The main factor that distinguishes one category form the other is whether or not a particular change results in the production of a new substance. Physical changes are those changes that do not result in the production of a new substance. If you melt a block of ice, you still have H 2 O at the end of the change. If you break a bottle, you still have glass. Painting a piece of wood will not make it stop being wood.
Chemical changes are changes that result in the production of another substance.
When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon. When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide. Excellent Lessons on the Whole Chapter Copyright 2001 Fordham Preparatory School, All Rights Reserved.