碘分配系数及平衡常数的计算

Calculation of the Distribution Coefficient of Iodin and the Reaction Equilibrium Constant

在碘和碘离子反应平衡常数的测定实验中,由于碘的水溶液较难配制且与碘四氯化碳溶液构成的复相系统不易建立平衡,文章因此采用两种不同浓度的KI溶液与碘的四氯化碳溶液构成两个复相平衡系统,采用氧化-还原滴定方法确定各组分平衡浓度,并在此实验基础上推导出了碘的分配系数及反应平衡常数的计算公式。实验表明,采用上述方法建立的复相系统较易达到平衡,实验测定的分配系统和平衡常数更为准确。

In the experiment of determination of the equilibrium constant of the reaction of iodin and iodin ion, for the iodin-in-water solution hardly formed and the equilibrium of the diphase system consisting of the iodin-in-water solution and the iodin-in-CCl4 solution hardly established, a new method was proposed in the paper to build up two diphase equilibrium systems by using two KI solutions of different concentrations and two iodin-in-CCl4 solutions. The oxidation-reduction titration method was adopted to determine the equilibrium concentrations of all components. Based on the above experiment, the calculation expressions of the distribution coefficient of iodin and the reaction equilibrium constant were deduced. The experiment result showed that the equilibrium of the diphase systems was easy to established and the distribution coefficient and the equilibrium constant determined by experiment was more exact.