Transport processes in compressed liquid pyridine

Abstract

The self-diffusion coefficients of liquid pyridine have been measured as a function of temperature and pressure over the density range 2.7⩽ρ/ρc⩽3.7 and the temperature range 0.5⩽T/Tc⩽0.7 using the NMR spin–echo technique. The shear viscosities and densities have also been measured under the same experimental conditions. The experimental diffusion and viscosity data are interpreted in terms of the rough hard sphere (RHS) model of liquids and the RHS parameters calculated are compared to those obtained for liquid benzene, a molecule of nearly identical shape and size but lacking the dipole moment of pyridine and its specific intermolecular interactions. A qualitative discussion of the experimental results is presented. The Stokes–Einstein relationship between D and η is found not valid for liquid pyridine.