Transport and Equilibrium Properties of Polar Gases

A simple preaveraged 12–6–6 potential model has been used to explain the observed viscosity and diffusion coefficients of polar gases. Force parameters for several polar gases have been determined from the experimental values of viscosity at different temperatures and observed dipole moments. Experimental second virial coefficient data in conjunction with the force parameters determined from viscosity have been used to estimate the molecular quadrupole moments. The results for three polar molecules (NH3, SO2, and CH3OH) have been reported. It has been shown that while the transport properties of a polar gas can be adequately described by a potential function consisting of a L-J (12–6) part plus a contribution due to the dipole moment, the contribution of the higher multipoles to the second virial coefficient of the same gas is not negligible.