ULTRASONIC VELOCITIES AND ISENTROPIC COMPRESSIBILITIES OF SOME TETRAALKYLAMMONIUM AND COPPER(I) SALTS IN ACETONITRILE AND BENZONITRILE

Ultrasonic velocities and densities of Bu4NBPh4, Pr4NBPh4, Et4NBPh4, B U4NClO4, Pr4NClO4, Et4NClO4, Bu4Nl, CUClO4 . 4CH3CN and [Cu(DMPhen)2]C lO4 in acetonitrile and benzonitile have been measured at 298, 308 and 318 K. The isentropic compressibilities (kappa(S)) and apparent molal compressibilities (kappa(phi)) of various electrolytes have been eval uated. The limiting apparent molal compressibilities (kappa(phi)O) for all electrolytes have been obtained by extrapolation of the plots of kappa(phi) vs. square root of molality (m1/2) and split into limiting ionic compressibilities (kappa(phi+/-)O. Kappa(phi+/-)O is positive in benzonitrile except for Et4N+ and is negative in acetonitrile except for BU4N+, Ph4B-and Pr4N+. The results indicate stronger solvation of ions in acetonitrile than in benzonitrile.