用氯离子选择电极测定浓盐酸的活度系数及氯离子吸附效应的探讨

在25 ℃下, 用氯离子选择电极与玻璃电极组成电池测定了0.00498～15.02 molkg~(-1)浓度范围盐酸体系的电势, 发现用Nernst方程计算出的活度系数与文献值偏差极大。用氯离子吸附原理和形成吸附对的平衡原理导出的电势方程, 由此计算出的盐酸活度系数与文献值十分一致, 这表明氯离子在电极表面发生了特性吸附作用。

DETERMINATION OF ACTIVITY COEFFICIENTS IN CONCENTRATED HYDRO-CHLORIC ACID WITH Cl-ISE AND STUDY OF ADSORPTION OF Cl-ION

In this paper the electromotive force of following cell: glass electrode |HCl (m)|Cl-ISE has been measured at molalities of HCl solutions from 0.005 to 15 mol kg~(-1) at 25 ℃. We found that Cl~--ISE Nernst's equation isn't followed. The mean activity, coefficients of HCl, calculated according to Nernsts equation are less than 1 in all molality range. On the basis of these facts, chemical adsorption of Cl-ion has been discussed. We belive that in concentrated hydrochloric acid Cl-ion are adsorbed on the surface of Cl-ISE, and form Ag~+-Cl~- and Ag~+-Cl_2~(2-). Potentails of Cl-ISE are determined by following equation: ε=ε°-Slog γ_±m/(1+K_(γ_±)m)], (K=0.219), The activity coefficients of HCl which, calculated by this equation, are agree with that reported in literature.