We all have been fascinated by the sparkling, incandescent and fluorescent lights at the streets, during festivals and at the time of celebrations. The beauty is not only due to the bulbs and tubes that lit it but also in the element that makes it unique and attractive. It is strange that such elements have been very important in our day–to–day lives and influence us indirectly. One such significant element is Argon. The name ‘argon’ itself suggests ‘lazy’ or ‘inactive’. Hence, Argon is a noble gas. In fact, it was the first noble gas to be discovered. Symbolised as ‘A’ or ‘Ar’, it is a chemical element with an atomic number 18. In 1957, the symbol was changed to Ar by IUPAC. Argon is a colourless and odourless gas present in the atmosphere and does not undergo any chemical reactions. Being the third most common gas in the atmosphere, it is approximately 23.8 times abundant as carbon dioxide and is more than 500 times as abundant as neon. It does not make any true chemical compounds, however, it glows violet in a gas discharge tube.
Most of the elements discovered earlier and so far were produced with many agendas and observations on the minds of the chemists and scientists. However, in case of Argon, it was discovered as a result of trying to explain why the density of Nitrogen extracted from the air differed from that obtained by the decomposition of ammonia. Argon became recognised in 1894 when Lord Rayleigh and William Ramsay had first separated it from liquid air. However, prior to its discovery, a critical observation was made by Henry Cavendish in 1785 who noted that about 1% of air would not react even under the most extreme conditions and that 1% was Argon. Ramsay removed all the nitrogen by reacting it with hot magnesium. The residue left behind would not react and further examination led to new groups of red and green lines and hence, it was confirmed that it was a new element.
As discussed earlier, the element is obtained from the air as a by–product of the production of oxygen and nitrogen. Generally, Argon is made or prepared by fractionating liquid air. About 0.94% of the earth’s atmosphere and 1.6% of the Mar’s atmosphere contains Argon.
Some properties of Argon are:
- The freezing point of Argon is -189.20C and boiling point is -185.70C.
- Although exceptionally it forms a hydrate with a dissociation pressure of 105 atm at 00C, it is considered to be a noble or inert gas and does not form true chemical compounds.
- With approximately the same solubility as oxygen, Argon is about two and a half times more soluble in water than nitrogen.
- Its emission includes a characteristic set of red lines.
- The element is colourless and odourless, both in its gas and liquid forms.
Isotopes of Argon include 40Ar, 36Ar and 38Ar. However, out of these, 40Ar is stabilized by the decay of the naturally occurring 40K that has a half–life of about 1.25x109. This happens due to the electron capture or positron emission. These ratios and properties are useful and are used to determine the age of rocks by the method of K-Ar dating.
Some of the common uses of Argon are:
- At a pressure of about 400 Pa, Argon is used in electric light bulbs and in fluorescent tubes.
- It is also used in filling photo tubes, glow tubes and more.
- Used as an inert gas shield for arc welding and cutting, it is widely used as a blanket during the production of titanium and other reactive elements.
- Its acts as a protective atmosphere for growing silicon and germanium crystals.
- It is commonly used for thermal insulation in energy efficient windows.
- It is widely used in technical scuba diving to inflate dry suit as it is inert and has a low thermal conductivity.
Argon is an inert gas and is classified as a simple asphyxiant. Excessive inhalation of Argon may lead to dizziness, nausea, vomiting, loss of consciousness and death. On its loss of containment, Argon evaporates very quickly causing super saturation of the air with serious risk of suffocation when in confined areas. On the other hand, as Argon is naturally occurred in the environment, it does not cause any ecological damage.
