Diffusion Coefficients of the Systems CO–CO and CO–N2

Abstract

Self‐diffusion and mutual diffusion coefficients in the range 195° to 373°K have been measured for the isostere systems, CO–CO and CO–N2. The self‐diffusion coefficients are consistently higher than the mutual diffusion coefficients, with differences two‐ to fourfold greater than the experimental error. On the assumption that the classical Chapman—Enskog transport relations are applicable, parameters have been obtained for intermolecular potentials of the Lennard‐Jones (12–6) and the exp‐six types. Parameters derived from diffusionmeasurements have been compared with those obtained from measurements of viscosity, compressibility and crystal properties. It was not possible, for either system, to reproduce both the transport and equilibrium properties with a single set of parameters. It is concluded that the failure may be attributed mainly to the use of average spherically symmetric potentials instead of potentials which are functions of both relative molecular orientation and internuclear separation.