Ultrasonic Velocity and thermoacoustic parameters for copper(I) nitrates in dimethylsulfoxide with Pyridine as cosolvent at 298 K.

Abstract

To study the ultrasonic velocity and thermoacoustic parameters for copper(I) nitrates in dimethylsulfoxide with Pyridine as cosolvent at 298 K. Ultrasonic velocity variation and related factors provide a plethora of information regarding the acoustic behaviour of solutions. These studies help in understanding various kinds of interactions like: ionic interactions in electrolytic solutions, molecular interactions in liquid-liquid mixtures & solute-solvent interactions. To estimate the density (ρ), ultrasonic velocity (u) of Copper (I) nitrate complexes in the range of concentration 0.02-0.28 m Kg-1 in Dimethylsulfoxide (DMSO), Pyridine (Py) and binary mixtures of DMSO+Py having 0, 20, 40, 60, 80 & 100 mole percentage of Py at 298 K and 1 atmospheric pressure. To determine the isentropic compressibility (κs) and apparent molal isentropic compressibility (κs,ø ) (which is the degree of electrostatic force occurring in solution) of various salts in the binary solvent mixtures using density values and ultrasonic velocities. Using long borosilicate glass tubes, the DSA 5000M from Anton Parr was utilized to measure density and ultrasonic velocity at 298 K operating at frequency of 2MHz. The apparent molal isentropic compressibility (κs,ø) of the electrolytes were divided into the contributions of individual ions (κos,ø)±. As the composition of the cosolvent increases, the (κos,ø)± values for Cu (I) ions fall, i.e. they become more negative in magnitude. The (κos,ø)± value for Bu4N+ , Ph4B- , ClO4- , NO3- are positive but it also decreases as it moves to Py rich regions. Strong structural effects due to interactions between solute-solute and solvent-solvent are indicated by negative (κos,ø)± values. Thus, solvation increases in Pyridine rich regions. Furthermore, thermo acoustic parameters were evaluated from the experimentally measured values. The results were associated in terms of molecular interaction between the solute and the solvent, demonstrating that solutes have the potential to break or make structures with solvents. Experimental measurements of density (ρ), ultrasonic velocities (u) in DMSO+Py at 298 K revealed that κosϕ value for the copper(I) nitrates like [Cu(AN)4]+, [Cu(Phen)2]+ , [Cu(BN)4]+ [Cu(DMPhen)2]+ , [Cu(Bipy)2]+ , [Cu(TU)4]+, and the reference electrolyte decreases (less positive) or become more negative as the mole percentage of co-solvent increases. Negative values of κosϕ values indicate strong structural or solvation effects. The κosϕ values were further split to find the value of individual ions. The (κos,ø)± value for Bu4N+, Ph4B- , ClO4- , NO3- are positive but also show decreasing trend in Py rich regions. Negative (κos,ø)± value indicate the presence of strong structural effects in the solvent mixture on the addition of electrolyte. Results show that solvation increases in Pyridine rich regions. Further correlating acoustic parameters in terms of molecular interactions also favored trends in solvation behaviour of electrolytes. The increase in the value of Z depicts the formation of H bond which results in strong solute-solute interactions. The values of κs and Lf decreases as concentration increased for all the electrolytes, indicating a significant structure-forming tendency of copper(I) electrolytes in Py rich locations. The value of RA also increases as the composition of cosolvent increases indicating stronger solvation behaviour in Py rich region. Lf, τ decreased as concentration increased for all the electrolytes indicating strong interactions between the molecules of electrolytes with solvent in Py rich regions.