Crude Oil

Fossil Fuel – organic matter (once living) e.g. coal (dead plant matter), oil (dead sea creature remains).

Crude oil – made of hydrocarbons. It is the result of heat and pressure on plant and (sea) animal remains over millions of years in the absence of air. This oil (and gas) rises up through permeable rocks and becomes trapped under impermeable rocks, so they have to be extracted by drilling. The oil is called crude oil because it is unrefined which makes it of little use as it is hard to transport.

Fractional Distillation – process used to separate a mixture of liquids that have different boiling points. When the mixture is heated, liquids with low boiling points evaporate and turn to vapour and can then be separated as liquids. Those with high boiling points remain liquids.

Cracking – allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are vaporised and passed over a hot catalyst. This breaks chemical bonds in the molecules, and forms smaller hydrocarbon molecules. Cracking is an example of a decomposition reaction. e.g.