An important concept in chemistry classes is the chemical reaction or the chemical process. A chemical process occurs when the starting materials forms new substances with different properties. Chemical processes coupled with energy conversions are called a chemical reactions. In this experiment students study the behavior of copper in sulfur vapor, a piece of sulfur is heated and a picece of copper is held in the vapor in a test tube. The copper and sulfur combine to a new substance, which can be recognized from the change in color, density and other properties.