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Crude Oil Fractions & Their Uses | Organic Chemistry | Chemistry | FuseSchool


In our other videos, we learnt how fractional
distillation is used to separate hydrocarbons into fractions with a similar boiling point. In
this video, you will learn the names of some important fractions and their uses. As you are now aware, large hydrocarbons have
high boiling points and so are removed at the bottom of the fractionating column. Smaller
molecules condense higher up the column. We will now take a look at some of the common
fractions as we move down from the top of the fractionating column. Some of the smallest molecules are between
1 and 4 carbons in length. This fraction has such a low boiling point that it is still as a gas when
it is removed from the very top of the fractionating column. This fraction is known as refinery gas or
bottled gas. Bottled gas because it can be stored in bottles under high pressure. You could well have seen
bottles of propane or butane running barbeques or heaters in your home and these are examples
of the Refinary gas fraction. Petrol is between 5-7 carbons in length. It
is still a fraction of small chain hydrocarbons and therefore these vaporise at a low temperature
and are easily ignited. This makes it useful as a fuel in the internal combustion engine of a car. Naphtha is not such a useful fuel but is a
valuble source of organic molecules which can be cracked to make more fuels or form alkenes. Alkenes
can be turned into polymers and polymers can make plastics which are used in our everyday lives. Kerosene has an important use as a fuel for
jet engines in aircraft and even in some rockets. Kerosine is also called Paraffin in some parts
of the world and is a common fuel burnt in Paraffin or Kerosene lamps used for lighting. Diesel is the next fraction. It is a common
fuel in cars, vans and lorries. It is not as volatile as petrol and instead of spark ignition like petrol,
it ignites under compression. Below Diesel is the residue fractions: fuel oil used as a fuel in power stations
and ships, lubricating oil which sticks to surfaces and reduces friction and protects from rust. And finally
waxes which along with the oils can be used for polishing surfaces. The very bottom fraction is Bitumen. This
is the thick black adhesive used on roads either as the surface finish or combined with stone chippings
to create a solid resistant material. It can also be used to cover roofs due to its waterproofing
properties. All these fractions are separated from the
crude oil mixture. To try explain the importance of crude oil consider this – there is estimated
to be over 1 billion cars in the world of which many will use petroleum as fuel. There are many million
flights per year, each burning Kerosene fuel. Not forgetting the mass of plastic that is made
each day for products and their packaging and even the Bitumen used to surface and resurface roads
around the world. As you can see, crude oil containts many useful products that just need to be
separated from the mixture! Now at the end of this lesson you should have
a better understanding of why crude oil is such a valuable resource and use of each of the main
fractions.

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