Gasoline

Gasoline, also called petrol, is a flammable liquid fuel primarily used to power internal combustion engines, such as those in cars, motorcycles, and small machinery.  It’s derived from crude oil through a refining process that involves distillation, cracking, and other chemical treatments to separate and enhance its components.  Chemically, gasoline is a mixture of hydrocarbons, compounds made of hydrogen and carbon atoms, typically containing 5 to 12 carbon atoms per molecule, with common ones like octane (\(C_8H_{18}\)) being key for performance. 

It’s stored and sold in various grades (like 87, 89, or 91 octane in the U.S.), which indicate its resistance to knocking—premature combustion in an engine.  Additives like ethanol (often up to 10% in many blends) are mixed in to boost octane, improve combustion, or meet environmental regulations.  Gasoline’s energy content is about 33.7 megajoules per liter (or 120 MJ per gallon), making it a dense, portable energy source, though it’s less efficient than diesel in some applications.