Self‐diffusion measurements in methane by pulsed nuclear magnetic resonance

Abstract

Abstract The self‐diffusion coefficient of methane has been measured from 150° to 350°K. and from 200 to 5,000 lb./sq. in. abs. At constant temperature, the density‐diffusivity product is constant up to neighborhood of critical density and decreases sharply above that density. The temperature dependence of the low density data agrees with Chapman‐Enskog theory. The Lennard‐Jones (6‐12) parameters determined from the low density data (ϵ/ k = 130°K., σ = 3.85Å.) are in good agreement with those determined by other methods. A correlation for the self diffusion coefficient for methane has been developed which may provide predictions of other spherical nonpolar gases.