Edexcel iGCSE Chemistry - Topic 4d Alkenes

Alkane

A homologous series of saturated hydrocarbons

Alkene

A homologous series of unsaturated hydrocarbons containing a carbon-carbon double bond

Craking

A reaction where long chains of alkanes are heated up to 600-700C with a catalyst adn broken down into shorter chains of alkanes with an alkene

Addition reaction

The reaction of an alkene with a halogen to produce a halogenoalkane

What is the functional group of alkenes

A carbon-carbon double bond

Why are alkenes described as unsaturated

Because they have double bonds

How many carbons are found in ethene

2

How many carbons are found in propene

3

How many carbons are found in butene

4

How many carbons are found in pentene

5

Why is there no alkene with one carbon

Because you cannot have a carbon double bonded to itself

Why is cracking used?

To turn less valuable, longer chains of alkanes into more valuable shorter chains of alkanes and an alkene

Cracking

A long chain alkane is heated with a catalyst where it will break apart into a shorter chain alkane and an alkene

What are shorter chain alkanes more useful as

Fuels

What can alkenes be used to make

Plastics

What can change with cracking

The products, even if the reactants are the same

Test for alkene

If it can decolourise bromine water, it is an alkene