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Alkanes, alkenes and plasticsAlkenes

Alkanes are useful as fuels and alkenes are used to make chemicals such as plastic, which is a polymer. Polymers are long chain molecules that occur naturally in living things and can also be made by chemical processes in industry.

Part of Chemistry (Single Science)Crude oil, fuels and organic chemistry

Alkenes

Alkenes are a of that contain a carbon-carbon double bond. The number of hydrogen in an alkene is double the number of carbon atoms, so they have the general formula:

CnH2n

For example, the molecular formula of ethene is C2H4, while for propene it is C3H6.

Here are the names and structures of four alkenes:

Table containing the molecular formula and structural formula of ethene, propene, but-1-ene and but-2-ene.

Butene has two straight-chained isomers, as the double bond can be placed in two different places or locations:

  • but-1-ene (double bond with the first carbon)
  • but-2-ene (double bond with the second carbon)

Alkenes are unsaturated, meaning they contain a . This bond is why the alkenes are more reactive than the .