Physicochemical Investigation of Intermolecular Interactions Utilizing Ultrasonic and Viscometric Techniques in Binary Liquid Mixtures

Thermophysical properties of binary liquid mixtures comprising isopropyl benzene (cumene) paired with toluene, ethyl benzene, n-propyl benzene, mesitylene, tert-butyl benzene, and biphenyl were experimentally determined at 298.15 K and standard atmospheric pressure. The measured properties included density (ρ), viscosity (η), sound velocity (u), and refractive index (n), this provides valuable insight into the interactions within the mixtures and aids in predicting the behaviour of the chemical systems. In this study, the physical properties of isopropyl benzene (cumene) an important industrial chemical were measured at 298.15 K in binary mixtures with toluene, ethyl benzene, <i>n</i>-propyl benzene, mesitylene, tert-butyl benzene, and biphenyl. Using these experimental data, derived parameters including adiabatic compressibility (<i>β<sub>ad</sub></i>), free volume (V<sub>f</sub>), internal pressure (p<sub>i</sub>), surface tension (<I>S</I>), acoustic impedance (Z), and enthalpy (H) were evaluated as a function of composition to characterize the molecular interplay within the mixtures. The computed excess thermodynamic properties were utilized to construct novel empirical models. While these proposed models require a greater number of coefficients, they provide a substantially improved fit, yielding significantly lower standard deviations compared to traditional Redlich-Kister polynomial equations. Analysis of the mixtures revealed positive deviations for excess acoustic impedance (Z<SUP>E</SUP>), excess surface tension (S<SUP>E</SUP>), and excess enthalpy (H<SUP>E</SUP>). The results indicated the presence of weak interactions between isopropyl benzene (cumene) and aromatic hydrocarbon molecules, Collectively, these compositional trends suggest the presence of weak to moderate intermolecular forces, driven predominantly by solute-solvent interactions and π-π stacking.