An alternative method is presented, which is independent of any physicochemical model of the electrolyte solution, for the evaluation of the mean ionic activity coefficient in molal scale, ${\gamma }_{\pm i}$ (i: 2,3), of the solutes of a ternary solution (1–2–3), starting from experimental data of the osmotic coefficient on composition ϕ^exp(m,x_i). It is based on the dependence of ln ${\gamma }_{\pm i}$ on ϕ originally derived by H.A.C. McKay and confirmed by S.G. Canagaratna and M. Maheswaran as a particular solution of Gibbs-Duhem equation for multicomponent systems. Its application involves the integration of both ϕ and its derivative $\partial \varphi /\partial m_i$, so that it requires a very precise correlation of the dependence ϕ^exp(m,x_i). Therefore, in order to achieve the required precision, the theoretical expression ϕ(m,x_i) is developed as the sum of three contributions, (i) ϕ^DH: the limiting behaviour given by the Debye-Hückel equation for multicomponent systems, (ii) Δϕ^DDH: the sum of the deviations to the Debye-Hückel behaviour of the corresponding binary solutions (1–2 and 1–3) and (iii) Δϕ^M: a contribution of mixing effect. Finally, introducing the resulting ϕ(m,x_i) into the Gibbs-Duhem equation and operating, the corresponding expression of ln ${\gamma }_{\pm i}$ (m,x_i) is derived. The capacity of the ϕ(m,x_i) equation to correlate the dependence ϕ^exp(m,x_i), the methodology employed to obtain the parameters values, as well as the ln ${\gamma }_{\pm i}$ (m,x_i) resulting dependence are illustrated through its application to the analysis of two ternary systems.

提出了一种替代方法，它独立于电解质溶液的任何物理化学模型，用于评估摩尔尺度的平均离子活度系数， ${\gamma }_{\pm \mathrm{一世}}$( i : 2,3), 三元溶液 (1–2–3) 的溶质，从渗透系数的实验数据开始，组成ϕ ^exp ( m, x _i )。它基于 ln 的依赖性${\gamma }_{\pm \mathrm{一世}}$on φ最初由 HAC McKay 推导出，并由 SG Canagaratna 和 M. Maheswaran 确认为多分量系统 Gibbs-Duhem 方程的特解。它的应用涉及ϕ及其导数的积分$\partial \phi /\partial {米}_{\mathrm{一世}}$，因此，它需要的依赖的非常精确的相关性φ ^EXP（M，X_我）。因此，为了达到所要求的精度，则理论表达式φ（M，X_我）被开发为三个贡献的总和，（ⅰ）φ ^DH：由德拜-休克尔方程的多组分系统给定的限制的行为，（ ii) Δϕ ^DDH：对应二元解（1-2 和 1-3）的 Debye-Hückel 行为偏差的总和和 (iii) Δϕ ^M：混合效应的贡献。最后，引入由此产生的ϕ ( m,x _i) 代入 Gibbs-Duhem 方程并运算，ln 的对应表达式 ${\gamma }_{\pm \mathrm{一世}}$（M，X_我）被导出。所述的容量φ（M，X_我）方程来的依赖相关联φ ^EXP（M，X_我），用于获得所述参数的值的方法，以及在LN${\gamma }_{\pm \mathrm{一世}}$（M，X_我）得到的依赖性是通过它的应用程序在两个三元系统的分析中示出。