【摘要】 在酸性4M氯化钠溶液中得到一很好的锑(Ⅲ)可逆扩散波。此波随加入乙二胺四乙酸量而减低、且稍向负电位移动,在更负电位处又出现另一不可逆波,二波之和与溶液pH和乙二胺四乙酸的浓度无关。经多种实验的验证,第一波(较正波)为可逆三电子反应动力波,是受络合物SbY的离解速率控制。用Koryta提出的动力波半波电位求络合物稳定常数的方法测定锑(Ⅲ)-乙二胺四乙酸络合物的稳定常数和反应自由能等热力学函数;用Hanus近似法推出动力电流方程式,测定络合物离解速率常数和反应活化能;并探讨各相应的电极过程。更多还原

【Abstract】 The polarographic behaviour of antimony(III) complex with ethylenediaminetetraaceticacid (EDTA), including the calculation of stability constants, thermodynamic functions,and the mechanism of the complex formation, has not yet been studied in detail. In acidic4 M sodium chloride solution, there is one cathodic diffusion wave corresponding to threeelectrons reversible electrode reaction of antimony(III) at about-0.132 V (vs. S. C. E.)and pH 1.63. If to a strongly acidic solution EDTA is added even in high concentra-tion, it exerts practically no influence on this wave. But if it is added to weakly acidicsolutions (e. g. pH>2), there appears another wave which corresponds to the three elec-trons electrode reaction as before but at more negative potentials (e. g. at about--0.55 Vat pH 2). If either the pH or the concentration of EDTA is reduced, the height of thesecond (more negative) wave decreases, while the first one appears again. The sum ofboth waves is constant and is independent of the concentration of EDTA and the pHvalue. The first wave is three electrons reversible electrode reaction and is kinetically con-trolled, whereas the sum of both waves is diffusion controlled. This was proved by thedependence of the wave height on the height of the mercury reservoir (Fig. 1), by thetime beater (Fig. 2), by the temperature dependence (Fig. 3), by the hanging mercury dropelectrode (Fig. 4), and by the polaroscope (Fig. 5). From the above experiments, we conclude that the second wave corresponds to thereduction of SbY complex while the first one to the reduction of antimonous ion whichis controlled by the dissociation rate of SbY complex. Koryta’s method enables us to calculate the stability constant and the thermodynamicfunctions of SbY complex from the shift of half-wave potentinl of kinetic wave at givenconditions (concentrations of sodium chloride and EDTA, pH, etc.). By Hanus’s method,it is possible to calculate the dissociation velocity constant of the SbY complex from thekinetic current. The mechanism of the whole process is discussed and can be expressedby the scheme described in the Chinese text.更多还原