<p>The analysis of molecular interactions has proven useful in helping scientists better understand the physicochemical properties of fluids like liquids and their relationship with respect to their respective solutes and solvent interactions by assessing the temperature and concentration dependence of other acoustical properties. This review article will present an evaluation of previously cited research papers that have been conducted on ultrasonic examinations of a binary mixing system of polyethylene glycol for the purpose of improving our knowledge regarding solvency properties. It will describe and discuss the implications regarding the many different industries that rely on products, systems, and processes dependent upon, or affected by, solute–solvent interactions, such as non-destructive testing, medical diagnostics, and chemical process control. Understanding the behaviour of ultrasonics in liquid-phase mixtures will ultimately facilitate the enhancement of process optimisation and quality control activities across many diverse types of technologies and industries.</p> Graphical abstract <p></p>