Molecular interactions of butyric and L(+)-lactic acids in water-soluble potassium benzoate solutions: An acoustic and thermodynamic study

The densities and sound velocities were investigated to study the molecular dynamics between potassium benzoate in water-soluble solutions of butyric and L(+)-lactic acids at (0.000, 0.010, 0.020, 0.030) $\mathrm{mol}\bullet {\mathrm{kg}}^{-1}$, across a temperature from 288.15 K to 318.15 K. Numerous acoustical and volumetric characteristics such as apparent and partial molar parameters, transfer properties, expansibility coefficient, temperature-dependent derivatives, and the thermal expansion coefficient were evaluated from the experimentally attained densities and sound speeds data. The results are estimated by analyzing the nature of molecular interactions within the liquid system with insights derived from the co-sphere overlap approach. The use of Hepler's thermodynamic relation serves as a reliable method for defining the structural role (structure-form or disrupt) of the ternary mixture. Interaction coefficients were computed to characterize the solute as well as solvent interactions in the ternary combinations. The hydration number has been calculated for the liquid systems using compressibility data based on Passynski's equation. The shifts detected in the OH stretching band through FTIR analysis indicate the creation of hydrogen bonds in the investigated systems. These findings have practical applications in several industries, aiding in the growth of stable formulations and improved product performance.