Nitrogen makes up approximately 78% of the air around us. In this lesson we will learn
about nitrogen, its properties and its real-life applications. Nitrogen is a
colourless, odourless gas at standard ambient temperature and pressure.
Nitrogen is extracted from air using liquefaction and fractional distillation.
These processes are explained in another lesson. Atmospheric nitrogen is naturally
fixed or reacted to form a compound, into soils by lightning or certain types of
bacteria. Nitrogen is an essential element in the structure of proteins and
DNA but plants cannot obtain it from the air as the nitrogen nitrogen triple bond
is very strong, so it has to be fixed into soils. This is the part of a much
larger and important nitrogen cycle as explained in another lesson. We will
first discuss the uses of nitrogen as a gas. Nitrogen gas is used in the Haber
Process for the industrial manufacture of ammonia. Ammonia is an important
starting material in the production of nitric acid, fertilisers,
pharmaceutical products and explosives. For certain chemical and industrial
processes an unreactive atmosphere may be required. This means that the
reaction conditions must be made to be oxygen free. This is because unwanted
oxidation reactions may occur or oxygen may bind to certain substrates
and prevent a reaction from happening. These reactions are conducted under a
nitrogen or argon atmosphere. Nitrogen is cheaper than argon and more readily
available and would therefore be the choice atmosphere for industrial
chemists in such scenarios.
The next time you purchase a bag of chips or crisps notice how the bag is
rather puffy. The gas inside the bag is actually nitrogen. As much oxygen is
possible is removed so to prevent bacteria from growing thereby increasing its
shelf life. In fact nitrogen is very important in the packaging of many food
products, from fruits and vegetables to processed foods such as your bag of
chips or crisps. Without it spoilage will occur much quicker, leading to
increased waste production. A method to separate compounds on their volatility
is called gas chromatography. This is done by flushing an inert or
unreactive gas through a provided sample injected in a gas chromatograph. This gas
can be helium or nitrogen. Nitrogen is the gas of choice for this technique
because the supply of helium on earth is dangerously low and as a consequence its
market value has significantly increased. Liquid nitrogen also has many real-life
applications. Nitrogen boils at minus 1 96 degrees Celsius, so you can imagine
how absolutely cold nitrogen is. Now you may wonder, what is the use of something that
is so cold. Some industrial reactions are highly exothermic and liquid
nitrogen is used cool down such reactions. Liquid nitrogen is also used
to preserve many biological specimens such as blood and tissue samples.
Therefore it plays an important role in scientific research. It is also used in
the medical field to remove warts and others skin abnormalities. The wart is
frozen by applying liquid nitrogen and it is then safely removed. This is called
cryotherapy, where cryo is used to describe very low temperature conditions.
Research studies conducted at very low temperatures
is called cryogenics.