Densities, Refractive Indices, and Derived Properties of Binary Mixtures of Ethanol with Benzene and Pyridine at Various Temperatures Under Atmospheric Pressure

Experimental densities at (293.15, 298.15, 303.15, 308.15, and 313.15) K and refractive indices at 298.15 K are reported for the binary liquid mixtures of ethanol with benzene and pyridine over the entire range of compositions and atmospheric pressure. From these experimental data, the excess molar volumes V-E and deviations in molar refractivity Delta R were derived and fitted by the Redlich-Kister polynomial to determine the adjustable fitting parameters and the standard deviations. The number of adjustable parameters to be included in a Redlich-Kister polynomial for fitting the derived properties was optimized with the F-test. V-E values are found to be negative over the entire composition range in ethanol + pyridine mixtures, without considerable changes over the temperature range studied. In the ethanol + benzene mixtures, the V-E results show an S-shaped composition dependence, and the temperature contribution was found to be very important. The variation of V-E with composition and temperature has been interpreted in terms of molecular interactions between the components of the mixture and structural effects. Delta R values are found to be negative for both mixtures with a minimum located between 0.45 and 0.5 volume fractions of ethanol. Furthermore, several theoretical and empirical mixing rules were applied to predict refractive indices of mixtures in order to test their validity for the present systems.