As gas sits around, parts of it evaporate and can escape the fuel container–and we say “parts of it” because gasoline is a fairly complex substance.
Gasoline is made up of aliphatic and aromatic hydrocarbons–let’s call them open chains and closed rings. The light ends, technically known as short-chain aliphatic hydrocarbons, evaporate first, leaving behind the long-chain aliphatic and aromatic …
