C1.5- Products from Oil

Heavier fractions are not very useful (they do not burn easily - can not be used as fuels) so we use a indistrial process called cracking to break apart the long chain alkanes, to produce short chain ones, which can be used as fuels.

Cracking;

• Heavy crude oil fraction is vaporised (extremely high temperatures)
• It is then EITHER passed over a hot catalyst, or mixed with steam.
• Cracking produces a short chain alkane and a alkene.

long chain alkane ---> short chain alkane + alkene

Alkenes;

• Unsaturated hydrocarbons
• have one double carbon bond
• CnH2n
• bromine test- POSITIVE
• orange colour ---> colourless

• Crude oil can also be used to make chemicals
• Important use = making plastics
• Plastics are made of polymers

Polymers = a large molecule made from repeating units of monomers

Monomers = small reactive molecules that react together in repeating sequences to                        form polymers

Uses;

• Poly(ethene) = plastic bags, drink bottles, cling film (easy to shape, strong)
• Poly(propene) = carpet, milk trays, rope (strong, tough)

Polymerisation (creating polymers)

New polymers are being developed for specific purposes;

• ie; response to light (light sensitive plasters)
• ie; response to temperature (shape memory stitches)

New Uses;

• PET is a polymer used to make drinks bottles
• It is now also used to make clothes

Hydrogels;

• Polymer chains with a few cross linking units (between chains)
• This creates a matrix which traps water
• These are used in medicine, eg; for wound dresses
• This is because they provide moist and sterile conditions