methane

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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 CnH2n+2.
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. It is less dense than air, melts at −184°C;, and boils at −161.4°C;. 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.
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; 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 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).
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 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
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). 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
References in periodicals archive ?
Gokhan Metan (a) *, Hayati Demiraslan (a), Leyla Gul Kaynar (b), Gokmen Zararsiz (c), Emine Alp (a), Bulent Eser (b)
Rio Las Piedras, 16 km al N de Metan (Salta, Metan) 25[grados]20'12"S 64[grados]56'04"W (16).
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Que no nos metan el dedo en la boca porque se lo vamos a morder
El dirigente opositor al gobierno llamo a los mas de 400 reunidos en la plaza de armas a cuidar el voto y a "que no se metan los Moreira", porque son buenos, senalo, para comprar el voto con dadivas como despensas, tinacos, pintura y ultimamente televisores.
Still, the Hollywood marketing and PR departments haven't caught up with the growth in the China market, says Metan Development prexy Larry Namer, who splits his time between Los Angeles and Beijing.
Sus amigos dicen que lo que mas detesta es que se metan en su vida privada Entre los criticos era habitual discutir las identidades y diferencias que se advierten al comparar las obras de Carrington y Varo.
Basta con reproducir una frase del presidente del club de la Universidad Catolica: "Estoy feliz porque hemos contratado un entrenador que hace que nuestros jugadores mojen la camiseta, corran, metan .
481 m, 15/XI/2004, Rueda Martin col; 12 machos; Rio Juramento, S25[grados]10'55",W65[grados]10'13", 790 m, 29/XI/2000, Cuezo Romero Manzo y Molineri cols, 2 machos; Metan, Rio Palo Largo, S25[grados]31'04", W65[grados]03'11", 1.
Primero, la prevencion, para evitar que mas muchachos se metan en pandillas.
venustus fueron capturados en la localidad de Rio de las Conchas (25[grados] 28' S, 61[grados] 01' W; 1027 m), Departamento Metan, provincia de Salta.
Los tenemos en nuestro road map y lo vemos como una excelente alternativa, porque permitira que en equipos del mismo tamano se metan mas procesadores".