The Viscosity of Gases and the Theory of Corresponding States

The viscosity of gases is examined using the theory of corresponding states. The curve of reduced viscosity plotted against reduced temperature is compared with the theoretical curves obtained for several intermolecular potentials. The approximate Sutherland equation gives the best fit and it is suggested that this be used to extrapolate viscosities to high temperatures where experimental data are not available. The reduced viscosity – reduced temperature plot can be used for estimating the viscosities of simple gases from critical data, or critical data from the viscosities.