In this article, the average activity coefficients of KCl in the KCl–KI–H₂O ternary system at 298.15 K were determined using the cell potential method with a cell of a potassium-ion combination ion selective electrode (ISE) and a chlorine-ion combination ion selective electrode (ISE) without a liquid junction, Also, we chose the total ionic strength I range from 0.0100 to 1.0000 mol·kg^–1 for different ionic strength fractions y_b of KI with y_b = (0.2, 0.4, 0.6, 0.8). The experimental results show that the mean activity coefficients of KCl can be calculated well by using the Pitzer models and Nernst equation. Furthermore, the mixing Pitzer ion interaction parameters of θ_Cl, I and ψ_K, I, Cl were fitted using Pitzer’s equations, and the two parameters were applied to calculated the mean activity coefficients of KI in the KCl–KI–H₂O ternary system. Accordingly, the osmotic coefficients, water activities, and excess Gibbs free energies in the mixtures were studied in this mixed system.

中文翻译：

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三元系统 KCl-KI-H ₂ O 在 298.15 K 的热力学研究，采用细胞电位法

在本文中，KCl-KI-H ₂ O 三元体系中KCl在 298.15 K的平均活度系数是使用电池电位法用钾离子组合离子选择电极 (ISE) 和氯-离子组合离子选择电极 (ISE) 不带液接界，此外，我们选择总离子强度I范围为 0.0100 至 1.0000 mol·kg ^–1，用于KI 的不同离子强度分数y _b，y _b = (0.2, 0.4, 0.6、0.8）。实验结果表明，利用Pitzer模型和Nernst方程可以很好地计算KCl的平均活度系数。此外，θ 的混合 Pitzer 离子相互作用参数_{Cl, I}和ψ _{K, I, Cl}使用Pitzer 方程拟合，并应用这两个参数计算KCl-KI-H ₂ O 三元体系中KI 的平均活度系数。因此，在该混合体系中研究了混合物中的渗透系数、水活度和过量吉布斯自由能。