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 300 K to 525 K and a pressure of 28 MPa

Abstract

The apparent molar heat capacities of dilute aqueous solutions of propylamine, 1,4-butanediamine, 1,6-hexanediamine, propylamine hydrochloride, propionamide, pyridine, and sodium benzenesulfonate were measured at 300 K<T<525 K andp=28 MPa. Corrections for hydrolysis or dissociation reactions and relaxation effects were applied where necessary, and the results were extrapolated to infinite dilution to obtainCp,2∞. After subtracting the heat capacity of a point mass, the remaining heat capacity was successfully divided into functional group contributions at all temperatures. Including the results of our previous papers on alcohols and diols and carboxylic acids and sodium carboxylates, the heat capacity contributions of the CH2, CH3, OH, COOH, (COOH)2, NH2, CONH2, COONa, and NH3Cl groups are now available, and these allow reasonably accurate predictions of the heat capacities of all aqueous compounds composed of these groups in this temperature range.