Argon

CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name                 

Argon [1]

Synonyms                           

Argon-40, argon atom, Argon, compressed, Argon elemental  etc.[2]

IUPAC name

 argon [2]

CAS No

7440-37-1

REACH registration number

EC No

Molecular formula              

Ar

Substance group/chemical family

noble gases/monoatomic

Appearance

Physical state

Odour

Form

Colour

liquid (cryogenic liquid), gas (liquefied gas)

odourless, tasteless

monoatomic gas

colourless    [2]

USES AND HANDLING ISSUES

Relevant identified uses

Argon 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 rectified 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 temperatures. The isotope As(40) is always found in minerals containing potassium, since it is a product of K(40) decay; measuring the amount of AS(40) and K(40) can be used for determining the geologic age of minerals and meteors. [2]

Other uses include non-reactive blanket in the manufacture of titanium and other reactive elements and as a protective atmosphere for growing silicon and germanium crystals. Argon-39 has been used for a number of applications, primarily ice coring. It has also been used for ground water dating. Argon is also used in technical SCUBA diving to inflate the drysuit, due to its nonreactive, heat isolating effect.
Argon as the gap between the panes of glass provides better insulation because it is a poorer conductor of heat than ordinary air. The most exotic use of argon is in the tyre of luxury cars. [3]
 

Handling considerations

Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. [2]

Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container. [2]

PHYSICO-CHEMICAL PROPERTIES

Molecular weight                                  

 39.9 g/mol [2]

Bulk density/Specific gravity

1.633 g/L [2]

1.78*10^-3 g/cm ³ @ 0 °C [3]

Relative vapour density (air = 1): 1.66 [2]

pH

Particle size

EC

Melting point

-189 °C [3]

Boiling point

-185.9 °C [2]

Flash point

Flammability

Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket. [2]

Vapour density

Vapour pressure

Solubility in water

Solubility of gas in water at 20 °C: 33.6 cm3/kg water [2]

Slightly soluble in water (Solubility in water, ml/100ml at 20 °C: 3.4) [2]

Solubility in organic solvents

Soluble in organic liquids  [2]

Solubility in inorganic solvents

Hydrolysis

Ionicity in water

Surface tension

Dispersion properties

Explosiveness

Not combustible. Heating will cause rise in pressure with risk of bursting. [2]

Other properties

Heat (Entalphy) of vaporisation: Liquid (normal BP): 6469 J/mol; Solid: (triple pt): 7.785 kJ/mol. [2]

Stability and reactivity

Chemical stability

Argon is a noble gas and it does not react with any other element. It does not even react at high temperatures or under any other special conditions. [3]

These substances undergo no chemical reactions under any known circumstances. They are nonflammable, noncombustible and nontoxic. They can asphyxiate. [2]

Reactivity hazards

Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container. [2]

Corrosivity

Polimerization

Incompatibility with various substances

Special remarks on reactivity

No rapid reaction with air. No rapid reaction with water. [2]

The gas is heavier than air and may accumulate in lowered spaces causing a deficiency of oxygen. [2]

Physical, chemical and biological coefficient

Koc

Kow

0.74 http://www.hmdb.ca/metabolites/HMDB0037240 [2]

0.94 http://www.ilo.org/dyn/icsc/showcard.display?p_version=2&p_card_id=0154 [2]

pKa

log Kp

Henry-constant

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

General terrestrial fate

General aquatic fate

General atmospheric fate

General persistence and degradability

Abiotic degradation and metabolites

Biodegradation and metabolites

Bioconcentration

Argon does not have any biological use. Diazotrophs, bacteria that absorb nitrogen and convert it to ammonia, may absorb argon, but they cannot apply it. [3]

Volatilization

Photolysis

Hydrolysis

Soil adsorption and mobility

ENVIRONMENTAL CONCENTRATIONS

Measured data

In earth's atmosphere, Ar-39 is made by cosmic ray activity, primarily with Ar-40. In the subsurface environment, it is also produced through neutron-capture by K-39 or alpha emission by calcium. Argon-37 is produced from the decay of calcium-40, the result of subsurface nuclear explosions. It has a half-life of 35 days. Argon is present in some potassium minerals because of radioactive decay of the isotope potassium-40. [3]
Naturally occurring argon is a mixture of three isotopes: Argon-36, Argon-38, Argon-40. [2]

Stable naturally occurring isotopes (mass numbers): 36 (0.377%); 38 (0.063%); 40 (99.600%). Abundance in igneous rock of the earth's crust: 4X10^-2 ppm by weight. The isotope As(40) is always found in minerals containing potassium, since it is a product of K(40) decay. [2] Seventeen radioactive isotopes are now known to exist. [2]

In the earth's atmosphere, noble gases make up about 1% argon is their major component. Concentration in atmosphere: 93.40 ppm by volume. The atmosphere of Mars contains 1.6% of argon-40 and 5 ppm of argon-36. [2]

Argon concentrations ranged from 13.1 to 17.2 micromoles/L (median 15.5 micromoles/L) in samples of groundwater from Orangeburg County, SC, collected in November 1997(1). Argon was reported at a concentration range of 0.7515 to 1.0923 mg/L in ground water samples taken at Mirror Lake, New Hampshire in 1991 and 1992(2). [2]

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem

Acute toxicity (LC50, EC50)

Aquatic systems

Terrestrial systems

Chronic toxicity (NOEC, LOEC)

Aquatic systems

Terrestrial systems

HUMAN HEALTH EFFECTS and PROTECTION

Routes of human exposures

The substance can be absorbed into the body by inhalation. Eye and dermal contact with liquid [2]

General effects

Dizziness. Lethargy. Headache. Suffocation. Eye and dermal contact with liquid results frostbite[2]

Argon is present in the human body in trace amounts. The element is not a dietary requirement. Argon is physiologically ineffective. Health effects from argon present in drinking water are not expected.
The only health effect that may be of importance is argon accumulation in air that is breathed in, leading to oxygen deprivation and asphyxiation. Depending on exposure time, exposure to argon may lead to nausea and sleepiness, followed by breathlessness, unconsciousness, and possible death by asphyxiation. [4]

Endocrine disruption

Mutagenicity

Carcinogenicity

Reprotoxicity

Teratogenicity

Skin, eye and respiratory irritations

Metabolism:

absorption, distribution & excretion

Exposure limits

 Simple asphyxiant. A simple asphyxiant may not be assigned a TLV because the limiting factor is the available oxygen. The liquid may cause frostbite. [2]

Drinking water MAC

Other information

On loss of containment this substance can cause suffocation by lowering the oxygen content of the air in confined areas. [2]

Animal toxicity data

Acute toxicity (LD50)

Acute Exposure to argon was tested for inducing unconsciousness and euthanasia of Sprague-Dawley rats.

Unconsciousness (mean +/- standard error) occurred 87 +/- 8 seconds after short-term exposure to argon.

For euthanasia, argon at approximately 100% increased mean arterial blood pressure but decreased heart rate, induced unconsciousness with hyperreflexia at 54 +/- 4 seconds, and caused death at 197 +/- 20 seconds. [2]

Chronic toxicity (NOEL, LOEL)

ENVIRONMENTAL STANDARDS AND REGULATIONS

REACH/CLP

There is no harmonised classification and there are no notified hazards by manufacturers, importers or downstream users for this substance. [1]

Reported as not meeting GHS hazard criteria by 4 of 581 companies. [2]

Of the 10 notification(s) provided by 577 of 581 companies with hazard statement code(s):

H280 (65.34%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H281 (37.09%): Contains refrigerated gas; may cause cryogenic burns or injury [Warning Gases under pressure]

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. [2]

EINECS regulation

Substances listed in the EINECS, ELINCS, or NLP inventories. [1]

OSHA regulations etc.

Other regulations

EC Inventory, Pre-Registration process, Other [1]

Listed on EU. Dangerous Goods List (RID, Chap. 3.2, Table A), Directive 2008/68/EC, last amended by Regulation 2019/1243/EU, 25 July 2019 [1]

OTHER INFORMATION, SPECIAL REMARKS

Classification and proposed labelling with regard to toxicological data

There is no harmonised classification and there are no notified hazards by manufacturers, importers or downstream users for this substance. [1]

CREATED, LAST UPDATE

Created

2020.05.28.

Last update

2020.06.05.

REFERENCES

[1] ECHA, Argon, https://echa.europa.eu/hu/substance-information/-/substanceinfo/100.028.315, Accessed: 2020.05.28

[2] PubCHem,  Argon  compound, https://pubchem.ncbi.nlm.nih.gov/compound/Argon,  Accessed: 2020.05.28

[3] Lenntech, Periodic elements, Argon  https://www.lenntech.com/periodic/elements/ar.htm,  Accessed: 2020.06.05

[4] Lenntech, Argon and water  https://www.lenntech.com/periodic/water/argon/argon-and-water.htm,  Accessed: 2020.06.05