汽液平衡法研究NaI在甲醇-苯中的活度系数

测定了甲醇-苯-NaI体系常压汽液平衡数据,采用双标准检验法对数据进行检验,检验结果全部合格.假定NaI的平均活度系数可表示为盐浓度平方根(m1/2)的幂级数,采用全部合格的汽液平衡数据拟合出幂级数中的各项系数,从而获得在双液比固定条件下盐在非水混合体系的活度系数.计算结果表明正常泡点温度下在具有固定双液比的甲醇-苯混合溶剂中NaI的平均活度系数随盐浓度的增加先减小,经过一个极小值后又增加.此法可推广于其它非水混合溶剂中电解质活度系数的测定.

Study of Activity Coefficients for Sodium Iodide in Methanol-benzene System by Vapor-liquid Equilibrium Measurements

By measuring the vapor-liquid equilibrium of methanol-benzene-NaI and verifying the data by means of ternary Gibbs-Duhem equation,the data of the vapor-liquid equilibrium of methanol-benzene-NaI were in agreement with both criterious.It is supposed that the mean activity coefficients of NaI may be represented by power of m~(1/2).Then each parameter of power equation was fitted.The results of calculation show that at the equilibrium temperature and pressure the activity coefficients of NaI in methanol-benzene system with fixed composition decrease at first as its concentration increases,then they pass a minimum and increase gradually again.This method is adapted to determination of electrolytical activity coefficients in non-aqueous solvents.