The spontaneous movement of energy or matter from a region of high concentration to a region of lower concentration that continues until a uniform mixture is obtained. Diffusion occurs from the random movement of molecules and thus happens fastest in gases, more slowly in liquids and slowest in solids. The rate of diffusion of a gas through a barrier material is a function of the permeability of the material and the concentration of the gas on each side of the barrier. The rate increases with increasing temperature and pressure. Examples of diffusion are: a solid dissolves in a liquid; the mixture of two gases; osmosis in plant and animals cells; the intermixing of molecules in some adjacent metals over long periods of time.
Synonyms and Related Terms
Diffusion (Deut.); diffusion (Fr.);