A chemical change occurs when the chemical composition of a substance changes, resulting in the formation of one or more new substances. In this case, glucose, which is a sugar, is broken down by yeast into ethanol, or alcohol, and carbon dioxide. This reaction is known as fermentation.
The chemical equation for this reaction is:
$$C_6H_{12}O_6 \rightarrow 2 C_2H_5OH + 2 CO_2$$
Glucose reacts with water to produce ethanol and carbon dioxide. The carbon atoms in glucose are rearranged to form ethanol, while the oxygen atoms combine with hydrogen atoms from water to form carbon dioxide.
The chemical change that occurs during fermentation is irreversible, meaning that the ethanol and carbon dioxide produced cannot be converted back into glucose.
