7440-37-1 Usage
Description
Argon is a colorless, odorless, tasteless, and chemically inert noble gas that makes up about 0.93% of the Earth’s atmosphere. It is the third most abundant gas in the atmosphere, meaning it is more common than carbon dioxide, helium, methane, and hydrogen. Argon is a nonmetallic element with the symbol Ar and an atomic number of 18. It has a melting point of -189.35°C, a boiling point of -185.85°C, and a density of 0.0017837g/cm3. Argon is slightly soluble in water and forms no known chemical compounds. It is the most abundant of all the noble gases found in the atmosphere and is the 56th most abundant element on Earth.
Uses
Used in Electric and Fluorescent Lights:
Argon is used as an inert gas to fill electric and fluorescent lights, providing a protective atmosphere and preventing corrosion of the filaments.
Used in Welding and Cutting:
Argon is used as a nonoxidizing gas shield for arc welding and cutting, protecting the metal from oxidation and contamination.
Used in Metal Processing:
Argon is used as a blanket in the production of titanium, zirconium, and other reactive metals, and to flush molten metals to eliminate porosity in castings.
Used in Semiconductor Manufacturing:
Argon is used to provide an inert atmosphere in which to grow semiconductor crystals, essential for the production of electronic devices.
Used in Gas-Liquid and Gas-Solid Chromatography:
Argon is used as a carrier gas in gas-liquid and gas-solid chromatography, a technique used to separate and analyze compounds.
Used in Geiger Counters and Ionization Chambers:
Argon is used in mixtures with helium and neon in Geiger counters and as a component in ionization chambers and particle counters.
Used in Plasma Arc Devices:
Argon is used in gas mixtures as the working fluid in plasma arc devices, which are used for cutting, welding, and surface treatment.
Used in Medical Applications:
Argon is used in the argon-oxygen-decarburizing process for stainless steel, which is essential in the medical industry for manufacturing various medical devices and instruments.
Used in Scientific Research:
Argon is used in high-energy physics research, where a tank of liquid argon can form a calorimeter to detect certain subatomic particles.
Used as a Cryogen:
Liquid argon is used as a cryogen to produce low temperatures, which are essential in various scientific and industrial applications.
Used in Double-pane Windows:
Argon is used to fill the space between the panes of higher-quality double-pane windows, reducing heat transfer by gaseous conduction by about 30% compared to air filling.
Used in Gas-Filled Thyratrons and Electron Tubes:
Argon is used in gas-filled thyratrons and electron tubes of various kinds, providing an inert atmosphere for their operation.
Used in Laboratory and Shipping Applications:
Argon atmospheres are used in dry boxes during the manipulation of very reactive chemicals in the laboratory and in sealed-package shipments of such materials.
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.”
Characteristics
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.
History
The presence of Argon in air was suspected by Cavendish in 1785, discovered
by Lord Rayleigh and Sir William Ramsay in 1894.
The gas is prepared by fractionation of liquid air, the atmosphere
containing 0.94% argon. The atmosphere of Mars contains
1.6% of 40Ar and 5 p.p.m. of 36Ar. Argon is two and one
half times as soluble in water as nitrogen, having about the
same solubility as oxygen. It is recognized by the characteristic
lines in the red end of the spectrum. It is used in electric light
bulbs and in fluorescent tubes at a pressure of about 400 Pa,
and in filling photo tubes, glow tubes, etc. Argon is also used
as an inert gas shield for arc welding and cutting, as a blanket
for the production of titanium and other reactive elements,
and as a protective atmosphere for growing silicon and germanium
crystals. Argon is colorless and odorless, both as a
gas and liquid. It is available in high-purity form. Commercial
argon is available at a cost of about 3￠ per cubic foot. Argon
is considered to be a very inert gas and is not known to form
true chemical compounds, as do krypton, xenon, and radon.
However, it does form a hydrate having a dissociation pressure
of 105 atm at 0°C. Ion molecules such as (ArKr)+, (ArXe)+,
(NeAr)+ have been observed spectroscopically. Argon also
forms a clathrate with β-hydroquinone. This clathrate is stable
and can be stored for a considerable time, but a true chemical
bond does not exist. Van der Waals’ forces act to hold the argon.
In August 2000, researchers at the University of Helsinki,
Finland reported they made a new argon compound HArF
4-4 The Elements
by shining UV light on frozen argon that contained a small
amount of HF. Naturally occurring argon is a mixture of three
isotopes. Seventeen other radioactive isotopes are now known
to exist. Commercial argon is priced at about $70/300 cu. ft.
or 8.5 cu. meters.
Hazard
Argon is nontoxic, but as an asphyxiant gas, it can smother by replacing oxygen in thelungs.
Safety Profile
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.
Potential Exposure
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).
Physiological effects
Argon is nontoxic and largely inert. It can act as
a simple asphyxiant by diluting the concentration
of oxygen in air below levels necessary to
support life. Inhalation of it in excessive concentrations
can result in dizziness, nausea,
vomiting, loss of consciousness, and death.
Death may result from errors in judgment, confusion,
or loss of consciousness, which prevents
self-rescue. At low-oxygen concentrations, unconsciousness
and death may occur in seconds
without warning.
Gaseous argon must be handled with all the
precautions necessary for safety as with any
nonflammable, nontoxic compressed gas. All
precautions necessary for the safe handling of
any gas liquefied at very low temperatures must
be observed with liquid argon. Extensive tissue
damage or burns can result from exposure to
liquid argon or cold argon vapors.
storage
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.
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.
Purification Methods
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.
Check Digit Verification of cas no
The CAS Registry Mumber 7440-37-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,4 and 0 respectively; the second part has 2 digits, 3 and 7 respectively.
Calculate Digit Verification of CAS Registry Number 7440-37:
(6*7)+(5*4)+(4*4)+(3*0)+(2*3)+(1*7)=91
91 % 10 = 1
So 7440-37-1 is a valid CAS Registry Number.
InChI:InChI=1/Ar
