ਮੀਥੇਨ: ਰੀਵਿਜ਼ਨਾਂ ਵਿਚ ਫ਼ਰਕ

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Methane is the major component of natural gas, about 87% by volume. At [[room temperature]] and [[standard pressure]], methane is a colorless, odorless gas; the smell characteristic of natural gas as used in homes is an artificial safety measure caused by the addition of an [[odorant]], often [[methanethiol]] or [[ethanethiol]]. Methane has a boiling point of −161 °[[Celsius|C]] at a pressure of one [[Atmosphere (unit)|atmosphere]]. As a gas it is [[flammable]] only over a narrow range of concentrations (5–15%) in air. Liquid methane does not burn unless subjected to high pressure (normally 4–5 atmospheres).

 

If methane and X₂ are used in equimolar quantities, CH₂X₂, CHX₃, and even CX₄ are formed. Using a large excess of CH₄ reduces the production of CH₂X₂, CHX₃, CX₄, and thus more CH₃X is formed.

 

===Fuel===

:''For more on the use of methane as a fuel, see [[natural gas]]''

Recently methane emitted from coal mines has been successfully converted to electricity.<ref>[http://www.megtec.com/news_article.php?news_id=42 A Global First: Coal Mine Turns Greenhouse Gas into Green Energy]</ref>

 

Methane is used in industrial chemical processes and may be transported as a refrigerated liquid (liquefied natural gas, or [[LNG]]). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of the cold gas, the gas at ambient temperature is lighter than air. [[Pipeline transport|Gas pipeline]]s distribute large amounts of natural gas, of which methane is the principal component.

 

Less significant methane-derived chemicals include [[acetylene]], prepared by passing methane through an [[electric arc]], and the chloromethanes ([[chloromethane]], [[dichloromethane]], [[chloroform]], and [[carbon tetrachloride]]), produced by reacting methane with [[chlorine]] gas. However, the use of these chemicals is declining. Acetylene is replaced by less costly substitutes, and the use of chloromethanes is diminishing due to health and environmental concerns.

 

The major source of methane is extraction from geological deposits known as [[natural gas fields]]. It is associated with other [[hydrocarbon]] fuels and sometimes accompanied by [[helium]] and [[nitrogen]]. The gas at shallow levels (low pressure) is formed by [[anaerobic organism|anaerobic]] [[decay]] of [[organic matter]] and reworked methane from deep under the Earth's surface. In general, sediments buried deeper and at higher temperatures than those which give [[Petroleum|oil]] generate natural gas. Methane is also produced in considerable quantities from the decaying organic wastes of [[solid waste]] [[landfill]]s.

 

Apart from gas fields, an alternative method of obtaining methane is via [[biogas]] generated by the [[fermentation (biochemistry)|fermentation]] of organic matter including [[manure]], wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock, under anaerobic conditions. Methane hydrates/clathrates (ice-like combinations of methane and water on the sea floor, found in vast quantities) are a potential future source of methane. Cattle belch methane accounts for 16% of the world's annual methane emissions to the atmosphere.<ref>Miller, G. Tyler. ''Sustaining the Earth: An Integrated Approach''. U.S.A.: Thomson Advantage Books, 2007. 160.</ref> The livestock sector in general (primarily cattle, chickens, and pigs) produces 37% of all human-induced methane.<ref>{{cite web |url=http://www.fao.org/docrep/010/a0701e/a0701e00.HTM

|title=Livestock’s Long Shadow–Environmental Issues and Options|accessdate=2009-10-27}}</ref> Early research has found a number of medical treatments and dietary adjustments that help slightly limit the production of methane in [[ruminants]].<ref>[http://news.nationalgeographic.com/news/2002/05/0509_020509_belch.html New Zealand Tries to Cap Gaseous Sheep Burps]</ref><ref>[http://www.alternet.org/story/72339/ Research on use of bacteria from the stomach lining of kangaroos (who don't emit methane) to reduce methane in cattle]</ref>

Scientific experiments have given variable results in determining whether plants are a source of methane emissions.<ref>{{cite journal |author=Hamilton JT, McRoberts WC, Keppler F, Kalin RM, Harper DB |title=Chloride methylation by plant pectin: an efficient environmentally significant process |journal=Science (journal) |volume=301 |issue=5630 |pages=206–9 |year=2003 |month=July |pmid=12855805 |doi=10.1126/science.1085036 |url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=12855805}}</ref><ref>[http://sciencenow.sciencemag.org/cgi/content/full/2009/114/1 "Methane Emissions? Don't Blame Plants"], ScienceNOW, 14 January 2009</ref><ref>[http://environment.newscientist.com/article/mg19626322.900-plants-do-emit-methane-after-all.html Plants do emit methane after all], ''[[New Scientist]]'', 2 December 2007</ref>

 

{{Main|Atmospheric methane}}

{{Unreferenced|date=January 2010}}

In prehistoric times, large methane excursions have been linked with dramatic shifts in the Earth's climate, notably during the [[Paleocene-Eocene thermal maximum]] and during the [[Permian-Triassic extinction event]], which was the worst ever [[mass extinction]].{{Dubious|February 2010|date=February 2010}}

 

Methane has been detected or is believed to exist in several locations of the [[solar system]]. It is believed to have been created by [[Abiotic components|abiotic]] processes, with the possible exception of [[Life on Mars|Mars]].

 

*[[Interstellar cloud]]s<ref>{{cite journal|author=J. H. Lacy, J. S. Carr, N. J. Evans, II, F. Baas, J. M. Achtermann, J. F. Arens|title=Discovery of interstellar methane&nbsp;— Observations of gaseous and solid CH4 absorption toward young stars in molecular clouds|journal=Astrophysical Journal|year=1991|volume=376|pages=556–560|url=http://adsabs.harvard.edu/abs/1991ApJ...376..556L|doi = 10.1086/170304+|pmid=19122700|last1=Rai|first1=VN|last2=Yueh|first2=FY|last3=Singh|first3=JP|issue=31|doi_brokendate=2009-10-03}}</ref>

 

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*[[2007 Zasyadko mine disaster]]