Educational experiments on diffusion for classroom and optional training sessions in chemistry and physics

The results of a didactic study of an educational experiment on diffusion in gases and liquids for classroom and optional training sessions in chemistry and physics are presented. The object of the research are experiments on the diffusion of ammonia in air and in an aqueous solution of phenolphthalein, intended for lessons and optional project activities in the study of physics and chemistry at school. Optimal experimental conditions are determined, educational devices are described, elements of the physical theory of diffusion and the chemical theory of indicators are considered, and quantitative experimental results are presented.