Study of Unconventional Valence Compounds of Manganese Elements

Manganese is an important metal element and is widely used in various fields such as industry and medicine. However, there is a lack of systematic introduction of manganese and its compounds in secondary school textbooks The purpose of the experiment is to prepare several unconventional valence compounds of manganese elements, to clarify the intrinsic connection between the oxidation states of manganese, and to help students recognize the various oxidation states of manganese. In this study, three sets of experiments on the interconversion of different valence states of manganese elements were designed, involving the knowledge of redox reactions, reversible reactions and coordination compounds, and the products were analyzed by UV-Vis spectrophotometer. The results showed that the unstable blue potassium manganate (V) was prepared from potassium manganate (VI) and manganese dioxide under strong alkaline conditions. Potassium permanganate and concentrated sulfuric acid under different conditions produced relatively stable red manganese trioxide and trivalent manganese ions, respectively, with rich color changes. This can provide experimental evidence for students to feel the transformation process of various oxidation states of manganese element, and also can effectively stimulate students' interest in learning.