methane

(mĕth`ān), CH₄, colorless, odorless, gaseous saturated hydrocarbon; the simplest alkanealkane
, any of a group of aliphatic hydrocarbons whose molecules contain only single bonds (see chemical bond). Alkanes have the general chemical formula C_nH_2n+2.
..... Click the link for more information. . It is less dense than air, melts at −184&degC;, and boils at −161.4&degC;. It is combustible and can form explosive mixtures with air. Methane occurs naturally as the principal component of natural gasnatural gas,
natural mixture of gaseous hydrocarbons found issuing from the ground or obtained from specially driven wells. The composition of natural gas varies in different localities.
..... Click the link for more information. ; it is formed by the decomposition of plant and animal matter. When this decomposition occurs underwater in swamps and marshes, marsh gas is released. The firedamp of coal mines is chiefly methane. In the atmosphere methane is a significant greenhouse gas, helping to trap infrared radiationinfrared radiation,
electromagnetic radiation having a wavelength in the range from c.75 × 10⁻⁶ cm to c.100,000 × 10⁻⁶ cm (0.000075–0.1 cm).
..... Click the link for more information. and warm the earth (see also global warmingglobal warming,
the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. Global warming and its effects, such as more intense summer and winter storms, are also referred to as climate
..... Click the link for more information. ). Methane, in the form of icelike methane hydrate (composed of methane and frozen water), also is stored in seabed sediments at ocean depths where sufficiently low temperatures and high pressures prevail.

Methane can be prepared in the laboratory by heating sodium acetate with sodium hydroxide, by the reaction of aluminum carbide with water, by the direct combination of carbon and hydrogen, or by the destructive distillation of coal or wood. As natural gas, methane is widely used for fuel. It is also used for carbonizing steel. It is unaffected by many common chemical reagents but reacts violently with chlorine or fluorine in the presence of light and is therefore important as a starting material for the synthesis of solvents, e.g., methylene chloride, chloroform, and carbon tetrachloride, and of some of the Freon refrigerants.

Methane

(CH4)A greenhouse gas that is emitted during the production and transport of coal, natural gas, and oil or from the decomposition of organic wastes in municipal solid waste landfills and the raising of livestock. Although CO₂ is more prevalent in the atmosphere, methane is over 20 times more effective in trapping heat than CO₂ over a 100-year period.

Methane

(also marsh gas or firedamp), CH₄, the first member of the homologous series of saturated hydrocarbons; a colorless, odorless gas. Boiling point, — 164.5°C, melting point, — 182.5°C; density (relative to air), 0.554 at 20°C. It burns with a virtually colorless flame. Heat of combustion, 50.08 megajoules per kg (11,954 kcal/kg).

Methane is the main component of natural gas (77–99 percent by volume), casinghead gas (31–90 percent), and mine gas (34–40 percent). It is also found in volcanic gases and is produced continuously by the decomposition of organic matter under the action of methane-forming bacteria with a limited supply of air (marsh gas and gases in irrigated fields). The atmospheres of Saturn and Jupiter are composed largely of methane. Methane is produced during thermal refining of petroleum and petroleum products (10–57 percent by volume), as well as during the coking and hydrogenation of coal (24-34 percent). Laboratory methods of methane preparation include fusion of sodium acetate with an alkali and the action of water on methyl magnesium iodide or aluminum carbide.

Methane forms explosive mixtures with air. Methane evolved in underground workings during the mining of mineral deposits, as well as in coal-washing and briquetting plants and sorting installations, is the most dangerous. For example, at a methane content of 5–6 percent in air, methane will burn near a heat source (flash point, 650°-750°C); it will explode when the content is 5–6 to 14–16 percent. If the methane content is more than about 16 percent, the gas may burn if there is an oxygen flow from an external source; a reduction in methane concentration at this stage can lead to an explosion. In addition, a substantial increase in the methane concentration in air induces suffocation (for example, 43 percent methane corresponds to 12 percent O₂).

Explosive combustion propagates at a rate of 500–700 m/sec; the gas pressure upon explosion in a closed space is 1 meganewton per sq m.

After initial contact with the heat source, the combustion of methane is somewhat delayed. This property is the basis for the manufacture of permissible explosives and explosion-proof electrical equipment. Gas conditions are implemented in areas that are hazardous because of the presence of methane (particularly coal mines).

Methane is the most thermally stable saturated hydrocarbon. It is widely used as a household and industrial fuel, and also as an industrial raw material. For example, methyl chloride, methylene chloride, chloroform, and carbon tetrachloride are all prepared by chlorination of methane. Partial combustion of methane yields carbon black, and catalytic oxidation produces formaldehyde. Carbon disulfide is formed by the reaction of methane and sulfur. Important industrial methods used in the preparation of acetylene include thermal-oxidation cracking and electrocracking of methane. The industrial manufacture of hydrocyanic acid is based on catalytic oxidation of a methaneammonia mixture. Methane is used as a hydrogen source in the preparation of ammonia, as well as in the manufacture of water gas (synthesis gas) according to the formula CH₄ + H₂O → CO + 3H₂; water gas is used in the industrial synthesis of hydrocarbons, alcohols, and aldehydes. Nitromethane is an important methane derivative.

methane

[′meth‚ān] (organic chemistry) CH₄ A colorless, odorless, and tasteless gas, lighter than air and reacting violently with chlorine and bromine in sunlight, a chief component of natural gas; used as a source of methanol, acetylene, and carbon monoxide. Also known as methyl hydride.

methane

a colourless odourless flammable gas, the simplest alkane and the main constituent of natural gas: used as a fuel. Formula: CH₄

methane

[meth´ān] an inflammable, explosive gas from decomposition of organic matter.

meth·ane

(meth'ān), CH₄; an odorless gas produced by the decomposition of organic matter; explosive when mixed with 7 or 8 volumes of air, constituting then the firedamp in coal mines. Synonym(s): marsh gas

methane

(mĕth′ān′)n. An odorless, colorless, flammable gas, CH₄, the major constituent of natural gas, that is used as a fuel and is an important source of hydrogen and a wide variety of organic compounds.

methane

A simple organic compound—CH4—which is a gas at room temperature.
Pronunciation
Medspeak-UK: pronounced, MEE thane
Medspeak-US: pronounced, MEH thane

METHANE

One of two mnemonics (the other is CHALET) used in the context of a major incident (mass disaster) for the information that the first ambulance staff to arrive on the scene should relay to the Emergency Operations Centre.
METHANE
Major incident declared (or hospitals to stand by).
Exact location of the incident, with map references if possible.
Type of incident, with brief details of types and numbers of vehicles, trains, buildings, aircraft, etc.
Hazards, present and potential.
Access routes and suitable provisional rendezvous points.
Numbers of approximate priority 1, 2 and 3 patients, dead and injured.
Emergency services present and required including local authorities.

meth·ane

(meth'ān) An odorless gas produced by the decomposition of organic matter; explosive when mixed with 7 or 8 volumes of air, constituting in such cases the firedamp in coal mines.

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Words related to methane

noun a colorless odorless gas used as a fuel

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