Chemical Changes are also called Chemical Reactions. Possible clues to chemical change include a transfer of energy a change in color the production of a gas or the formation of a precipitate. Chemical Reactions Types Worksheet Awesome Types Of Chemical Reactions Chemical Reactions Reaction Types Education Subjects An industrial chemist studying this reaction fills a 250l tank with 45 mol of sulfur dioxide gas and 45 mol of oxygen gas at 30c. . Physical change and chemical change. The change in which the molecular composition is completely altered and a new product is formed is called a chemical change. Name four possible clues that a chemical change has taken place. Physical changes retain the fundamental identity of a substance without modifying its composition while chemical changes alter matter into another form having a set of different properties from the original substance. It reveals that chemical change cannot be