Diffusion Coefficient for two different gases (related to Fick's laws)


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. For two different gases, with different molecular masses and molecular diameters , the mean free path estimate of the diffusion coefficient:The diffusion coefficient “D” is the coefficient in the Fick’s first law and is related to the molecular masses, the molecular diameters and the conditions of pressure and temperatures (same for both gases).

Related formulas


DDiffusion coefficient (m2/s)
kBBoltzmann constant
mAMolecule mass of one of the two gases (kg)
mBMolecule mass of the other gas (kg)
TAbsolute temperature (K)
PPressure (Pa)
dAMolecule diameter of one of the two gases (m)
dBMolecule diameter of the other gas (m)