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 10⁴ ηV ^2/3/(MT)^1/2 in the cgs system of units, or generally, 9.118×10⁷ η V ^2/3/(MRT)^1/2, versus log V′, as suggested by the hard-sphere theories, where V′ = V · V ₀(T _R)/V ₀(T) and V ₀ represents the close-packed volume at temperature T and reference temperature T _R . 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 V ₀ are temperature and composition dependent. Values of B and V ₀ 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.