Question

How can we obtain different gases from liquid air?

Answer 1

Fractional distillation:

1. Air is a homogenous mixture of gases. It is composed of various concentrations of gases including nitrogen, oxygen, carbon dioxide, argon, and others.
2. By using the fractional distillation technique, we can separate several gases from liquid air.
3. In this process, a liquid mixture is divided into fractions by using the difference between the boiling points of its constituent parts.
4. The first step before fractional distillation is the liquefaction of air. High pressure is used to compress the air, and after that, the temperature is reduced to cool it and liquid air is produced.
5. After that liquid carbon dioxide flows out as dry ice along with water.
6. Following that, the liquid air is passed through the fractional distillation column. Now the liquid air is allowed to warm.
7. It is colder at the bottom of the fractionating column than at the top. Each gas separates at a different temperature depending on its boiling point.
8. Nitrogen has a boiling point of $-{196}^{°}\mathrm{C}$ while oxygen has a boiling point of $-{183}^{°}\mathrm{C}$-. The nitrogen gas would start to escape and would be collected by the outlet.
9. While the oxygen remains at the bottom and is collected as liquid oxygen.

Therefore, we can separate different gases from the liquid air by the fractional distillation process.