A generalizable gradient popular science experiment design: based on the principle of acid-base discoloration of natural lac red pigment

In order to design a green, safe and generalizable gradient science popularization experiment, this study takes the natural pigment lac red pigment as the research object. Firstly, the lac red pigment was extracted from the Chinese medicinal material comfrey mushroom using the common reagents in the laboratory and substances in the family, which named laboratory method and home method, respectively. Secondly, the discoloration principle of lac red pigment extracted by two methods was verified. Finally, the science popularization was tried for the public of different ages. The laboratory method was to effectively extract lac red pigment from lac by salting out method, and preliminarily verified that the discoloration of lac red pigment was due to the acid-base ionization balance of lac red pigment. And the discoloration phenomenon of lac red pigment solution at different pH is obvious, and when the pH increases from low to high, the color of the solution changes to yellow, orange-yellow, orange, orange-red, light purple to purple. It can be used as an acid-base indicator with strong dyeing and coloring ability. Based on laboratory method, the home method used common substances with similar physical and chemical properties to replace the corresponding reagents, extracts lac red pigment from Chinese medicinal material comfrey, and verifies the discoloration reaction of lac red pigment. Therefore, the use of natural lac red pigment acid-base discoloration principle and dyeing agent can achieve gradient science popularization experiments for different levels of audiences.