Butane is a colorless, odorless, very flammable gas derived, along with other gases, from raw natural gas. Though it is a gaseous substance, butane can easily liquefy or turn to liquid form when compressed. Butane is composed purely of hydrogen and carbon atoms, hence it is called a hydrocarbon—a compound of hydrogen and carbon. Its chemical formula is C4H10, which means that butane has 4 carbon atoms attached to 10 hydrogen atoms.
The arrangement and attachment of the hydrogen atoms to the carbon atoms can be either in a straight chain or in a branched chain. Butane whose structure is in a straight chain is called n-butane (also called normal butane or unbranched butane). Used as a generic term, “butane” can refer to n-butane or its relative, isobutane.
Another form of butane exists as an isomer of n-butane. Since it is an isomer of n-butane, it still has 4 carbon atoms and 10 hydrogen atoms, but the arrangement of the atoms are in a branched chain. Butane whose structure appears like a branched chain is called isobutane or i-butane, properly called methylpropane.
The International Union of Pure and Applied Chemistry (IUPAC) strictly uses “butane” to refer only to n-butane and “methylpropane” to refer only to i-butane.
Being extremely flammable, butane is used as fuel. It is the common fuel used in cigarette lighters. Butane is liquefied by compressing butane gas and stored in the fuel reservoir of the lighter. When a valve is opened, the liquid butane decompresses and quickly turns to gas. The decompressed butane escapes the reservoir in the form of a stream of colorless gas and is ignited, thereby producing a flame.
Butane is also used in liquid propane gas (more commonly known as LPG or liquefied petroleum gas), which combines butane and propane. LPG is also used as fuel. It is often sold as bottled gas, which is popular among campers and those who love outdoor grill parties. LPG or bottled gas can fuel camping stoves and gas-powered grills. Although propane produces more heat than butane and is more efficient in combustion, butane has a characteristic that makes it a favorite: it liquefies easily, and therefore, makes containment easy.
Unlike some other flammable gases derived from natural gas, butane produces only carbon dioxide as a byproduct when burned.
Butane is also used as a refrigerant. Isobutane (i-butane) or methylpropane, for example, is used to replace freon as a refrigerant in freezers and refrigerators. Using butane as refrigerant is more environment- and earth-friendly compared to using halomethanes that are known to damage the earth’s ozone layer.
Besides its use as fuel and refrigerant, butane is also used as aerosol propellant for aerosol insecticides, deodorants, or paint. Liquefied butane is mixed with liquid insecticide, deodorant, or paint and is stored in a can or bottle. When the control valve is opened, the liquid mix is expelled or propelled as a mist. Butane evaporates or turns to gas quickly as soon as it leaves the container, therefore leaving the payload (which can be the insecticide, deodorant, or paint) suspended as very tiny droplets.