Abstract The magenta solution used to identify sulfur dioxide gas is divided into two kinds: acid magenta and alkaline magenta. In this article, the mechanism of fading reaction and differences between acid magenta and alkaline magenta while reacting with sulfur dioxide or acid or base were discussed by optimizing the experimental conditions through a green and improved experimental equipment integrating demonstration and comparative function. Moreover, a simple way to identify acid magenta and alkaline magenta had also been put forward.
