PARTIAL MOLAR VOLUMES AND ISENTROPIC COMPRESSIBILITIES OF MIXTURES OFGAMMA-BUTYROLACTAM (N=5) WITH HIGHER ALKANOLS

Ultrasonic speed, u, and excess volume, V-E, measurements have been ma de for mixtures of pyrrolidin-2-one + n-alkanol(C-6-C-10) over the ent ire composition range at 303.15 K. V-E values are negative for pyrroli din-2-one + hexanol, S-shaped for heptanol and completely positive for rest of the mixtures and increase in the order hexanol < heptanol < o ctanol < nonanol < decanol. The V-E results have been used to calculat e the excess partial molar volumes of the components and have also bee n analysed using Prigogine-Flory-Patterson theory which divides V-E in to three contributions viz. the interactional, free volume and P effe cts. It has been found that the dominant role is played by the interac tional term which is the main parameter for deciding the sign and magn itude of excess volumes for pyrrolidin-2-one + alkanol (C-6-C-10) mixt ures. The estimates of the isentropic compressibilities k(s) and of it s excess counterpart, k(s)(E) have been computed from density values ( calculated from excess volumes) in combination with ultrasonic speed d ata. The magnitude of k(s)(E) values are negative for all the systems over the complete mole fraction range and increase in the order hexano l < heptanol < octanol < nonanol < decanol. The apparent molar isentro pic compressibilities phi(k,s) have been derived and its Limiting valu e <(K)over bar (0)> at an infinite dilution has been estimated.