Abstract:

In the Co²⁺ identification experiment, it was accidentally found that with an appropriate amount of SCN^- added into CoCl₂ solution, the solution presented reversible thermochromic phenomenon. Inspired by this phenomenon, the "flipped classroom" mode of experimental teaching of "doing first, teaching later, teaching determined by doing" was adopted accordingly based on the analysis and discussion of its thermochromic mechanism. Specifically, students do the experiment first and have questions during the experimental process, then the teacher demonstrates with students based on their questions, leading students to intuitive understanding of the thermochromic phenomenon and its influencing factors of some Co(Ⅱ) compounds or complexes. This article inspires students to use chemical principles and knowledge to explain and discuss the nature of thermochromic phenomenon, so as to deepen students' understanding of the structure, properties and concept of splitting energy of complexes. It also cultivates the students' ability of observation, analysis, judgment, induction, reasoning, summary, conclusion regular and "critical" thinking.

Key words: Co(Ⅱ) compounds, Thermochromism, Influencing factors, Discussion on thermochromic mechanism