Cracking and Alkenes

the shorter hydrocarbon chains that are separated from fractional distillation and useful because they are flammable and good fuels however the longer ones aren’t as useful because they are thick viscous liquids. so we can break them down into shorter ones by cracking. they also are necessary to increase supple of fuels that are in high demand

breaking down long chain hydrocarbons into shorter ones by heating them. its a thermal decomposition reaction

catalytic cracking and steam cracking

• heat up long chain hydrocarbons and vapourise them (turn into gas) • gas comes into contact with hot powdered aluminium oxide (catalyst) which splits them apart into 2 smaller hydrocarbons

• heat up long chain hydrocarbons and vapourise them (turn into gas) • mix gas with steam and heat to a very high temperature causing the long hydrocarbons to split apart into shorter ones

the long chain alkane splits into a short chain alkane and a alkene the number of carbons on each side will stay the same however the alkene has a double bond

instead of waste products they can be used to produce polymers and other materials

another homologous series of hydrocarbons with a carbon to carbon double bond

CnH2n

saturated: only single bonds (alkanes) unsaturated: double bonds (alkenes)

if you add alkenes to a solution of bromine water it will turn it from orange to colourless, it will decolourise it