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.