Finite resurce of natural fuels like coal and gas formed by the remains of living orgaisms

Hydrocarbons in different fractions have different boiling points. The forces between the molecules are intermolecular forces and are broken during boiling. The molecules of the liquid separate as molecula of a gas. Large molecules such as those of bitumen and heavy oil have strong forces of attraction. A lot of energy is needed to break the forces between the molecules. These fractions have high boiling points. Smaller molecules such as petrol have weak attractive forces between them and are easily separated. Less energy is needed to break the forces between the molecules. These fractions have low boiling points.

There may be political problems related to the extraction of crude oil. The UK is dependent on politically unstable countries. Oil producing nations can set high prices and cause problems for the future supply of non-oil producing nations.

Oil slicks can damage birds' feathers and cause their deaths. Clean-up operations use detergents that can damage wildlife.

Because th demand for oil and its products is very high, there is conflict between the needs for making petrochemicals and for making fuels. Naptha is in high demand for usse in medicines, plastics and dyes.

Cracking is a process that turns large alkane molecules into smaller alkane and alkene molecules.

For example C8 H18 --> C2 H4 + C6 H14

Energy value

Pollution causd

Toxicity

Availability

Ease of use

Cost

Storage

Incomplete combustion: fuel + oxygen(not plenty) --> carbon/carbon monoxide + water

Complete combustion: fuel + oxygen --> carbon dioxide + water (+energy)

Flavour enhancers

Emulsifiers

Antioxidants

Food colours

Acid + Alcohol --> Ester + water (concentrated sulphuric acid is used as a catalyst)

Easily evaporates

Non-toxic

Insoluble in water

Doesn't irritate the skin

Doesn't react with water