物理化学学报 >> 1992, Vol. 8 >> Issue (01): 52-58.doi: 10.3866/PKU.WHXB19920111

研究论文 上一篇    下一篇

停止-流动分光光度法研究铕(II)与二甲酚橙快速电子转移反应动力学

李大珍; 刘承敏; 肖养田; 杨惠星; 韩德刚   

  1. 北京师范大学化学系,北京 100875;北京大学化学系,北京 100871
  • 收稿日期:1990-09-04 修回日期:1991-03-02 发布日期:1992-02-15
  • 通讯作者: 李大珍

Studies on Kinetics of the Electron Transfer Reaction Between Eu(II) and Xylenol Orange by Stop-Flow Method

Li Da-Zhen; Liu Cheng-Min; Xiao Yang-Tian; Yang Hui-Xing; Han De-Gang   

  1. Chemistry Department, Beijing Normal University Beijing 100875; Chemistry Department, Beijing University 100871
  • Received:1990-09-04 Revised:1991-03-02 Published:1992-02-15
  • Contact: Li Da-Zhen

摘要: 用停止-流动分光光度法研究了Eu~(2+)与二甲酚橙(XO)间快速电子转移反应的动力学规律。求得了速控步骤的动力学参数。如反应级数(n=2)、几个不同温度下的速率常数(k_(278 K)=5.7×10~8 L·mol~-·s~(-1), k_(s38 K)=1.01×10~9 L·mol~(-1)·s~(-1))、活化能(E=7.6×10~3 J·mol~(-1)), 以及指前因子(A=1.5×10~(10) L·mol~(-1)·s~(-1)), 并判断出其为溶液中扩散控制型反应。根据实验现象与测试结果, 提出了Eu~(2+)与XO的反应分别在Eu~(2+)相对过量和在XO过量时的反应机理, 并判断了各反应步骤速率常数之间的相对关系。

关键词: Eu2+, 二甲酚橙, 停止-流动法, 反应

Abstract: The kinetics and mechanism of the reaction between Eu~(2+) and Xylenol orange (XO) in aqueous solution has been studied by means of stop-flow spectrophotometric method. The kinetic parameters of the rate-controlling step, i,e, reaction order (n=2), rate constant at various temperatures (k_(278 K)=5.7×10~8 L·mol~(-1)·s~(-1), k_(338 K)=1.01×10~9 L·mol~(-1)·s~(-1)…), activation energy (E=7.6×10~3 J·mol~(-1)) and preexponential factor (A=1.5×10~(10) L·mol~(-1)·s~(-1)) have been determined. It has been established that the electron transfer reaction between Eu~(2+) and XO is a diffusion controlled reaction.
The possible mechanisms of the reaction between Eu~(2+) and XO both in the presence of excess XO and Eu~(2+) also have been suggested. The relation between the rate constants of each step were estimated.

Key words: Eu2+, Xylenol Orange, Reaction, Stop-Flow Method