1. Fractional distillation

2. Crude oil
Crude oil is a mixture of liquid hydrocarbons, often found together with natural gas.
The lighter hydrocarbons- methane, ethane, propane a butane occur as gases.
The heavier ones, pentane and upwards are in the form of liquids and gases

3. The process of fractional distillation in a fractionating tower
Crude oil is first heated in a furnace.
a mixture of liquid and vapour passes into a tower that is cooler at the top than the bottom.
The vapours pass up the tower via a series of trays containing bubble caps until they arrive at a tray which is sufficiently cool, then they condense into a liquid.
The mixture of liquids that condense on each tray is piped off.

4. The products of fractional distillation
At the bottom of the fractional distillation column there is bitumen which is used for roads and roofing.
The products of fractional distillation

5. The Products of fractional distillation
Above is fuel oil used in ships, factories and central heating.

6. The products of fractional distillation
Above fuel oil is lubricating oil used for waxes and polishes.

7. The products of fractional distillation
Next is diesel oil which powers trains

8. The products of fractional distillation
Above diesel is kerosene ( paraffin oil) which is used for jet fuels and paraffin for lighting.

9. The products of fractional distillation
Above is petrol gasoline which is used as petrol in vehicles.

10. The products of fractional distillation
Next is naphtha used in chemical industry.

11. The products of fractional distillation
Above naphtha is liquefied petroleum gas

12. As you go further up the distillation column the fractions decrease in density and boiling point as they have fewer carbon chains.

13. Industrial cracking
Longer chain hydrocarbons are not as useful and therefore in lower ecological value Crude oil has more of the larger chain hydrocarbons. Many of the longer lengths are broken into shorter lengths. This is industrial cracking

14. Industrial cracking
To meet the demand for the shorter chain hydrocarbons many of the longer chain fractions are broken into shorter lengths.

15. Results of industrial cracking
Some products from industrial cracking are alkenes which are more reactive than alkanes. these alkenes are used as chemical feedstock and converted into a huge range of other compounds including polymers drugs and paint.

16. Polythene
The most important alkene is ethene which is the starting material for poly(ethene) (polythene) and a wide range of other materials.
Polythene is one of the world most popular plastics. It is an enormously versatile polymer which is suited to a wide range of applications.

17. Polymers High density Low density
The two major types of polythenes are:
LDPE (low density polythenes) which are used in films and packaging.
HDPE (high density polythenes) which are used in bags, sacks and food bags.
Low density
High density