An Investigation of the Equilibria Existing in Gas-Water Systems Forming Electrolytes

Abstract

The data and theoretical treatment contained in this paper are the continuation of a series of researches instituted to investigate the equilibria existing in certain gaseous-aqueous systems. In this work the vapor pressures and electrolytic conductivities of aqueous solutions of sulphur dioxide, carbon dioxide, and ammonia have been measured with greater precision than ever before over a temperature range from 0 to 25 °C. and over a concentration range where their respective vapor pressures do not exceed one atmosphere. From the data thus derived, equilibria relations have been calculated and certain changes have been made in the mode of theoretical procedure involved in this type of calculation.With regard to the equilibria existing in the three systems, the conclusions drawn may be summarized as follows: Practically all of the ammonia exists in the combined form and practically all the carbon dioxide exists as free carbon dioxide in the aqueous solutions in the temperature range investigated. The amounts of free and combined sulphur dioxide are of the same order of magnitude and the relative amount of combined and free sulphur dioxide can be calculated approximately, the latter increasing markedly with rising temperature. The true dissociation constant can therefore be found for ammonium hydroxide, can be estimated for sulphurous acid, but cannot be calculated for carbonic acid from the available data.

Spectrophotometric measurement of the vapour-liquid equilibria of (sulphur dioxide + water)

“…These results are also in good agreement with the measured ones. (19)(20)(21) Parkinson (22) measured the partial pressures of SO 2 at T = 294.25 K. His values agree within experimental error with our calculations.…”

“…(4,18) It may be seen that values quoted by Perry (2) are too high. Figure 5 and 6 compare our results at T = 298.15 K with experimental values (5,(19)(20)(21) and correlations (4,13,18) over a large molality range (up to 1 mol·kg −1 ). In dilute aqueous solutions, the experimental results of Johnstone and Leppla (5) agree very well with our calculated values.…”

“…The excellent agreement between the measured (19) at T = 298.15 K; ×, Morgan and Maass (20) at T = 298.15 K; $, Conrad and Beuschlein (21) at T=298.15 K; W, Rabe and Harris (23) at T = 313.15 K; q, Vosolsobe et al (24) at T = 313.15 K; w, Perry and Green (2) at T = 313.15 K; ----, Pearson et al; (4) --, this work.…”

“…where i = SO 2 (aq), HSO From equation (16), the definition of pH, and putting the activity coefficient for SO 2 (aq) and the activity of water equal to unity follow the expressions for the mole fractions of ions: were then calculated at a given temperature from the known equilibrium constants of reactions (3), (4) and (5) using equations (20), (21) and (22) and following an iteration procedure similar to that described for the calculation of vapour-liquid equilibria of (sulphur dioxide + water) previously. Figure 2 shows the equilibrium concentrations of various species as the fraction of total sulphur at different pH values at T = 293.15 K. It shows that the formation of SO 2− 3 at pH below 4 is negligibly small.…”

Mass transfer of NH3 into water at environmental concentrations

“…The value of H for NH, has been measured or estimated by several investigators (Morgan et al, 1931;McKay, 1971, Edward et al, 1975Hales, 1979). In this paper, the value of H measured by Hales was selected for calculation of K at 25"C, since it was determined at very low concentrations of NH3.…”