Determination of the Pitzer Interaction Parameters at 273.15 K from the Freezing-Point Data Available for Solutions of Uni-Univalent Electrolytes

Abstract

A novel calculation method (see the article in Ind. Eng. Chem. Res. 2014, 53, 5608–5616) was applied in this work to evaluate the ion interaction parameters for the Pitzer model from freezing points of aqueous solutions of pure electrolytes. The freezing-point depression data from aqueous solutions of salts consisting of chloride, bromide, nitrate, chlorate, perchlorate, formate, and acetate ions as anions and lithium, sodium, and potassium ions as cations were used in the present study. The literature data from the research group of Scatchard (J. Am. Chem. Soc. 1932, 54, 2676−2695; 1933, 55, 4355−4362; and 1934, 56, 805−811) were available for the calculations. Additionally, the parameters for salts of ammonium ion with chloride, bromide, iodide, and nitrate ions were determined but the data of this group (J. Am. Chem. Soc. 1932, 54, 2696−2705) are probably not reliable in these cases. The parameter values obtained using this method for solutions of the other salts than those of ammonium salts predict more accurately the experimental data than the ordinarily used Pitzer parameters and their temperature derivatives. Up to a molality of 0.5 mol·kg–1 in the former case, the errors are usually less than ±0.001 K, but in the latter case, they can be as high as ±0.02 K. The ordinarily used parameter values have been most often determined using calorimetric measurements.