DEVIATIONS IN REFRACTIVE INDEX PARAMETERS AND APPLICABILITY OF MIXING RULES IN BINARY MIXTURES OF BENZENE + 1,2-DICHLOROETHANE AT DIFFERENT TEMPERATURES

Abstract

The refractive indices, n _D , of pure benzene and 1,2-dichloroethane (DCE) and those of their binary mixtures have been measured over the whole composition range and at 298.15, 303.15, 308.15, 313.15, and 318.15 K. Using the experimental n _D data, deviations in refractive indices, Δn _D , molar refraction, ΔR _m , reduced free volume, Δ(V/R _m ), and internal pressure, ΔP _int, have been estimated. Parameters of polynomial equations, which represent the composition dependence of physical and derived properties, are gathered. The results are discussed in terms of molecular interactions between the component molecules. Applicability of eight different refractive index mixing rules—Lorentz–Lorenz, Weiner, Gladstone–Dale, Heller, Arago–Biot, Newton, Eykman, and Oster's relation—is tested against the measured results, and good agreement has been obtained. Moreover, molecular radii, r, and average molecular radii (r _mix ) of the liquids and their mixtures have been calculated.

Keywords:

• Binary mixtures
• Free volume
• Internal pressure
• Mixing rules
• Molecular radius
• Refractive indices

Notes

^a Tamura and Murakami, 1984

^b Nath and Dubey, 1980

^c Ali et al., 2004

^d Prasad et al., 2005

^e Reddy and Prabhakar, 1985

^f Oswal et al., 2000

^g Dreisbach, 1955–1957