Isentropic Compressibility Studies of Some Salts in Acetonitrile plus N,N-Dimethylacetamide Mixtures at 298 K

Ultrasonic velocities and densities of some copper(l) and silver(I) salts have been measured in the concentration range 0.002-0.28 mol kg(-1) in binary mixtures of acetonitrile (AN) + N,N-dimethylacetamide (DMA) containing 100, 80, 60, 40, 20 and 0 mol % AN at 298 K. The isentropic compressibility (K(s)) and apparent molal isentropic compressibility in various solvent systems have been calculated by using ultrasonic velocity (u) and partial molal volume (V(phi)) respectively. Limiting apparent molal isentropic compressibilities (K(s,phi)(0)) for various salts have been evaluated from vs. m(1/2) plots and split into the contributions of individual ions (K(s,phi)(0))(+/-). The (K(s,phi)(0))(+/-) values for copper(I) and silver(I) ions are found to be negative over the entire composition range which indicate strong solvation of these complex ions. The (K(s,phi)(0))(+/-), values for these ions increase with increase in DMA composition shows that the extent of solvation increases with increase in DMA composition.