电位法研究锡(Ⅱ)-氯离子的配位平衡

Potentiometry Study of Coordination Equilibrium of Sn(II)-Cl^-

关于Sn(Ⅱ)-Cl^-配合物的稳定常数及其最大配位数的报道,由于不同作者的实验方法和数据处理方法不同,测定结果也不尽一致。本文的工作是采用防止Sn(Ⅱ)氧化措施,用NaClO_4,HClO_4控制离子强度,加入NaCl作配位剂,测定浓差电池的电动势,求出各级稳定常数,并确定最大配位数。

In orde to provide fundamental data for the thermodynamic analysis of the Sn(Ⅱ)- Cl^--H_2O system, potentiometry has been used to measure the over-all stability constants of coordinate ions for the Sn(Ⅱ)-Cl^- system at t=25℃ and ionic strength I=3. The over-all stability constants for stepwise reactions are as follows: lg β_1=1.202, lg β_2= 1.288, lg β_3=2.369, lg β_4=1.968. The maximum coordination number N has been determined to be 4. The equilibrium concentration profile of coordinate ions for this system is also illustrated.