Transport properties of nonelectrolyte liquid mixtures—II. Viscosity coefficients for the n-hexane + n-hexadecane system at temperatures from 25 to 100‡C at pressures up to the freezing pressure or 500 MPa

Abstract

Viscosity coefficients measured with an estimated accuracy of 2% using a self-centering falling body viscometer are reported for n-hexane, n-hexadecane, and four binary mixtures at 25, 50, 75, and 100‡C at pressures up to the freezing pressure or 500 MPa. The data for a given composition at different temperatures and pressures are very satisfactorily correlated by a plot of Ή, defined as 104ηV2/3/(MT)1/2 in the cgs system of units, or generally, 9.118×107η V2/3/(MRT)1/2, versus log V′, as suggested by the hard-sphere theories, where V′ = V · V0(TR)/V0(T) and V0 represents the close-packed volume at temperature T and reference temperature TR. The experimental results for all compositions are fitted, generally well within the estimated uncertainty, by the equation $$\ln \eta ' = {\text{ - 1}}{\text{.0 + }}\frac{{BV_0 }}{{V - V_0 }}$$ (1) where B and V0 are temperature and composition dependent. Values of B and V0 for the mixtures are simply related to values for the pure liquids, and viscosity coefficients calculated on the basis of this equation have an estimated accuracy of 3%. The effectiveness of the recently recommended empirical Grunberg and Nissan equation is investigated. It is found that the parameter G is pressure dependent, as well as composition dependent, but is practically temperature independent.