Specific ionic interactions in the quaternary systems HCl?NaCl?KCl-water and HCl?NH4Cl?KCl-water at 25�C

Chemical equilibrium model of solution behavior and solubility in the H-Na-K-OH-Cl-HSO 4 -SO 4 -H 2 O system to high concentration and temperature 1 1Associate editor: D. J. Wesolowski

“…The model agreement with the low concentration (0.01-1.35 m HCl) ternary emf data of Harned and Hamer (1933) Leitzke and O'Brien (1968) Chan et al (1979) (25°C) and Macaskill et al (1978) (5°to 45°C), which are not used in the model parameterization, is excellent (sigma values for these four data sets are: 0.042, 0.030, 0.010 and 0.011). Chan et al (1979) report emf measurements for the quaternary HCl-KCl-NaCl-H 2 O system at 25°C. These measurements, which are for a total molality of 1 m, provide a good test of our low concentration predictions in this system.…”

Use of the Hygrometric Method for Determination of Water Activity of an Aqueous Hydrochloric Acid System at 298.15 K

“…The results of the activity coefficient of HCl in the aqueous hydrochloric acid solution of the system containing potassium chloride are compared to experimental data obtained by the emf method of diverse sources (Table ). ,− As is obvious in Table , the agreement between the predicted ionic mean activity coefficient of HCl and all of the data used for comparison is good over the experimental composition range. The estimated mean deviation of the stoichiometric ionic mean activity coefficient of HCl in the aqueous solution of the HCl–KCl–H 2 O system is less than 1.032%.…”

“…The hygrometric method allows the determination of water activity by measuring the relative humidity surrounding the studied solution . We used the spider-thin thread, which was kept tense over a Perspex support.…”

“…The hygrometric method allows the determination of water activity by measuring the relative humidity surrounding the studied solution. 14 We used the spider-thin thread, which was kept tense over a Perspex support. We pulverized some droplets of the reference solution of NaCl(aq) or LiCl(aq) on this thread, and the support was fixed to the cup (Figure 1).…”

“…The measurement of water activities of systems including the hydrochloric acid system by the isopiestic method is impossible, since hydrochloric acid is volatile. The emf method has been extensively applied for determination of the ionic mean activity coefficients of aqueous hydrochloric acid solution systems. ,,− However, the data of these studies were obtained for a limited range of concentrations. It should be noted that this method cannot be applied to aqueous hydrochloric acid solutions containing salts, such as CuCl 2 and FeCl 3 , which significantly affect the electrode potential .…”