Water activities, osmotic and activity coefficients in aqueous chloride solutions at T = 298.15 K by the hygrometric method

摘要

Water activities of aqueous electrolyte solutions of HCl(aq), LiCl(aq), NaCl(aq), KCl(aq), CsCl(aq), NH_4Cl(aq), MgCl_2(aq), CaCl_2(aq), and Bacl_2(aq) have been determined at T = 298.15 K by the hygrometric method, and at molalities ranging from 0.2 mol(centre dot)kg~(-1) to saturation. From measurements of droplets diameters of reference NaCl(aq) or LiCl(aq), the dependence of relative humidity on solute concentrastion was determined. The data on the relative humidities allow the deduction of water activities and the osmotic coefficients at different molalities. Osmoti coefficient data have been described by the ion interaction model of Pitzer. The ion interaction parmaeters were also determined for each of the studied salts. With these parameters, the solute activity coefficients can be predicted. Our present results have been compared with reported thermodynamic data.