电势-pH图在判断高锰酸钾反应产物中的应用

Application of Potential-pH Diagram in Judging Reaction Products of Potassium Permanganate

针对无机化学实验的性质实验模块中,关于溶液酸碱度对高锰酸钾与亚硫酸钠间氧化还原反应产物的影响,以及反应放置一段时间后化学现象发生变化等问题,利用能斯特方程推导出相关电对的电极电势随pH变化表达式,通过电势-pH图讨论了Mn体系相关物质在水中的热力学稳定性和存在形式,讨论了在不同酸度下KMnO_(4)作为氧化剂,与Na_(2)SO_(3)反应生成不同产物的原因,并从理论上探讨了放置一段时间后,在特定的酸碱性条件下因某种反应物过量等因素而观察到产物继续会转化成MnO_(2)、Mn(OH)_(2)等的可能性。

Aiming at some questions in the properties experiment of inorganic chemistry about the influence of solution pH on the redox reaction products between potassium permanganate and sodium sulfite, the chemical phenomenon changes after the reaction products being placed for a period of time, etc., the functions between electrode potential of related redox couples & pH were derived by Nernst equation, and the thermodynamic stability and existence forms of Mn system related substances in water were discussed by potential-pH diagram. The reasons for the reaction of KMnO4as oxidant with Na_(2)SO_(3) to produce different products under different pH were discussed. In addition, the possibility of the products being converted into MnO_(2), Mn(OH)_(2), etc., by placing for a period of time was discussed theoretically under certain pH condition and the excess of some reactants.