Page 9 - Curriculum Visions Dynamic Book

 Fractional distillation of air. The liquid air
is pumped into a fractionating column and subjected to pressure and temperature changes to separate the component gases that make up air.
Air is cooled
to -190°C and pressurised to generate liquid air.
 Nitrogen has many industrial applications. It creates an inert environment for storing experimental samples during research.
Why nitrogen is liquified under pressure
Chemists make use of the Gas Laws when they are separating out nitrogen from other atmospheric gases. These laws describe how a gas behaves, and are one of the cornerstones of science.
To make nitrogen into a liquid, where the volume occupied by the molecules is much smaller than a gas, the gas volume has to be reduced.
One of the Gas Laws states:
The volume of a gas reduces as the temperature is lowered and/ or if the pressure is increased.
This law means that chemists can work with a combination
of lowering the temperature and raising the pressure to find the most economical way of liquifying the gas.
Nitrogen gas. Nitrogen boils at -196°C. It
is used to make fertilisers and nitric acid.
Some liquid oxygen is used to cool the nitrogen and liquify it. This is possible because the nitrogen is at a higher pressure than the oxygen and so has a higher boiling point.
 Liquid nitrogen boiling vigorously at room temperature
volatile: readily forms a gas.
Argon gas. Argon boils at -186°C and is used as an unreactive filling for some light bulbs.
Liquid oxygen. Oxygen boils at -183°C and is used for breathing apparatus.
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