<P> Diffusion is the net movement of molecules or atoms from a region of high concentration (or high chemical potential) to a region of low concentration (or low chemical potential) as a result of random motion of the molecules or atoms . Diffusion is driven by a gradient in chemical potential of the diffusing species . </P> <P> A gradient is the change in the value of a quantity e.g. concentration, pressure, or temperature with the change in another variable, usually distance . A change in concentration over a distance is called a concentration gradient, a change in pressure over a distance is called a pressure gradient, and a change in temperature over a distance is called a temperature gradient . </P>

What are all types of diffusion dependent on