APPARENT MOLAR HEAT-CAPACITIES OF AQUEOUS-SOLUTIONS OF PROPYLAMINE, 1,4-BUTANEDIAMINE, 1,6-HEXANEDIAMINE, PROPYLAMINE HYDROCHLORIDE, PROPIONAMIDE, PYRIDINE, AND SODIUM BENZENESULFONATE AT TEMPERATURES FROM 300K TO 525 K AND A PRESSURE OF 28 MPA

The apparent molar heat capacities of dilute aqueous solutions of prop ylamine, 1,4-butanediamine, 1,6-hexanediamine, propylamine hydrochlori de, propionamide, pyridine, and sodium benzenesulfonate were measured at 300 K < T < 525 K and p = 28 MPa. Corrections for hydrolysis or dis sociation reactions and relaxation effects were applied where necessar y, and the results were extrapolated to infinite dilution to obtain C- p,2(infinity) After subtracting the heat capacity of a point mass, the remaining heat capacity was successfully divided into functional grou p contributions at all temperatures. Including the results of our prev ious papers on alcohols and diols and carboxylic acids and sodium carb oxylates, the heat capacity contributions of the CH2, CH3, OH, COOH, ( COOH)(2), NH2, CONH2, COONa, and NH3Cl groups are now available, and t hese allow reasonably accurate predictions of the heat capacities of a ll aqueous compounds composed of these groups in this temperature rang e. (C) 1997 Academic Press Limited.