Chemical properties are the properties of a substance that relate to its chemical composition and its ability to undergo chemical reactions. The odor of gasoline is a chemical property because it is a result of the chemical composition of gasoline. Gasoline is a mixture of hydrocarbons, and the different hydrocarbons that make up gasoline have different odors. The odor of gasoline is also affected by the presence of additives, such as detergents and octane boosters.