The organic compounds known as alkanes are used primarily as fuels, but their derivatives can be found in paints, plastics, cosmetics, cleaners and pharmaceuticals. The simplest alkanes are propane, methane, butane and ethane. These are all highly combustible and form carbon dioxide and water as they burn, which makes them useful as clean fuels.
Alkanes are hydrocarbons and consist only of carbon and hydrogen. The number of carbon atoms within an alkane determines its use. Propane, butane and methane, for example, are cooking and heating fuels, and are also used to generate electricity in some countries. Butane is used in disposable cigarette lighters. Under relatively low pressure, butane and propane can be liquified, and are then known as LPG, or liquid petroleum gas. These two alkanes are also used in aerosol sprays as propellants. Some alkanes with a higher number of atoms form the greater part of aviation and diesel fuel. These alkanes, however, possess higher melting points, which can cause the fuels to become too thick to use in cold climates such as the polar regions. Kerosene and gasoline are made from combinations of alkanes.
Larger alkanes work well as lubricating oils. Their hydrophobic nature prevents water from reaching the surface of metal parts, and they also have anti-corrosive properties. Polypropylene and polyethylene, synthetic polymers with numerous applications, are alkanes containing extremely long chains of carbon atoms.