Thermo-Acoustic Properties of Propiophenone with Alkyl (C3–C5) Ethanoate at Different Temperatures, T = 303.15, 308.15, and 313.15 K

Densities (ρ) and sound velocities (u) were experimentally measured for the liquid mixtures of propiophenone (PP) + (C₃–C₅) alkyl ethanoate (/alkyl acetate) over the whole composition range at temperatures of 303.15, 308.15, and 313.15 K. Acoustic impedance, Z, isentropic compressibility, β_s, and intermolecular free length, L_f, were calculated from experimental values of ρ and u, and their corresponding excess properties, i.e. excess molar volume V^E, deviations in the speed of sound, Δu, acoustic impedance, ΔZ, isentropic compressibility, Δβ_s, and intermolecular free length, ΔL_f, were calculated and fitted with the Redlich–Kister equation. The type of interaction occurring between components in these binary mixtures were discussed based on these deviation/excess properties as functions of temperature (T) and composition (X₁). In addition, ρ and u data were correlated with the Jouyban–Acree model, and their interaction constants, along with their standard deviations, were also calculated. Furthermore, central composite design (CCD) based response surface methodology (RSM) was employed to develop predictive model equations for the thermodynamic properties. The observed strong interactions between unlike molecules were attributed to interstitial accommodation and dipole–dipole interactions within liquid mixtures.