Energy development, national defense and military industry, scientific research and all walks of life of the national economy, but it is difficult to give an accurate definition of what is "chemical reagent" and what it contains. Early chemical reagents only refer to "pure chemicals used in chemical analysis and chemical tests to determine the composition or composition of substances". Later, it was expanded to "chemicals used to realize chemical reactions", and the "chemical reagents" referred to by "chemicals" had already gone beyond this category. Some people think that "chemicals used in scientific experiments" can be called "chemical reagents". A more comprehensive definition of chemical reagents can be: compounds or simple substances of various purity levels used in chemical tests, chemical analysis, chemical research and other tests.