Mohd Tariq

Surface thermodynamic behaviour of binary liquid mixtures of benzene+1,1,2,2-tetrachloroethane at different temperatures: an experimental and theoretical study

Surface tensions, σ, of pure benzene, 1,1,2,2-tetrachloroethane and those of their binary liquid mixtures over the whole composition range at 298.15, 308.15 and 313.15 K have been measured. The experimental σ data have been correlated against temperature and concentration using standard relations. The measured values have been used to calculate various useful thermodynamic parameters, viz., deviation in surface tension, Δσ, surface entropy, S s, and surface enthalpy, H s. The sign and magnitude of these parameters were discussed in terms of molecular interactions between the component molecules of the liquid mixtures. A number of empirical, semi-empirical and statistical models and theories such as Aurebach, Sanchez, Goldsach–Sarvas volume fraction statistics, Brock and Bird relation, Sudgens relation and Flory–Patterson–Rastogi model have been used to compute theoretically the values of surface tension. Moreover, deviation in surface tension, Δσ has also been calculated using HSIS and HSEG theories and found to be qualitatively correct.

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

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 Osters 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.

Volumetric, Viscometric and Refractive Index Behaviors of α-Amino Acids in Aqueous Caffeine Solution at Varying Temperatures

Abstract Measurements of density (ρ), viscosity (η), and refractive index ( n ) were carried out on α-amino acids, DL-alanine (Ala), D-phenylalanine (Phe), and DL-threonine (Thr) (0.01-0.05 mol·L 1 ), in 0.05 mol·L −1 aqueous caffeine solution at 298.15, 303.15, 308.15, and 313.15 K. These measurements have been carried out to evaluate some important parameters, viz., apparent molar volume (ϕ v ), partial molar volume (ϕ 0 v ), transfer volume (ϕ 0 v (tr)), viscosity A and B coefficients of Jones-Dole equation, free energies of activation per mole of solvent (δμ 0# 1 ) and solute (δμ 0# 2 ), enthalpies (δ H * ) and entropies (δ S * ) of activation of viscous flow, variation of B with temperature (Δ B /Δ T )P, and molar refractive index ( R D ). These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.

Prediction of internal pressure of binary liquid mixtures using Flory's statistical theory

Internal pressures of a number of binary liquid mixtures of varying natures of component liquids have been predicted using Florys statistical theory. The predicted values have been compared with the experimentally calculated ones. Good approximation has been observed.