An Empirical Equation for the Solubility of Nonpolar Gases and Vapors in Concentrated Water-Acid and Water-Salt Solutions


The equilibrium gas/solution partition coefficients α = lim(cgas/cliq) at Cgas → 0 for methane in the system water-sulfuric acid were measured over the entire range of compositions at 298 K. To describe the solubility of gases and vapors of nonpolar substances in water-electrolyte systems, the equation (log α)φ E ≡ log α - φwlogαw - φelogαe = Lφ(VE/V) was proposed. This equation relates the excess parameter (log α)E expressed in terms of volume fractions of water φw and the electrolyte φe to the excess volume VE=V-xwVw-xeVe (compression) of the two-component water-electrolyte solvent, where xw and xe are the mole fractions of water and electrolyte, αw, and αe, Vw, and Ve refer to the pure components. It was found that this equation is not sensitive to the form of representation of the electrolyte component, which can be an individual substance (for example, H2SO4) or a solvate (H2SO4·nH2O). For solutions of oxygen and vapors of saturated hydrocarbons in water-sulfuric acid and water-phosphoric acid solvents and for solutions of carbon dioxide in NaCl and KCl aqueous solutions at 298 K, the coefficient Lφ was found to be a unique linear function of the molar volume of the solute. An analysis of the available results suggests that the proposed equation is universal. It was demonstrated that the excess properties of electrolyte solutions are more closely described in terms of volume fractions rather than mole fractions.



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© 2002 Maik Nauka-Interperiodica Publishing, All rights reserved.

Publication Date

01 Jan 2002

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