result of random molecular motion, and it produces spontaneous mixing in inhomogeneous systems. Molecular diffusion controls, to a degree, the transport rate of chemicals at phase boundaries and in the slow-moving fluids found in porous media. To a lesser degree, it controls the dispersion of chemicals in turbulent fluids.
