how to seperate the oxygen from air mention the procedure
Answers
Fractional distillation of liquid air
You need to be able to explain how nitrogen and oxygen are obtained from the air.
You will recall that about 78% of the air is nitrogen and 21% is oxygen. These two gases can be separated by fractional distillation of liquid air.
Liquefying the air
Air is filtered to remove dust, and then cooled in stages until it reaches –200°C. At this temperature it is a liquid. We say that the air has been liquefied.
Here's what happens as the air liquefies:
water vapour condenses, and is removed using absorbent filters
carbon dioxide freezes at –79ºC, and is removed
oxygen liquefies at –183ºC
nitrogen liquefies at –196ºC
The liquid nitrogen and oxygen are then separated by fractional distillation.
Fractional distillation
Fractional distillation
The liquefied air is passed into the bottom of a fractionating column. Just as in the columns used to separate oil fractions, the column is warmer at the bottom than it is at the top.
The liquid nitrogen boils at the bottom of the column. Gaseous nitrogen rises to the top, where it is piped off and stored. Liquid oxygen collects at the bottom of the column. The boiling point of argon - the noble gas that forms 0.9% of the air - is close to the boiling point of oxygen, so a second fractionating column is often used to separate the argon from the oxygen.
Uses of nitrogen and oxygen
liquid nitrogen is used to freeze food
food is packaged in gaseous nitrogen to increase its shelf life
oil tankers are flushed with gaseous nitrogen to reduce the chance of explosion
oxygen is used in the manufacture of steel and in medicine
your answer,
by the process of fractional distillation....
principle involved is the difference between the boiling point of the two mixtures...