Insight into Solute–Solvent Interactions of Potassium Chromate in 5% Tetrahydrofuran through Ultrasonic Measurements

In this paper, the physiochemical properties of potassium chromate in the presence of 5% THF-water mixture are analyzed through ultrasonics in order to comprehend the interaction behavior between solute and solvent. The ultrasonic velocity (U), density (ρ), and viscosity (η) are measured for frequency 1 MHz and temperatures ranging from 293.15-313.15 K, with molality in the range of 1.5-7.5 mol/kg. Ultrasonic velocity and density show direct dependence on concentration while the viscosity increases steadily. From the analysis of the thermo-acoustic parameters, there is a noticeable increase in free volume from 3.204 to 13.635 × 10⁻³ m³ mol⁻¹ (∼325%), indicating an increased molecular mobility. Internal pressure, on the other hand, decreases from 8.680 to 4.225 N m⁻² (∼51%). Rao’s constant and Wada’s constant also experience increments from 2.306 to 3.940 (∼71%) and 0.231 to 0.390 (∼69%). The variation of molar volume, as a result of changing concentration, ranges between 23.497 to 37.023 (57%) while there is an increment in molar volume when changing with temperature. Available volume ranges between 1.375 to 1.797 (31%) because of changing concentration while decreasing with increasing temperature. This gives insight into the behavior of potassium chromate in structure modifying behavior in the 5% THF-water mixture.