What happens during the experiment of iron and sulphur?

During the experiment involving iron and sulfur, the two elements are mixed together and then heated. Upon heating, they react chemically to form iron sulfide, a compound with different properties than the individual elements. This reaction demonstrates a chemical change, as the resulting iron sulfide cannot be separated back into iron and sulfur through physical means. The experiment illustrates principles of chemical reactions, including the conservation of mass and the formation of new substances.