Diffusion Coefficient - related to Fick's laws of diffusion


Diffusion is the net movement of a substance (e.g., an atom, ion or molecule) from a region of high concentration to a region of low concentration. This is also referred to as the movement of a substance down a concentration gradient. A gradient is the change in the value of a quantity (e.g., concentration, pressure, temperature) with the change in another variable (e.g, distance). For example, 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 a called a temperature gradient.
The diffusion coefficient D is the coefficient in the Fick’s first law.

Related formulas


Ddiffusion coefficient (m2/s)
kBBoltzmann constant
Ttemperature (K)
mmolecule mass (kg)
Ppressure (Pa)
dmolecule diameter (m)