Transport, Acoustic, and Thermodynamic Investigation of Nonideal Binary Liquid Mixtures

The viscosity (η) and ultrasonic speed (c) of binary mixtures containing tert-butanol (1) and hydrocarbons (n-hexane, cyclohexane, benzene, ethylbenzene, and cumene) (2) were recorded at temperatures from 298.15 to 318.15 K and at 0.1 MPa pressure. Based on the collected data, deviation in viscosity (Δη), deviation in ultrasonic speed (Δc), excess isentropic compressibility (κSE), and excess Gibbs free energy of activation (ΔG*E) were determined and correlated using the Redlich–Kister equation. TheΔη, ΔG*E, and Δc follow the order: n-hexane > benzene > ethylbenzene > cumene > cyclohexane, while the corresponding values shows an inverse trend. Furthermore, the changes in Δη and κSE were examined using a semiempirical association-based modeling approach. The theoretical estimates aligned well with the experimental findings, and the temperature effect on these properties was systematically calculated. Throughout the whole temperature range, all systems exhibited negative values ofΔη, ΔG*E, and Δc values, indicating that weaker interactions between unlike molecules predominate compared with those in the pure components.