The responsible chemistry teacher in four-star high school still tries his best to show the students the demonstration experiment, or wants to arouse the students' enthusiasm for learning chemistry. Although it has little effect, it is usually poured directly into the sewer, and the harm and pollution caused by it can be completely ignored. Don't ignore the big things. The pollution caused by any factory and the garbage produced by any family are more harmful to the environment than one or two chemical experiments done by teachers.