Insights into Molecular Interactions in Binary and Ternary Mixtures of Propan-1-ol, Pyridine, and Benzene: An Experimental and Modeling Approach

Experimental densities and sound speeds at temperatures (293.15, 298.15, 303.15, 313.15, and 323.15 K) and refractive indices at 298.15 K under ambient pressure are reported for the first time for the ternary system {propan-1-ol + pyridine + benzene}, covering the full composition range. Corresponding binary subsystems were also investigated. The excess molar volume, excess isentropic compressibility, and excess refractive index, derived from experimental data, were correlated by using the Redlich−Kister and Cibulka equations for binary and ternary systems, respectively. The composition and temperature dependence of these properties provided insights into molecular interactions and structural effects within the mixtures. The perturbed chain statistical associating fluid theory equation of state modeled the densities of binary and ternary mixtures using a predictive approach. Schaaff’s collision factor theory and Nomoto’s relation modeled sound speeds, while Lorentz−Lorenz, Gladstone−Dale, Laplace, and Eykman mixing rules predicted refractive indices. The Jouyban−Acree model represents the composition and temperature dependence of the thermophysical properties. Ternary excess properties were compared with values predicted by binary contribution symmetric (Kohler and Muggianu) and asymmetric (Hillert and Toop) geometric models. Model accuracy was evaluated using statistical indicators, highlighting the suitability of theoretical and empirical approaches for describing the thermophysical properties in these mixtures.