Apparent molar volumes and heat capacities of aqueous magnesium chloride and cadmium chloride at temperatures from 278.15 K to 393.15 K at the pressure 0.35 MPa: a comparison of ion-ion interactions

Apparent molar volumes V-phi and apparent molar heat capacities C-p,C-phi W ere determined for aqueous solutions of magnesium chloride (MgCl2) and cadm ium chloride (CdCl2) at molalities m = (0.01 to 1.0) mol . kg(-1), at T = 2 78.15 K to T = 393.15 K, and at the pressure 0.35 MPa. Apparent molar volum es were calculated from densities obtained using a vibrating-tube densimete r. Apparent molar heat capacities were obtained using a twin fixed-cell, po wer-compensation, differential-output, temperature-scanning calorimeter. Th ese results were used to create the surfaces (V-phi, m, T) and (C-p,C-phi m , T) which were fitted by regression. Differences in ion-ion interactions f or MgCl2(aq) and CdCl2(aq) are observed by comparison of the regression sur faces. (C) 2000 Academic Press.