Nitrogen in liquid air

The various components of liquid air can be separated by boiling because each component has a different boiling point. For example, the nitrogen in liquid air boils away before the oxygen. This is called fractional distillation, and it is the basic method of separating the components of crude oil. 

The most familiar mixture of chemically free elements is air, which is about four-fifths nitrogen and one-fifth oxygen, with a measurable trace of inert gases. We ve already seen how these elements can be separated by distilling liquid air because each has a different boiling point. The nitrogen in liquid air will always boil off first. 

Liquid nitrogen (b.p. -209 "C) also is used, but liquid air should not be used. The nitrogen in liquid air boils away first, leaving the oxygen behind. If any organic vapors get into this liquid oxygen, an explosion can result. 

The production of oxygen which accompanies the hydrogen is a surplus product since oxygen is readily separated from nitrogen in liquid air or by the use of molecular sieves or membranes. Hence, by using a carbon anode, the following reactions would occur ... 

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See also in sourсe #XX -- [ ]

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