The coefficient of viscosity of atomic hydrogen and the coefficient of mutual diffusion for atomic and molecular hydrogen

Abstract

The coefficients of viscosity of mixtures of atomic and molecular hydrogen have been determined at about - 80, 0 and 100 $^\circ$C by comparing the pressure differences and mean pressures in a $\mathbf{\cup}$-tube through which is pumped molecular hydrogen and then the mixture at the same mass rate of flow. The compositions of the mixtures are measured at the ends of the tube by means of Wrede gauges. The flow of the mixture through the tube is discussed in some detail. The coefficients of viscosity of atomic hydrogen are derived from the mixture coefficients on the bases of Lennard-Jones (12:6) and modified Buckingham (exp: 6) fits to the H-H$_2$ interaction potentials. The results are in good agreement with the best theoretical values available. Hence, as an alternative procedure, the coefficients of mutual diffusion for H-H$_2$ are derived on the bases of the aforementioned fits and theoretical values.