What type of change is happening in Figure 1? When charcoal burns, it changes into other substances while producing heat and light. Burning is a chemical change. When a substance undergoes a chemical change, a chemical reaction is said to take place. In order to understand chemical reactions, you first must be able to describe them.

Figure 1  Burning is an example of a chemical reaction. When charcoal burns, the carbon in the charcoal reacts with oxygen in the air to produce carbon dioxide and heat.