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
刘季铨 1郭慧林 1杨鹰 1郭晓辉1
作者信息
- 1. 西北大学化学与材料科学学院,西安 710127
- 折叠
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(φθ),以及如何利用Nernst方程由φθ计算电极电势(φ).教材中对于碱性条件下φBθ没有涉及,学生对φBθ不甚理解,乃至在由φBθ计算φ时可能得到错误的结果和结论.本文以水(H2O)氧化还原反应为例,从物质的标准生成Gibbs自由能变(∆fGmθ)出发计算φθ和φBθ,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φθ和φ的影响.这可为作为相关教学和科研的参考.
Abstract
In electrochemistry,φ can be calculated via φθ and Nernst equation.Current physical chemistry textbooks only provide substances'φθ 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 φθ(φBθ) from ∆rGmθ based on ∆fGmθ 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 φθ 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Key words
Redox reactions of water/Electrode potential calculation/φ-pH Diagram/Thermodynamic isotope effect引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
万方数据