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Crude oil and alkanes

In this chapter you will learn:

  1. What is Crude oil?

  2. What are Alkanes?

  3. Alkane Homologous Series

What is Crude oil?

  • Crude oil is a complex mixture of hydrocarbons. Hydrocarbons are molecules made up of hydrogen and carbon atoms.

  • Crude oil is a limited resource. It is extracted from the earth's surface.

  • Crude oil is a fossile fule. Fossil fuels take many millions years to form. When it is extracted and consumed, there is no way to replace it. The crude oil that has been extracted over the past century was formed millions of years ago.

  • Crude oil is a vital resource. It is an important source of fuels such as petrol, diesel, kerosene, and liquefied petroleum gases.

  • Crude oil is separated by fractional distillation. Petrol is one of the fractions produced from crude oil.

  • Crude oil is an important source of feedstock for making chemicals. The substances in crude oil have different boiling points.

  • Ethene is produced from crude oil. It is used to make polymer.

  • Poly(chloroethene) is a polymer produced from crude oil.


  • Most of the hydrocarbons in crude oil are alkanes.

  • The first four members of the alkanes are methane, ethane, propane and butane.

Alkane Homologous Series

  • The alkanes form a homologous series. Like all series, which have:

  • The same general formula

  • Differ by CH2 in molecular formulae from neighbouring compounds

  • Show a gradual variation in physical properties, such as their boiling and melting points

  • Have similar chemical properties