IUPAC Name: Argon
Molecular Formula: Ar
Molecular Weight: 39.95
Canonical SMILES: [Ar]
InChI: InChI=1S/Ar
EINECS: 231-147-0
Classification Code: Simple asphyxiant
Product Categories: Industrial / Fine Chemicals; refrigerants; Inorganics; Chemical Synthesis; Compressed and Liquefied Gases; Synthetic Reagents 
Melting point:  -189.2  °C(lit.)
Boiling point:  -185.7  °C(lit.)
Density:  1.784(0 °C)
Vapor density:  1.38 (21 °C, vs air)
Enthalpy of Vaporization: 9.74 kJ/mol 
Vapour Pressure of  Argon (CAS NO.7440-37-1): 343000 mmHg at 25 °C

 Argon was suspected to be present in air by Henry Cavendish in 1785 but was not isolated until 1894 by Lord Rayleigh and Sir William Ramsay in Scotland in an experiment in which they removed all of the oxygen, carbon dioxide, water and nitrogen from a sample of clean air. They had determined that nitrogen produced from chemical compounds was one-half percent lighter than nitrogen from the atmosphere. The difference seemed insignificant, 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. Argon was also encountered in 1882 through independent research of H. F. Newall and W.N. Hartley. Each observed new lines in the color spectrum of air but were unable to identify the element responsible for the lines. Argon became the first member of the noble gases to be discovered. The symbol for argon is now Ar, but up until 1957 it was A.

 Argon (CAS NO.7440-37-1) is usually in the form of gas used as shield in gas metal-arc welding, in metal processing.

Reported in EPA TSCA Inventory.

A simple asphyxiant 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 which they diminish 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 this 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.
Safety Statements:  38 
S38:In case of insufficient ventilation, wear suitable respiratory equipment.
RIDADR:  UN 1006 2.2
F:  4.5-31
HazardClass:  2.2
RTECS:  CF2300000

DOT Classification:  2.2; Label: Nonflammable Gas

  Argon (CAS NO.7440-37-1), its Synonyms are Argon-40 ; Argon, compressed ; Argon, compressed [UN1006] [Nonflammable gas] ; Argon, refrigerated liquid (cryogenic liquid) ; Argon, refrigerated liquid (cryogenic liquid) [UN1951] [Nonflammable gas] . It is colorless odorless noncombustible gas.