大学化学 >> 2023, Vol. 38 >> Issue (8): 283-292.doi: 10.3866/PKU.DXHX202208117

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氧化还原滴定方法理论新说

岳宣峰1,*(), 秦丹1, 张可欣1, 刘阳禾1, 王梁宇1, 张婷1, 张延妮2,*()   

  1. 1 陕西师范大学化学化工学院, 陕西省生命分析化学重点实验室, 西安 710062
    2 陕西师范大学药用资源与天然药物化学教育部重点实验室, 西安 710062
  • 收稿日期:2022-08-26 录用日期:2022-09-22 发布日期:2022-11-03
  • 通讯作者: 岳宣峰,张延妮 E-mail:xfyue@snnu.edu.cn;ynzhang@snnu.edu.cn
  • 基金资助:
    陕西省自然科学基础研究计划(2022JZ-54);陕西师范大学教学改革研究项目(22JG35);陕西师范大学大学生创新训练项目(202210718054);陕西师范大学大学生创新训练项目(CY2022018)

New Theory for Principle of Redox Titration

Xuanfeng Yue1,*(), Dan Qin1, Kexin Zhang1, Yanghe Liu1, Liangyu Wang1, Ting Zhang1, Yanni Zhang2,*()   

  1. 1 Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China
    2 Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, Shaanxi Normal University, Xi'an 710062, China
  • Received:2022-08-26 Accepted:2022-09-22 Published:2022-11-03
  • Contact: Xuanfeng Yue, Yanni Zhang E-mail:xfyue@snnu.edu.cn;ynzhang@snnu.edu.cn

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摘要：

为了改造氧化还原滴定分析方法的标度，从而逐步建立统一的滴定分析标度计算式，提出了相对电子浓度$ {{R}}_{{\text{e}}^{{-}}} $的概念，基于此发展了以$ \text{p}{{R}}_{{\text{e}}^{{-}}} $为监测标度的氧化还原滴定方法新理论。该理论描述了氧化还原半反应的平衡，推导了氧化还原滴定标度$ \text{p}{{R}}_{{\text{e}}^{{-}}} $的计算通式，探索了该标度在滴定过程中的一般变化规律，重新梳理了指示剂的指示原理。以Ce4+滴定Fe3+溶液为例，演绎了如何简单绘制滴定曲线、计算滴定突跃范围、判断可否直接准确滴定，讨论了氧化还原反应条件平衡常数$ {{K}}_{\tau }^{{\rm{ \mathsf{ ϴ} }}{ʹ}} $的大小对滴定分析的影响。

关键词: 氧化还原滴定, 相对电子浓度, 滴定曲线, 电子指示剂, 准确滴定

Abstract:

To transform the scale of redox titration for a unified formula of the titration scale, a relative concentration of the aqueous electron $ {{R}}_{{\text{e}}^{{-}}} $ is proposed, and a new theory for redox titration is then developed with $ \text{p}{{R}}_{{\text{e}}^{{-}}} $ as its monitoring scale. This new theory addresses the balancing of the semi-redox-reaction, provides the general formula for calculating $ \text{p}{{R}}_{{\text{e}}^{{-}}} $, investigates the general variation of $ \text{p}{{R}}_{{\text{e}}^{{-}}} $ in titration, and reintroduces the principle of an electron indicator. In this study, the titration of Ce4+ to Fe3+ solution is used as an example to deduce the following aspects: the approach for drawing titration curves, calculation for titration jump ranges, and criterion of direct and accurate titrations. Finally, the effect of $ {{K}}_{\tau }^{{\rm{ \mathsf{ ϴ} }}{ʹ}}, $which is the conditional equilibrium constant of a redox reaction, on titrimetric analysis is discussed.

Key words: Redox titration, Relative concentration of aqueous electron, Titration curve, Electron indicator, Accurate titration