Activity coefficients of strong electrolytes in multicomponent aqueous solutions

Abstract The quantity T12 here called the reduced activity coefficient is related to Γ 12 the mean activity coefficient of a strong electrolyte 12 as follows:\documentclass{article}\pagestyle{empty}\begin{document}$$\Gamma _{12} = \gamma 12^{{1 \mathord{\left/ {\vphantom {1 {z_1 z_2 }}} \right. \kern-\nulldelimiterspace} {z_1 z_2 }}}$$\end{document} where z 1 and z 2 are the charge number on the ions. The value of Γ 12 for electrolyte 12 in an aqueous solution containing the three ions 1, 2, and 3, such as Na + Cl − and Ba ++ , is to be calculated as follows:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}\Gamma _{12} = {\rm log}\Gamma ^ \circ _{12} + {\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}\left({{\rm X}_{\rm 3} } \right){\rm log}\left({{{\Gamma ^ \circ _{32} } \mathord{\left/ {\vphantom {{\Gamma ^ \circ _{32} } {\Gamma ^ \circ _{12} }}} \right. \kern-\nulldelimiterspace} {\Gamma ^ \circ _{12} }}} \right)$$\end{document} Here Γ° 32 and Γ° 12 are for the indicated electrolytes, namely NaCl and BaCl 2 in this example, at the total ionic strength of the mixture. The term X 3 represents the fraction m 3 z 3 2 /(m 1 z 1 2 + m 3 z 3 2 ) in which m represents the molality of the indicated ion. Fair success is usually attained with this equation in predicting γ, even at high electrolyte concentrations. Similar equations are proposed for aqueous solutions containing four or more ions.