What does crude oil consist of? What does fractional distillation do to crude oil?

1 Answer
Jan 31, 2016

Answer:

Crude oil is raw material extracted from the ground, which consists of many different hydrocarbons. Fractional distillation is the process of separating these different hydrocarbons.

Explanation:

Crude Oil:

  • Crude oil is a mixture of hydrocarbons that exists as a liquid in natural underground reservoirs and remains a liquid when brought to the surface.

  • You will often hear oil referred to as petroleum. However, petroleum is a collective term that includes crude oil, condensate and gas.

  • The various forms of crude oil are extracted from the earth using a drilling process, and then further refined into fuels such as petrol, kerosene, diesel and many heavy waxes.

  • Petroleum plants can use the process known as cracking to reduce the size of very large hydrocarbon molecules in to more applicable molecules for every day life.

Fractional Distillation:

  • As the different components in crude oil have different boiling points, the substances in crude oil can be separated using fractional distillation.
  • The crude oil is evaporated and its vapours allowed to condense at different temperatures in the fractionating column. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms.
  • Hydrocarbon molecules with a higher molecular weight have stronger dispersion forces which subsequently increases their boiling point. For example fuel oil.

  • Hydrocarbon molecules with a lower molecular weight have weaker dispersion forces which subsequently decreases their boiling point. For example refinery gases.

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/rocks/fuelsrev3.shtml