Aktivitätskoeffizienten und Dissoziationskonstanten wäβriger Salpetersäure und Überchlorsäure

Abstract

Determinations of partial vapour pressures and isopiestic measurements have been carried out on aqueous solutions of nitric acid and of perchloric acid. In the case of nitric acid the measurements cover the rangc it1 = 2-28 mol kg-l at 25 "C, 50 "C and 75 "C; for perchloric acid the range rrr = 0.1-14 mol kg-1 was studied at 10 "C and 40 "C and rn = 0.1-16 mol kg-1 at 25 "C. Osmotic coefficients, stoichiometric mean activity coefficients and related thermodynamic functions arc derived from the experimental data. In the case of perchloric acid at 25 "C values of the relative partial molar enthalpy of the electrolyte were also obtained. Thc stoichiometric activity coefficients at 25 "C for both systems are fairly well represented by a previously proposed equation with three adjustable parameters. With the aid of literature data for the degrees of dissociation of both acids, values of the following quantities were obtained: dissociation constants, standard affinities, enthalpies and entropies of dissociation, mean ionic activity coefficients and activity coefficients of the undissociated portion of electrolytes. Einleitung

The solubility and behaviour of acid gases in the marine aerosol

“…The data of both Haase et al (1965) and the International Critical Tables show a trend toward higher K~ with increasing concentration. Because of this only the data of Davis and DeBruin (1964), Vandoni and Laudy (1952) and Yakimov and Mishin (Hala et al, 1968) have been used to calculate a mean KH at 25 °C of 2.45 × l0 6 mol 2 kg -2 atm -~, standard deviation 0.18 x 10 6.…”

“…Haase et al (1965) have also made measurements from 2.0 to 28.0 mol kg -1 at 25 °, 50" and 75 °C; and at 20°C Potier (1956) has measured partial pressures at aqueous phase concentrations from 7.0 to 23 mol dm -3 and Vandoni and Laudy (1952) from 16 to 80 mole %. Mean activity coefficients of HNO3 at 25 °C are available up to concentrations of 28 mol kg -l (Hamer and Wu, 1972).…”

“…The data of Potier (1956) appears to be discordant with that of the other workers, otherwise agreement is good. It should be noted that the partial pressure and activity coefficient data are not independent of one another; Hamer and Wu (1972) Hamer and Wu (1972) and the partial pressure data of: (1) Vandoni and Laudy (1952), Davis and DeBruin (1964), (3) International Critical Tables (1926), (4) Haase et al, (1965), Potier (1956), (6) Yakimov and Mishin (Hala et al, 1968). Both (1) and (5) were corrected to 25 °C.…”

“…(1964) and Haase et al (1965) data as sources. The data of both Haase et al (1965) and the International Critical Tables show a trend toward higher K~ with increasing concentration.…”

The Water Activity and Free Water Mole Fraction in Perchloric Acid

“…Namely, they were carried out at 25°C by isopiestic [4][5][6] and dynamic [7] methods. In addition, measurements were carried out at 0°C by isopiestic [8] and at 50°C by psychrometric [8] methods, as well as at 0, 10, 20, 30, 40 and 50°C by the static [2] method.…”