Cracking

Cracking of hydrocarbons

Breaking apart long hydrocarbons into shorter more useful hydrocarbons

Catalytic cracking

Vaporise hydrocarbon and pass gas over a hot powered aluminium oxide catalyst

Steam cracking

Vaporise hydrocarbon, mix with steam, heat to a very high temperature

Reactant in cracking

Long alkane molecules

Products of cracking

Shorter chain alkanes and alkenes

Test for alkenes

Turn bromine water orange to colourless

Long alkanes are not useful

As they are not very flammable

Shorter chain alkanes are more useful

As they are more flammable

Uses of alkenes

Making polymers and making other chemicals

Reactivity of alkenes

More reactive than alkanes

Ethene

C2H4

propene

C3H6

Butene

C4H8