Description
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Argon is a colorless, odorless, noble gas. Argon is a very stable noble gas, is one of the most common noble gases to be found on Earth, and it is nontoxic. Argon has an atomic weight of 39.948, a melting point of - 308.7 °F, and a boiling point of - 302.4 °F. Some common uses of argon include: as a component in fluorescent tubes, photo tubes, glow tubes, and electric light bulbs, to create a protective blanket in the production of reactive elements and for the growth of silicon and germanium crystals.
Isolation
Argon is isolated from the air through cryogenic fractional distillation. This process is not carried out on a small scale in laboratories, but rather through large scale processes for industrial purposes.
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The atmosphere around earth is composed of 0.94% argon. Today, cryogenic fractional distillation isolates elemental argon from the air using extremely high temperatures to liquefy the air, and then extremely low temperatures to separate the argon from the liquefied elements. In this process, krypton, neon, nitrogen, oxygen, and xenon are produced.
Before technology was available to use cryogenic fractional distillation, elemental argon was isolated using a multi step system. The first step used an air separation distillation system and a low pressure column to isolate air with high concentrations of argon. The crude argon was heated and reacted with nitrogen and oxygen to form argon in water. The water was removed from the argon through condensation and absorption processes. The gas that remained was cooled to low temperatures in order to remove the small amounts of remaining nitrogen and hydrogen from the argon gas mixture. The end result was pure argon.