Vol. 7, Issue 1, Part B (2025)

The present review aims to explore and analyze the thermodynamic and acoustic behavior of binary liquid mixtures through the study of excess molar volume (Vᴱ), excess molar enthalpy (Hᴱ), and speed of sound. The primary objective is to investigate how molecular interactions, temperature variation, and compositional changes influence these excess properties, which serve as sensitive indicators of non-ideal mixing behavior. Each of the experimental methods classical dilatometry, pycnometry, and current vibrating-tube densimeters offers special benefits in terms of precision, throughput, and operational simplicity. Likewise, Hᴱ values are acquired with high sensitivity calorimetric techniques including flow calorimetry and isothermal microcalorimetry. These approaches enable a strong knowledge of the thermodynamic behaviour of liquid mixes over a large spectrum of situations. Using empirical and semi-empirical equations such as Redlich-Kister, Margules, Wilson, and NRTL theoretical modelling has been performed to match experimental data with standard deviations used to evaluate model dependability. Results across several binary systems showed consistent correlations between Vᴱ, Hᴱ, and speed of sound, therefore exposing the link between volumetric and energetic changes with molecular packing, hydrogen bonding, and structural fit. Whereas positive values indicate weaker, repulsive, or sterically inhibited interactions, negative values of Vᴱ and Hᴱ usually indicate strong specific interactions like hydrogen bonding. Temperature was found to have a major impact on these characteristics, usually reducing favourable interactions and moving surplus features either towards zero or positive values. Understanding molecular interactions depends on excess thermodynamic and acoustic features, so this study emphasises their relevance and provides essential information for solvent selection, formulation design, and process optimisation in chemical and pharmaceutical sectors.