The burning of gasoline is a chemical change, while the evaporation of gasoline is a physical change.
When gasoline burns, it undergoes a chemical reaction with oxygen in the air, producing carbon dioxide and water. This process involves the breaking and forming of bonds between atoms, resulting in new substances. The properties of gasoline are fundamentally altered; for instance, the heat energy released during combustion is used to power engines, and the gaseous products cannot be transformed back into gasoline.
On the other hand, when gasoline evaporates, it simply changes from a liquid state to a vapor without altering its chemical structure. The molecules of gasoline gain enough energy to escape into the air, but they remain as gasoline molecules, just in a different phase. This process is reversible—if the vapor cools down, it can condense back into liquid gasoline.
In summary, burning gasoline is a chemical change because it produces new substances, while evaporating gasoline is a physical change as it merely alters its state without changing its chemical composition.