methane

/meth"ayn/; Brit. /mee"thayn/, n. Chem.

a colorless, odorless, flammable gas, CH₄, the main constituent of marsh gas and the firedamp of coal mines, obtained commercially from natural gas: the first member of the methane, or alkane, series of hydrocarbons.

[1865-70; METH- + -ANE]

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or marsh gas

Organic compound, chemical formula CH₄, colourless, odourless gas that occurs in natural gas (called firedamp in coal mines) and from bacterial decomposition of vegetation in the absence of oxygen (including in the rumens of cattle and other ruminants and in the gut of termites).

The simplest member of the paraffin hydrocarbons, methane burns readily, forming carbon dioxide and water if supplied with enough oxygen for complete combustion or carbon monoxide if the oxygen is insufficient. Mixtures of 5–14% methane in air are explosive and have caused many mine disasters. The chief source of methane is natural gas, but it can also be produced from coal. Abundant, cheap, and clean, methane is used widely as a fuel in homes, commercial establishments, and factories; as a safety measure, it is mixed with trace amounts of an odorant to allow its detection. It is also a raw material for many industrial materials, including fertilizers, explosives, chloroform, carbon tetrachloride, and carbon black, and is the principal source of methanol.

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▪ chemical compound

also called  marsh gas,  

 colourless, odourless gas that occurs abundantly in nature as the chief constituent of natural gas, as a component of firedamp in coal mines, and as a product of the anaerobic bacterial decomposition of vegetable matter under water (hence its alternate name, marsh gas). Methane also is produced industrially by the destructive distillation of bituminous coal in the manufacture of coal gas and coke-oven gas. The decomposition of sludge by anaerobic bacteria in sewage-treatment processes also produces a gas rich in methane.

 Methane is the simplest member of the paraffin series of hydrocarbons. Its chemical formula is CH₄. It is lighter than air, having a specific gravity of 0.554. It is only slightly soluble in water. It burns readily in air, forming carbon dioxide and water vapour; the flame is pale, slightly luminous, and very hot. The boiling point of methane is -162.0° C (-259.6° F) and the melting point is -182.5° C (-296.5° F). Methane in general is very stable, but mixtures of methane and air, with the methane content between 5 and 14 percent by volume, are explosive. Explosions of such mixtures have been frequent in coal mines and collieries and have been the cause of many mine disasters.

      The chief source of methane is natural gas, which contains from 50 to 90 percent methane, depending on the source. Methane produced by the destructive distillation of bituminous coal and by coal carbonization is important in locations where natural gas is not plentiful.

      Since commercial natural gas is composed largely of methane, their uses may for all practical purposes be considered identical. Because of its abundance, low cost, ease of handling, and cleanliness, such gas is widely used as a fuel in homes, commercial establishments, and factories.

      Methane is an important source of hydrogen and some organic chemicals. Methane reacts with steam at high temperatures to yield carbon monoxide and hydrogen; the latter is used in the manufacture of ammonia for fertilizers and explosives. Other valuable chemicals derived from methane include methanol, chloroform, carbon tetrachloride, and nitromethane. The incomplete combustion of methane yields carbon black, which is widely used as a reinforcing agent in rubber used for automobile tires.

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