物理化学学报 >> 1986, Vol. 2 >> Issue (01): 30-36.doi: 10.3866/PKU.WHXB19860105

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用玻璃电极测定直到15 m的浓盐酸体系的活度系数

赵凯元; 雷鸿毅   

  1. 北京大学化学系物理化学教研室
  • 收稿日期:1985-02-13 修回日期:1985-10-19 发布日期:1986-02-15

DETERMINATION OF MEAN ACTIVITY COEFFICIENTS OF HYDROCHLORIC ACID IN CONCENTRATED SOLUTIONS UP TO 15 m WITH GLASS ELECTRODE

Zhao Kaiyuan; Lei Hongyi   

  1. Department of Chemistry, Peking University, Beijing
  • Received:1985-02-13 Revised:1985-10-19 Published:1986-02-15

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摘要： 本文在25 ℃下, 对0.01844—15.02 mol kg~(-1)浓度范围内的盐酸体系, 用自制Ag|AgGl电极和氢电极, 测定了Harned电池的电动势。在此基础上, 以玻璃电极代替氢电极, 测量上述盐酸体系的电动势, 计算了HCl的平均活度系数和H_2O的活度。实验结果表明, 玻璃电极在浓盐酸体系的“标准电势”是稳定的, 且遵从Nernst响应, 重现性良好, 响应速度快; 在高浓度和稀溶液中交替测量时, 电势无明显偏差。这说明电极有较好的可复性。求得的HCl的活度系数与文献值偏差小于1.2％。玻璃电极的“标准电势”的标准偏差为0.016％。

Abstract: Mean activity Coefficients of HCl in concentrated hydrochloric acid solutions are determined by measuring emf′s of following cells (A). Ag-AgCl/HCl(m)/H_2(P)/Pt(black) (B). Ag-AgCl/HCl(m)/pH-glass electrode for HCl molalities from 0.01844 to 15.02 tool kg~(-1) at 25 ℃. Using observed emf data of ceils (A) and (B), mean activity coefficients of HCl are calculated, and their deviations are less than 1.2%. Within this molality range, “standard potential” E_G~0 of pH-glass electrode is a constant and its standard deviation is equal to 0.016%. The pH-glass electrode used has good reproducibility. Therefore, it is possible to determine the activity coefficients in high concentrated hydrochloric acid solution by using pH-glass electrode.
For concentrated hydrochloric acid in molality range 0.1844—15.02 mol kg~(-1) at 25 ℃, the lograrithm of activity coefficients of HCl can be expressed adquately by the equation:
logγ±=-0.5115/(1+1.471)+0.1069 m+7.412×10~(-3) m-6.637×10~(-4) m~3
+1.586×10~(-5) m~4
where m is the HCl concentration in molality, γ± is its activity coefficients. Using this equation, activities of solvent H_2O have been calculated.