Thanks
to Catherine Mckeague 13/2/00
Oil is the remains of tiny plants and animals that lived millions of
years ago. Oil is made up of many
compounds they are mostly hydrocarbons and are very useful in many markets.
Some
of the compounds from oil are used in the form of fuel for cars, aeroplanes and
ships. It can also be turned into
nylon, polythene and other types of plastic. Another use of the compounds from
oil is they can be used to make washing up liquid, washing powder, paints, drugs
and cosmetics.
Oil is
usually found about 3-4km below ground. It
is trapped in rocks. In Britain the
oil bearing rocks lie beneath the north sea.
To obtain oil a hole is bored in the sea bed using a huge drill.
Then the hole is lined with steel and oil is pumped through it, pipes run
along the sea bed and carry the oil to an oil refinery.
Click
here to see a picture of an oil platform.
To refine
the oil, fractional distillation is carried out.
This is because the compounds found in oil either have short carbon
chains or have long carbon chains and to make the best use of the oil it is
separated into groups of compounds that have a similar chain length.
The
distillation of the oil takes place in a tall tower called a fractionating
tower. There the oil is heated up,
the compounds with short chain lengths have a lower boiling point so they will
boil of first. The will rise to the top of the fractionating tower.
The compounds with longer chain lengths have a much higher boiling point
and are collected at the bottom of the fractionating tower.
The different groups of compounds are called fractions.
Some of the fractions from oil are more useful than others, petrol is in greater demand than diesel ,or lubricating oil, so cracking is used to separate them.
Chemistry Department: Loreto College, Coleraine.