Ultrasonic Velocity (U) and Density (ρ) have been measured using Antonpaar’s DMA 5000M in a concentration range of 0.1 – 0.6 M and eleven compositions at 298, 303, 308, 313 and 318K temperatures for a ternary mixture of Aqueous Ethylene Glycol and Copper Sulphate system to study ion- solvent interactions and Eigen-Tomm Ion Pair formation Mechanism (ETIPM). It is observed that the values of density and ultrasonic velocity of any ionic liquid vary with increase in concentration of solutions, mainly due to the change in structure of solvent or solutions as a result of hydrogen bond formation or dissociation or hydrophobic or hydrophilic character of solute, or the solventsolvent interactions, between Ethylene Glycol and water. Adiabatic compressibility (β) data indicate an ordering interaction leading to the formation of an ionic complex. The ionic complex formation in an ionic system is due to ionic association.
