水氧化还原反应中电极电势的计算和讨论  

Calculation and Discussion of Electrode Potentials in Redox Reactions of Water

作　　者：刘季铨 郭慧林[1] 杨鹰 郭晓辉 Ji-Quan Liu;Huilin Guo;Ying Yang;Xiaohui Guo(College of Chemistry and Materials Science,Northwest University,Xi’an 710127,China)

机构地区：[1]西北大学化学与材料科学学院,西安710127

出　　处：《大学化学》2024年第8期351-358,共8页University Chemistry

基　　金：2023年西北大学本科人才培养项目(XM05232458,XM05232428);中国博士后基金(2021M692609);2019年陕西省线下一流本科课程建设项目(物理化学)。

摘　　要：计算电极电势是电化学的必备技能。目前物理化学教材中,一般只给出了酸性条件下部分物质的标准电极电势(φ^(Θ)),以及如何利用Nernst方程由φ^(Θ)计算电极电势(φ)。教材中对于碱性条件下φ_(B)^(Θ)没有涉及,学生对φ_(B)^(Θ)不甚理解,乃至在由φ_(B)^(Θ)计算φ时可能得到错误的结果和结论。本文以水(H_(2)O)氧化还原反应为例,从物质的标准生成Gibbs自由能变(△_(f)G_(m)^(Θ))出发计算φ^(Θ)和φ_(B)^(Θ),结合酸(或碱)性条件下反应物种的分析,利用Nernst方程计算不同pH下的φ,给出φ–pH图。此外,还讨论了热力学同位素效应对φ^(Θ)和φ的影响。这可为作为相关教学和科研的参考。In electrochemistry,φ can be calculated via φ^(Θ)and Nernst equation.Current physical chemistry textbooks only provide substances’φ^(Θ) under acidic conditions and corresponding practices.Hence,the calculation of φ works well under acidic conditions.However,it becomes complicated under alkaline conditions for some substances cannot exist in acidic conditions.These might lead to incorrect results and confused conclusions.To address this issue,the present study calculates φ^(Θ)(φ_(B)^(Θ))from △_(r)G_(m)^(Θ) based on △_(f)G_(m)^(Θ) of involved substances in redox half reaction.Then,φ at different pH is calculated via Nernst equation,resulting in a φ−pH diagram.Moreover,thermodynamic isotope effects on φ^(Θ)and φ are included.This may serve as a reference for teaching and research purposes.

关 键 词：水氧化还原反应 电极电势计算 φ–pH图 热力学同位素效应 

分 类 号：G64[文化科学—高等教育学] O6[文化科学—教育学]