电解生成亚铁离子返滴定法测定消毒液中过氧化氢含量的数字化实验

Digital Experiment on Determination of Hydrogen Peroxide Concentration in Disinfectant by Back Titration Using Ferrous Ion Produced by Electrolysis

氧化还原与电解的相关知识是中学化学学习的重点内容。应用自主研制的MXLab21先进数字化实验系统电解Fe_(2)(SO_(4))_(3)溶液,用电解生成的Fe^(2+)直接滴定KMnO_(4)溶液以测定其浓度,再用返滴法测定消毒液中H_(2)O_(2)的含量。对恒电流电解的最佳条件如Fe_(2)(SO_(4))_(3)溶液浓度及电解电流大小进行了优化。该数字化实验系统相比较于常规数字化仪器(或手持技术)的优越性在于其自带电解、搅拌及控制系统,能在电解的同时利用电生物质实现对待测物质的准确测定,测定时间短(不超过4 min)。本实验采用预设终点电势值的方法自动估计滴定终点,不但便捷准确,且呈现出的实时直观的电势和电量随时间变化的动态曲线便于学生理解电解及氧化还原滴定反应的微观本质,对中学化学教学及化学学科核心素养的培养具有重要价值。

Redox and electrolysis are the key contents of middle school chemistry.The MXLab21 advanced digital experimental system developed by our project team was used to electrolyze Fe_(2)(SO_(4))_(3)to generate Fe^(2+),which was used to determine the concentration of KMnO_(4)through direct titration method,and the concentration of H_(2)O_(2)in the disinfectant through the back titration method.The experimental conditions for constant current electrolysis including the concentration of Fe_(2)(SO_(4))_(3)and the magnitude of electrolysis current had been optimized.Compared with the conventional digital instrument or handheld technology,the advantage of this digital experiment system was that it had its own electrolysis,stirring and control system.It could use substances produced by electrolysis to achieve accurate determination of the substance while electrolyzing,and the determination time was short(no more than 4 min).The end point of titration was estimated automatically by presetting the end point potential value,which was not only convenient and accurate,but also presented a real-time and intuitive dynamic curve of potential and electric quantity changes with time to facilitate students to understand the microscopic nature of electrolysis and redox titration reactions.It was of great value for middle school chemistry teaching and the cultivation of chemistry discipline core literacy.