Argon
Argon | ||||||||||||||||||||||||||||||||||||||||||||||
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Pronunciation | /ˈɑːrɡɒn/ | |||||||||||||||||||||||||||||||||||||||||||||
Appearance | colorless gas exhibiting a lilac/violet glow when placed in an electric field | |||||||||||||||||||||||||||||||||||||||||||||
Standard atomic weight Ar°(Ar) | ||||||||||||||||||||||||||||||||||||||||||||||
Argon in the periodic table | ||||||||||||||||||||||||||||||||||||||||||||||
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kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||
Heat of vaporization | 6.53 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||
Molar heat capacity | 20.85[4] J/(mol·K) | |||||||||||||||||||||||||||||||||||||||||||||
Vapor pressure
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Atomic properties | ||||||||||||||||||||||||||||||||||||||||||||||
Lord Rayleigh and William Ramsay (1894) | ||||||||||||||||||||||||||||||||||||||||||||||
Isotopes of argon | ||||||||||||||||||||||||||||||||||||||||||||||
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Argon is a
Nearly all argon in Earth's atmosphere is
The name "argon" is derived from the Greek word ἀργόν, neuter singular form of ἀργός meaning 'lazy' or 'inactive', as a reference to the fact that the element undergoes almost no chemical reactions. The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements. Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.
Argon is extracted industrially by the
Characteristics
Argon has approximately the same solubility in water as oxygen and is 2.5 times more soluble in water than nitrogen. Argon is colorless, odorless, nonflammable and nontoxic as a solid, liquid or gas.[10] Argon is chemically inert under most conditions and forms no confirmed stable compounds at room temperature.
Although argon is a
History
Argon (Greek ἀργόν, neuter singular form of ἀργός meaning "lazy" or "inactive") is named in reference to its chemical inactivity. This chemical property of this first noble gas to be discovered impressed the namers.[15][16] An unreactive gas was suspected to be a component of air by Henry Cavendish in 1785.[17]
Argon was first isolated from air in 1894 by
Before isolating the gas, they had determined that nitrogen produced from chemical compounds was 0.5% lighter than nitrogen from the atmosphere. The difference was slight, but it was important enough to attract their attention for many months. They concluded that there was another gas in the air mixed in with the nitrogen.[21] Argon was also encountered in 1882 through independent research of H. F. Newall and W. N. Hartley.[22] Each observed new lines in the emission spectrum of air that did not match known elements.
Until 1957, the symbol for argon was "A", but now it is "Ar".[23]
Occurrence
Argon constitutes 0.934% by volume and 1.288% by mass of
Isotopes
The main isotopes of argon found on Earth are 40
Ar (99.6%), 36
Ar (0.34%), and 38
Ar (0.06%). Naturally occurring 40
K, with a half-life of 1.25×109 years, decays to stable 40
Ar (11.2%) by electron capture or positron emission, and also to stable 40
Ca (88.8%) by beta decay. These properties and ratios are used to determine the age of rocks by K–Ar dating.[26][27]
In Earth's atmosphere, 39
Ar is made by
Between locations in the
The atmospheres of Mars, Mercury and Titan (the largest moon of Saturn) contain argon, predominantly as 40
Ar, and its content may be as high as 1.93% (Mars).[30]
The predominance of
Ar is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was puzzling when argon was discovered. Mendeleev positioned the elements on his periodic table in order of atomic weight, but the inertness of argon suggested a placement before the reactive alkali metal. Henry Moseley later solved this problem by showing that the periodic table is actually arranged in order of atomic number (see History of the periodic table
Compounds
Argon's complete octet of
Solid argon hydride (Ar(H2)2) has the same crystal structure as the MgZn2 Laves phase. It forms at pressures between 4.3 and 220 GPa, though Raman measurements suggest that the H2 molecules in Ar(H2)2 dissociate above 175 GPa.[37]
Production
Argon is extracted industrially by the
Applications
Argon has several desirable properties:
- Argon is a chemically inert gas.
- Argon is the cheapest alternative when nitrogen is not sufficiently inert.
- Argon has low thermal conductivity.
- Argon has electronic properties (ionization and/or the emission spectrum) desirable for some applications.
Other
Industrial processes
Argon is used in some high-temperature industrial processes where ordinarily non-reactive substances become reactive. For example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.
For some of these processes, the presence of nitrogen or oxygen gases might cause defects within the material. Argon is used in some types of arc welding such as gas metal arc welding and gas tungsten arc welding, as well as in the processing of titanium and other reactive elements. An argon atmosphere is also used for growing crystals of silicon and germanium.
Argon is used in the poultry industry to asphyxiate birds, either for mass culling following disease outbreaks, or as a means of slaughter more humane than electric stunning. Argon is denser than air and displaces oxygen close to the ground during inert gas asphyxiation.[39][40] Its non-reactive nature makes it suitable in a food product, and since it replaces oxygen within the dead bird, argon also enhances shelf life.[41]
Argon is sometimes used for extinguishing fires where valuable equipment may be damaged by water or foam.[42]
Scientific research
Liquid argon is used as the target for neutrino experiments and direct
At Linköping University, Sweden, the inert gas is being utilized in a vacuum chamber in which plasma is introduced to ionize metallic films.[45] This process results in a film usable for manufacturing computer processors. The new process would eliminate the need for chemical baths and use of expensive, dangerous and rare materials.
Preservative
Argon is used to displace oxygen- and moisture-containing air in packaging material to extend the shelf-lives of the contents (argon has the
In winemaking, argon is used in a variety of activities to provide a barrier against oxygen at the liquid surface, which can spoil wine by fueling both microbial metabolism (as with acetic acid bacteria) and standard redox chemistry.
Argon is sometimes used as the propellant in aerosol cans.
Argon is also used as a preservative for such products as varnish, polyurethane, and paint, by displacing air to prepare a container for storage.[47]
Since 2002, the American
Laboratory equipment
Argon may be used as the inert gas within Schlenk lines and gloveboxes. Argon is preferred to less expensive nitrogen in cases where nitrogen may react with the reagents or apparatus.
Argon may be used as the carrier gas in
Medical use
Blue
Argon has also been used experimentally to replace nitrogen in the breathing or decompression mix known as
Lighting
Miscellaneous uses
Argon is used for thermal insulation in energy-efficient windows.[51] Argon is also used in technical scuba diving to inflate a dry suit because it is inert and has low thermal conductivity.[52]
Argon is used as a propellant in the development of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). Compressed argon gas is allowed to expand, to cool the seeker heads of some versions of the AIM-9 Sidewinder missile and other missiles that use cooled thermal seeker heads. The gas is stored at high pressure.[53]
Argon-39, with a half-life of 269 years, has been used for a number of applications, primarily
Argon has been used by athletes as a doping agent to simulate hypoxic conditions. In 2014, the World Anti-Doping Agency (WADA) added argon and xenon to the list of prohibited substances and methods, although at this time there is no reliable test for abuse.[54]
Safety
Although argon is non-toxic, it is 38% more dense than air and therefore considered a dangerous asphyxiant in closed areas. It is difficult to detect because it is colorless, odorless, and tasteless. A 1994 incident, in which a man was asphyxiated after entering an argon-filled section of oil pipe under construction in Alaska, highlights the dangers of argon tank leakage in confined spaces and emphasizes the need for proper use, storage and handling.[55]
See also
- Industrial gas
- Oxygen–argon ratio, a ratio of two physically similar gases, which has importance in various sectors.
References
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- ^ In older versions of the periodic table, the noble gases were identified as Group VIIIA or as Group 0. See Group (periodic table).
- ^ "Material Safety Data Sheet Gaseous Argon". UIGI.com. Universal Industrial Gases, Inc. Retrieved 14 October 2013.
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- ^ a b Perkins, S. (26 August 2000). "HArF! Argon's not so noble after all – researchers make argon fluorohydride". Science News.
- ^ Belosludov, V. R.; Subbotin, O. S.; Krupskii, D. S.; Prokuda, O. V.; et al. (2006). "Microscopic model of clathrate compounds". .
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Cohen, A.; Lundell, J.; Gerber, R. B. (2003). "First compounds with argon–carbon and argon–silicon chemical bonds". S2CID 95850840.
- ^ Hiebert, E. N. (1963). "In Noble-Gas Compounds". In Hyman, H. H. (ed.). Historical Remarks on the Discovery of Argon: The First Noble Gas. University of Chicago Press. pp. 3–20.
- ^ Travers, M. W. (1928). The Discovery of the Rare Gases. Edward Arnold & Co. pp. 1–7.
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JSTOR 115394.
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Lord Rayleigh; Ramsay, William (1895). "VI. Argon: A New Constituent of the Atmosphere". Philosophical Transactions of the Royal Society A. 186: 187–241. JSTOR 90645.
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Ramsay, W. (1904). "Nobel Lecture". The Nobel Foundation.
- ^ "About Argon, the Inert; The New Element Supposedly Found in the Atmosphere". The New York Times. 3 March 1895. Retrieved 1 February 2009.
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- ^ Holden, N. E. (12 March 2004). "History of the Origin of the Chemical Elements and Their Discoverers". National Nuclear Data Center.
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"Argon, Ar". Etacude.com. Archived from the original on 7 October 2008. Retrieved 8 March 2007.
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Barlow, M. J.; et al. (2013). "Detection of a Noble Gas Molecular Ion, 36ArH+, in the Crab Nebula". S2CID 37578581.
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- ^ Fletcher, D. L. "Slaughter Technology" (PDF). Symposium: Recent Advances in Poultry Slaughter Technology. Archived from the original (PDF) on 24 July 2011. Retrieved 1 January 2010.
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Gastler, Dan; Kearns, Ed; Hime, Andrew; Stonehill, Laura C.; et al. (2012). "Measurement of scintillation efficiency for nuclear recoils in liquid argon". Physical Review C. 85 (6): 065811. S2CID 6876533.
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Xu, J.; Calaprice, F.; Galbiati, C.; Goretti, A.; Guray, G.; et al. (26 April 2012). "A Study of the Residual 39
Ar Content in Argon from Underground Sources". Astroparticle Physics. 66 (2015): 53–60.S2CID 117711599. - ^ "Plasma electrons can be used to produce metallic films". Phys.org. 7 May 2020. Retrieved 8 May 2020.
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- ^ "Fatal Gas Embolism Caused by Overpressurization during Laparoscopic Use of Argon Enhanced Coagulation". MDSR. 24 June 1994.
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Pilmanis Andrew A.; Balldin U. I.; Webb James T.; Krause K. M. (2003). "Staged decompression to 3.5 psi using argon–oxygen and 100% oxygen breathing mixtures". Aviation, Space, and Environmental Medicine. 74 (12): 1243–1250. PMID 14692466.
- ^ "Energy-Efficient Windows". FineHomebuilding.com. February 1998. Retrieved 1 August 2009.
- ^ Nuckols M. L.; Giblo J.; Wood-Putnam J. L. (15–18 September 2008). "Thermal Characteristics of Diving Garments When Using Argon as a Suit Inflation Gas". Proceedings of the Oceans 08 MTS/IEEE Quebec, Canada Meeting. Archived from the original on 21 July 2009. Retrieved 2 March 2009.
{{cite journal}}
: CS1 maint: unfit URL (link) - ^ "Description of Aim-9 Operation". planken.org. Archived from the original on 22 December 2008. Retrieved 1 February 2009.
- ^ "WADA amends Section S.2.1 of 2014 Prohibited List". 31 August 2014. Archived from the original on 27 April 2021. Retrieved 1 September 2014.
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Alaska FACE Investigation 94AK012 (23 June 1994). "Welder's Helper Asphyxiated in Argon-Inerted Pipe – Alaska (FACE AK-94-012)". State of Alaska Department of Public Health. Retrieved 29 January 2011.
{{cite web}}
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Further reading
- Brown, T. L.; Bursten, B. E.; LeMay, H. E. (2006). J. Challice; N. Folchetti (eds.). Chemistry: The Central Science (10th ed.). ISBN 978-0-13-109686-8.
- Lide, D. R. (2005). "Properties of the Elements and Inorganic Compounds; Melting, boiling, triple, and critical temperatures of the elements". ISBN 978-0-8493-0486-6. On triple point pressure at 69 kPa.
- Preston-Thomas, H. (1990). "The International Temperature Scale of 1990 (ITS-90)". S2CID 250785635. On triple point pressure at 83.8058 K.
External links
- Argon at The Periodic Table of Videos(University of Nottingham)
- USGS Periodic Table – Argon
- Diving applications: Why Argon?