Thermo-Acoustic Analysis of Potassium Dichromate in Aqueous 5% dimethyl sulfoxide at Different Temperatures

• Ultrasonic study at 1 MHz over 293.15–313.15K • Wide molality range of a multicharged electrolyte • Evaluation of thermo-acoustical parameters. • Clear separation of molality- and temperature-driven effects Density (ρ), speed of ultrasonic wave (U), and viscosity (η) values were determined in potassium dichromate solutions at molalities of 1.5, 2.7, 3.5, 4.2, 5.6, 6.5, and 7.2 m in an aqueous solvent mixed with 5% v/v dimethyl sulfoxide (DMSO). Temperature varied in the 293.15K -313.15K interval in 5K steps at an ultrasonic frequency of 1 MHz. By using the experimental values of these physical parameters, other values such as adiabatic compressibility (β), intermolecular free length (L f ), acoustic impedance (Z), relaxation time (τ), and Gibbs free energy (ΔG) were determined using the standard equations. Based on the experimental values of these parameters as functions of temperature and molality, it is possible to interpret the influence of temperature on the interaction in potassium dichromate solution in terms of electrostatic interactions between cations and anions produced by electrolyte dissociation that favour the formation of ion pairs in higher molality regions while the role of thermal motion starts dominating in the lower regions.