Krypton: Difference between revisions
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Krypton is considered to be a non-toxic [[asphyxiant gas|asphyxiant]].<ref>[http://pt.chemicalstore.com/Kr%20-%20Krypton.html Properties of Krypton]</ref> Krypton has a [[narcotic]] potency seven times greater than air, so breathing a gas containing 50% krypton and 50% air would cause narcosis similar to breathing air at four times atmospheric pressure. This would be comparable to scuba diving at a depth of {{convert|30|m|ft|abbr=on|sigfig=1}} (see [[nitrogen narcosis]]) and potentially could affect anyone breathing it. Nevertheless, that mixture would contain only 10% oxygen and [[Hypoxia (medical)|hypoxia]] would be a greater concern. |
Krypton is considered to be a non-toxic [[asphyxiant gas|asphyxiant]].<ref>[http://pt.chemicalstore.com/Kr%20-%20Krypton.html Properties of Krypton]</ref> Krypton has a [[narcotic]] potency seven times greater than air, so breathing a gas containing 50% krypton and 50% air would cause narcosis similar to breathing air at four times atmospheric pressure. This would be comparable to scuba diving at a depth of {{convert|30|m|ft|abbr=on|sigfig=1}} (see [[nitrogen narcosis]]) and potentially could affect anyone breathing it. Nevertheless, that mixture would contain only 10% oxygen and [[Hypoxia (medical)|hypoxia]] would be a greater concern. |
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==See also== |
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==References== |
==References== |
Revision as of 17:39, 3 January 2013
Krypton | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Pronunciation | /ˈkrɪptɒn/ | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Appearance | colorless gas, exhibiting a whitish glow in an electric field | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Standard atomic weight Ar°(Kr) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Krypton in the periodic table | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Atomic number (Z) | 36 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Group | group 18 (noble gases) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Period | period 4 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Block | p-block | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electron configuration | [Ar] 3d10 4s2 4p6 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 8 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Physical properties | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Phase at STP | gas | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Melting point | 115.78 K (−157.37 °C, −251.27 °F) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Boiling point | 119.93 K (−153.415 °C, −244.147 °F) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density (at STP) | 3.749 g/L | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
when liquid (at b.p.) | 2.413 g/cm3[3] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Triple point | 115.775 K, 73.53 kPa[4][5] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Critical point | 209.48 K, 5.525 MPa[5] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Heat of fusion | 1.64 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Heat of vaporization | 9.08 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Molar heat capacity | 20.95[6] J/(mol·K) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Vapor pressure
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Atomic properties | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Oxidation states | 0, +1, +2 (rarely more than 0; oxide is unknown) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electronegativity | Pauling scale: 3.00 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ionization energies |
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Covalent radius | 116±4 pm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Van der Waals radius | 202 pm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Spectral lines of krypton | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Other properties | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Natural occurrence | primordial | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Crystal structure | face-centered cubic (fcc) (cF4) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Lattice constant | a = 583.57 pm (at triple point: 115.78 K)[7] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Thermal conductivity | 9.43×10−3 W/(m⋅K) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Magnetic ordering | diamagnetic[8] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Molar magnetic susceptibility | −28.8×10−6 cm3/mol (298 K)[9] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Speed of sound | (gas, 20 °C) 221 m·s−1 (liquid) 1120 m/s | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
CAS Number | 7439-90-9 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
History | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Discovery and first isolation | William Ramsay and Morris Travers (1898) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Isotopes of krypton | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Krypton (from [κρυπτός kryptos] Error: {{Lang-xx}}: text has italic markup (help) "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquified air, and is often used with other rare gases in fluorescent lamps. Krypton is inert for most practical purposes.
Krypton, like the other noble gases, can be used in lighting and photography. Krypton light has a large number of spectral lines, and krypton's high light output in plasmas allows it to play an important role in many high-powered gas lasers (krypton ion and excimer lasers), which pick out one of the many spectral lines to amplify. There is also a specific krypton fluoride laser. The high power and relative ease of operation of krypton discharge tubes caused (from 1960 to 1983) the official length of a meter to be defined in terms of the 605 nm (red-orange) spectral line of krypton-86.
History
Krypton was discovered in Britain in 1878 by Sir William Ramsay, a Scottish chemist, and Morris Travers, an English chemist, in residue left from evaporating nearly all components of liquid air. Neon was discovered by a similar procedure by the same workers just a few weeks later.[12] William Ramsay was awarded the 1904 Nobel Prize in Chemistry for discovery of a series of noble gases, including krypton.
In 1970, an international agreement defined the meter in terms of wavelength of light emitted by the krypton-86 isotope (wavelength of 605.78 nanometers). This agreement replaced the longstanding standard meter located in Paris, which was a metal bar made of a platinum-iridium alloy (the bar was originally estimated to be one ten-millionth of a quadrant of the Earth's polar circumference), and was itself replaced by a definition based on the speed of light — a fundamental physical constant. However, in 1927, the International Conference on Weights and Measures had redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths).[13] In October 1983, the same bureau defined the meter as the distance that light travels in a vacuum during 1/299,792,458 s.[14][15][16]
Characteristics
Krypton is characterized as the orginal gangster
Applications
Krypton's multiple emission lines make ionized krypton gas discharges appear whitish, which in turn makes krypton-based bulbs useful in photography as a brilliant white light source. Krypton is thus used in some types of photographic flashes used in high speed photography. Krypton gas is also combined with other gases to make luminous signs that glow with a bright greenish-yellow light.[17]
Krypton mixes with argon as the fill gas of energy saving fluorescent lamps. This reduces their power consumption. Unfortunately this also reduces their light output and raises their cost.[18] Krypton costs about 100 times as much as argon. Krypton (along with xenon) is also used to fill incandescent lamps to reduce filament evaporation and allow higher operating temperatures to be used for the filament.[19] A brighter light results which contains more blue than conventional lamps.
Krypton's white discharge is often used to good effect in colored gas discharge tubes, which are then simply painted or stained in other ways to allow the desired color (for example, "neon" type advertising signs where the letters appear in differing colors are often entirely krypton-based). Krypton is also capable of much higher light power density than neon in the red spectral line region, and for this reason, red lasers for high-power laser light-shows are often krypton lasers with mirrors which select out the red spectral line for laser amplification and emission, rather than the more familiar helium-neon variety, which could never practically achieve the multi-watt red laser light outputs needed for this application.[20]
Krypton has an important role in production and usage of the krypton fluoride laser. The laser has been important in the nuclear fusion energy research community in confinement experiments. The laser has high beam uniformity, short wavelength, and the ability to modify the spot size to track an imploding pellet.[21]
In experimental particle physics, liquid krypton is used to construct quasi-homogeneous electromagnetic calorimeters. A notable example is the calorimeter of the NA48 experiment at CERN containing about 27 tonnes of liquid krypton. This usage is rare, since the cheaper liquid argon is typically used. The advantage of krypton over argon is a small Molière radius of 4.7 cm, which allows for excellent spatial resolution and low degree of overlapping. The other parameters relevant for calorimetry application are: radiation length of X0=4.7 cm, density of 2.4 g/cm3.
The sealed spark gap assemblies contained in ignition exciters used in some older jet engines contain a very small amount of Krypton-85 to obtain consistent ionization levels and uniform operation.
Krypton-83 has application in magnetic resonance imaging (MRI) for imaging airways. In particular, it may be used to distinguish between hydrophobic and hydrophilic surfaces containing an airway.[22]
Although xenon has potential for use in computed tomography (CT) to assess regional ventilation, its anesthetic properties limit its fraction in the breathing gas to 35%. The use of a breathing mixture containing 30% xenon and 30% krypton is comparable in effectiveness for CT to a 40% xenon fraction, while avoiding the unwanted effects of a high fraction xenon gas.[23]
Precautions
Krypton is considered to be a non-toxic asphyxiant.[24] Krypton has a narcotic potency seven times greater than air, so breathing a gas containing 50% krypton and 50% air would cause narcosis similar to breathing air at four times atmospheric pressure. This would be comparable to scuba diving at a depth of 30 m (100 ft) (see nitrogen narcosis) and potentially could affect anyone breathing it. Nevertheless, that mixture would contain only 10% oxygen and hypoxia would be a greater concern.
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References
- ^ "Standard Atomic Weights: Krypton". CIAAW. 2001.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
- ^ Krypton. encyclopedia.airliquide.com
- ^ "Section 4, Properties of the Elements and Inorganic Compounds; Melting, boiling, triple, and critical temperatures of the elements". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. 2005.
- ^ a b Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.121. ISBN 1-4398-5511-0.
- ^ Shuen-Chen Hwang, Robert D. Lein, Daniel A. Morgan (2005). "Noble Gases". Kirk Othmer Encyclopedia of Chemical Technology. Wiley. pp. 343–383. doi:10.1002/0471238961.0701190508230114.a01.
- ^ Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
- ^ Magnetic susceptibility of the elements and inorganic compounds, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
- ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ Patrignani, C.; et al. (Particle Data Group) (2016). "Review of Particle Physics". Chinese Physics C. 40 (10): 100001. Bibcode:2016ChPhC..40j0001P. doi:10.1088/1674-1137/40/10/100001. See p. 768
- ^ William Ramsay, Morris W. Travers (1898). "On a New Constituent of Atmospheric Air". Proceedings of the Royal Society of London. 63 (1): 405–408. doi:10.1098/rspl.1898.0051.
- ^ Burdun, G. D. (1958). "On the new determination of the meter" (pdf). Measurement Techniques. 1 (3): 259–264. doi:10.1007/BF00974680.
- ^ Shri Krishna Kimothi (2002). The uncertainty of measurements: physical and chemical metrology: impact and analysis. American Society for Qualit. p. 122. ISBN 0-87389-535-5.
- ^ Gibbs, Philip (1997). "How is the speed of light measured?". Department of Mathematics, University of California. Retrieved 2007-03-19.
- ^ Unit of length (meter), NIST
- ^ "Mercury in Lighting" (PDF). Cape Cod Cooperative Extension. Archived from the original (PDF) on September 29, 2007. Retrieved 2007-03-20.
- ^ "Energy-saving" lamps
- ^ Properties, Applications and Uses of the "Rare Gases" Neon, Krypton and Xenon
- ^ "Laser Devices, Laser Shows and Effect" (PDF). Retrieved 2007-04-05.
- ^ Sethian, J. "Krypton Fluoride Laser Development for Inertial Fusion Energy" (PDF). Plasma Physics Division, Naval Research Laboratory. pp. 1–8. Retrieved 2007-03-20.
{{cite web}}
: Unknown parameter|coauthors=
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suggested) (help) - ^ Pavlovskaya, GE; Cleveland, ZI; Stupic, KF; Basaraba, RJ; Meersmann, T (2005). "Hyperpolarized krypton-83 as a contrast agent for magnetic resonance imaging". Proceedings of the National Academy of Sciences U.S.A. 102 (51): 18275–9. Bibcode:2005PNAS..10218275P. doi:10.1073/pnas.0509419102. PMC 1317982. PMID 16344474.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Chon, D; Beck, KC; Simon, BA; Shikata, H; Saba, OI; Hoffman, EA (2007). "Effect of low-xenon and krypton supplementation on signal/noise of regional CT-based ventilation measurements". Journal of Applied Physiology. 102 (4): 1535–44. doi:10.1152/japplphysiol.01235.2005. PMID 17122371.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Properties of Krypton
Further reading
- William P. Kirk "Krypton 85: a Review of the Literature and an Analysis of Radiation Hazards", Environmental Protection Agency, Office of Research and Monitoring, Washington (1972)
External links
- Krypton Fluoride Lasers, Plasma Physics Division Naval Research Laboratory