Fractional Distillation

This lesson covers:

  1. What 'crude oil' is
  2. How crude oil is formed
  3. How to separate crude oil into its separate components, using fractional distillation

reaction / hydrocarbons / mixture


Crude oil is a of many different compounds. Most of the compounds are .

mixture
hydrocarbons

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Illustration of crude oil barrels

Is crude oil is a finite or renewable resource?

Finite

Renewable

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How crude oil was made:


dinosaurs / plankton / pressure / buried / thousands / millions


  1. Crude oil is formed from the remains of dead plants and animals, particularly .
  2. These organic remains were covered by mud and sand, and in the earth.
  3. Over of years, these organic remains were compressed under a lot of heat and pressure.
  4. The heat and chemically changed the organic remains into crude oil.
plankton
buried
millions
pressure

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Crude oil is a fossil fuel. What else is an example of a fossil fuel?

(Select all that apply)

Wood

Geothermal energy

Coal

Natural gas

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Diagram showing the process of fractional distillation with a fractionating column, cooler at the top, and hot at the bottom.

How fractional distillation works:


condense / boiling / cool / warm / longer / shorter / gas / liquid / high / low


  1. Crude oil is a mixture of hydrocarbons with different points.
  2. The first step is to heat the crude oil to a very temperature so that all of the compounds are evaporated from liquid to .
  3. The hot gaseous hydrocarbons then rise up the fractionating column (because hot gas rises).
  4. As they rise, they down, because the top of the column is cooler than the bottom. 
  5. The hydrocarbons will when they become cooler than their boiling point, and the liquid hydrocarbons then collect in trays and drain out.
  6. The chain hydrocarbons condense at the bottom of the fractionating column because they have high boiling points.
  7. Meanwhile the chain hydrocarbons condense at the top of the column because they have much lower boiling points. 
boiling
high
gas
cool
condense
longer
shorter

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Diagram of a fractional distillation column showing the separation of hydrocarbons into kerosene, diesel, and heavy fuel oil.

Match the hydrocarbons A to C on the diagram above with the following products:


Petrol:

Liquified Petroleum Gas:

Bitumen:

A
B
C

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Which of the following hydrocarbons are used as a fuel?

(Select all that apply)

Petrol

Bitumen

Diesel

Kerosene

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When separating crude oil we use a fractionating column. 


Is the top of the column hotter or cooler than the bottom?

Hotter

Cooler

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Feedstocks and petrochemicals


A lot of people get these terms confused, but it's important to know what they mean.

A feedstock is a raw material used to provide reactants for an industrial reaction.
A petrochemical is a substance made from crude oil, via chemical reactions.

So basically, the different hydrocarbons in crude oil are all feedstocks, but the useful things we then make from those hydrocarbons (polymers, solvents, lubricants, detergents etc.), are all petrochemicals. 

You should also know that the collection of industries and companies that are involved in making petrochemicals are known as the 'petrochemical industry'.

A __________ is a raw material used to provide reactants for an industrial reaction. 

petrochemical 

hydrocarbon

feedstock

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A __________ is a substance made from crude oil via chemical reactions.

petrochemical 

hydrocarbon

feedstock

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