Argon Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
GERUCHLOSES FARBLOSES FLüSSIGGAS.
PHYSIKALISCHE GEFAHREN
Das Gas ist schwerer als Luft. Es kann sich in tiefer gelegenen Bereichen sammeln und den Luftsauerstoff verdr?ngen.
ARBEITSPLATZGRENZWERTE
TLV: Erstickungsgefahr durch Sauerstoffverdr?ngung.; (ACGIH 2005).
MAK nicht festgelegt (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den K?rper durch Inhalation.
INHALATIONSGEFAHREN
Beim Entweichen aus dem Beh?lter kann das Gas die Luft verdr?ngen. Erstickungsgefahr in geschlossenen R?umen.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Erstickungsgefahr. Die Flüssigkeit kann Erfrierungen hervorrufen.
LECKAGE
Belüftung. Wasserstrahl NIEMALS auf die Flüssigkeit richten. Pers?nliche Schutzausrüstung: Umgebungsluftunabh?ngiges Atemschutzger?t.
S-S?tze Betriebsanweisung:
S38:Bei unzureichender Belüftung Atemschutzger?t anlegen.
Beschreibung
Argon belongs to the family of inert, rare gases
of the atmosphere. It is plentiful compared to
the other rare atmospheric gases; I million ft3
(28 300 m3) of dry air contains 9340 ft3 (264
m3
) of argon. Argon is colorless, odorless,
tasteless, and nontoxic. It is extremely inert and
forms no known chemical compounds. It is
slightly soluble in water.
Chemische Eigenschaften
With the symbol A, argon is a nonflammable
gas; one of the elements in the inert gas category. It is colorless.
Physikalische Eigenschaften
Argon is a colorless, odorless, tasteless, chemically inert noble gas that makes up about0.93% of the Earth’s atmosphere. It is the third most abundant gas in the atmosphere, meaningit is more common than carbon dioxide, helium, methane, and hydrogen.
Its melting point is –189.35°C, its boiling point is –185.85°C, and its density is0.0017837g/cm
3.
Isotopes
There are a total of 24 isotopes of argon, three of which are stable. They areAr-36, which constitutes just 0.3365% of the natural amount of argon; Ar-38, which contributesjust 0.0632% to the amount of argon on Earth; and Ar-40, which, by far, constitutesthe most argon on Earth, 99.6003% of its natural abundance.
Origin of Name
The name “argon” is derived from the Greek word argos, meaning
“inactive.”
Occurrence
Argon is the 56th most abundant element on Earth. It is the most abundant of all the noblegases found in the atmosphere. In fact, the only source of argon is the atmosphere, where it isfound at just under 1% of air by volume.
There are several methods of producing argon. The most common is by fractional distillationof liquid air. Argon is collected as a by-product of this large-scale commercial process.During fractional distillation, argon boils off at its own unique temperature. It is then collectedand purified by passing it through charcoal to filter out helium and other gases, producingsignificant amounts of argon.
Charakteristisch
Although argon is considered chemically inert, at low temperatures it is possible to combineargon with other atoms to form very fragile compounds, which exist only at those verylow temperatures. For instance, it can combine with fluorine and hydrogen to form argonfluorohydride (HArF). It is only slightly soluble in water.
Verwenden
Gas as shield in gas metal-arc welding, in metal processing; carrier in gas-liquid and gas-solid chromatography; gas filler for incandescent light bulbs. Gas in fluorescent tubes analogous to neon lights, but produces a blue-purplish light; in rectifier tubes; in thermometers above mercury; in lasers; wherever an inert atmosphere is desired and the much cheaper nitrogen cannot be used; in ionization chambers and particle counters; in mixtures with He and Ne in Geiger counters; in argon-oxygen-decarburizing process for stainless steel; in manufacture of semiconducting devices; in gas mixtures as the working fluid in plasma arc devices. Liquid as cryogen to produce low temperetures. The isotope 40Ar is always found in minerals contg potassium, since it is a product of 40K decay; measuring the amount of 40Ar and 40K can be used for determining the geologic age of minerals and meteors.
Definition
An inert colorless odorless
monatomic element of the rare-gas
group. It forms 0.93% by volume of air.
Argon is used to provide an inert atmosphere
in electric and fluorescent lights, in
welding, and in extracting titanium and silicon.
The element forms no known compounds.
Symbol: Ar; m.p. –189.37°C; b.p.
–185.86°C; d. 1.784 kg m
-3 (0°C); p.n. 18;
r.a.m. 39.95.
Allgemeine Beschreibung
A colorless odorless noncombustible gas. Heavier than air and can asphyxiate by displacement of air. Exposure of the container to prolonged heat or fire can cause Argon to rupture violently and rocket . If liquefied, contact of the very cold liquid with water may cause violent boiling. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Contacts with water in a closed container may cause dangerous pressure to build.
Reaktivit?t anzeigen
These substances undergo no chemical reactions under any known circumstances. They are nonflammable, noncombustible and nontoxic. They can asphyxiate.
Hazard
Argon is nontoxic, but as an asphyxiant gas, it can smother by replacing oxygen in thelungs.
Health Hazard
Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground.
Brandgefahr
Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket.
Materials Uses
Gaseous argon is noncorrosive and inert, and
consequently may be contained in systems constructed
of any common metals and designed to
safely withstand the pressures involved. At the
temperature of liquid argon, ordinary carbon
steels and most alloy steels lose their ductility and
are considered unsafe for liquid argon service.
Satisfactory materials for use with liquid argon
include austenitic stainless steel (for example,
types 304 and 316), copper, Monel, brass, aluminum,
and other nickel-chromium alloys.
Sicherheitsprofil
A simple asphyxlant
gas. As an inert gas, it has no specific
inherent dangerous properties. Gases of this
type have no specific toxicity effect, but they
act by excluding O2 from the lungs. The
effect of simple asphyxiant gases is proportional to the extent to whch they
dirmnish the amount (partial pressure) of O2
in the air that is breathed. The oxygen may
be diminished to 75% of its normal
percentage in air before appreciable
symptoms develop, and t h s in turn requires
the presence of a simple asphyxiant in a
concentration of 33% in the mixture of air
and gas. When the simple asphyxiant
reaches a concentration of 50%, marked
symptoms can be produced. A
concentration of 75% is fatal in a matter of
minutes. The first symptoms produced by
simple asphyxiant gases such as argon are
rapid respirations and air hunger. Mental
alertness is diminished and muscular
coordination is impaired. Later, judgment
becomes faulty and all sensations are
depressed. Emotional instability often
results and fatigue occurs rapidly. As the
asphyxia progresses, there may be nausea
and vomiting, prostration, and loss of
consciousness, and finally, convulsions, deep
coma, and death.
m?gliche Exposition
Argon is used in metal fabrication
and steel making; as an inert gas shield in arc welding; as
an inert atmosphere in electric lamps; as a blanketing
agent in metals refining (especially titanium and
zirconium).
Lager
Gaseous argon is commonly stored in high pressure
cylinders, tubes, or tube trailers. Liquid
argon is commonly stored at the consumer site
in cryogenic liquid containers and specially
designed vacuum-insulated cryogenic storage
tanks.
All of the precautions necessary for the handling
of any nonflammable gas or cryogenic
liquid must be taken.
Liquid and gaseous systems should be designed
and installed only under the direction of
personnel thoroughly familiar with liquid and
gaseous argon equipment and in compliance
with state, provincial, and local requirements.
Versand/Shipping
UN1006 Argon, compressed, Hazard Class: 2.2;
Labels: 2.2-Nonflammable compressed gas. Cylinders must
be transported in a secure upright position, in a wellventilated
truck. Protect cylinder and labels from physical
damage. The owner of the compressed gas cylinder is the
only entity allowed by federal law (49CFR) to transport
and refill them. It is a violation of transportation regulations
to refill compressed gas cylinders without the express
written permission of the owner.
l?uterung methode
Argon is rendered oxygen-free by passage over reduced copper at 450o, or by bubbling through alkaline pyrogallol and H2SO4, then dried with CaSO4, Mg(ClO4)2, or Linde 5A molecular sieves. Other purification steps include passage through Ascarite (CARE: asbestos impregnated with sodium hydroxide), through finely divided uranium at about 800o and through a -78o cold trap. Alternatively the gas is passed over CuO pellets at 300o to remove hydrogen and hydrocarbons, over Ca chips at 600o to remove oxygen and, finally, over titanium chips at 700o to remove nitrogen. It has also been purified by freeze-pump-thaw cycles and by passage over sputtered sodium [Arnold & Smith J Chem Soc, Faraday Trans 2 77 861 1981]. Arsenic acid (arsenic pentoxide hydrate, arsenic V oxide hydrate, orthoarsenic acid) [12044-50-7] M 229.8 + xH2O, pK 1 2.26, pK 2 6.76, pK 3 11.29 (H3AsO4). The acid crystallises from concentrated solutions of boiling conc HNO3 as rhombic crystals. Dry it in a vacuum to give the hemihydrate (hygroscopic). Heating above 300o yields As2O5. [Thaler Z Anorg Allgem Chem 246 19 1941, Schenk in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 601 1963.]
Waste disposal
Vent to atmosphere. Return
refillable compressed gas cylinders to supplier.
Argon Upstream-Materialien And Downstream Produkte
Upstream-Materialien
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