Ethene is produced by cracking long-chain hydrocarbons. Ethene can be used as a monomer to make poly(ethene). Describe the process of addition polymerisation and explain why ethene, rather than ethane, is able to undergo this reaction.

1. Addition polymerisation is a chain reaction in which many small molecules (monomers) join together to form a very large molecule – a polymer.
2. In this process the monomers link together without any small molecules being lost; the only product is the polymer.
3. Ethene has a carbon–carbon double bond, which makes it unsaturated.
4. The double bond opens (breaks) during the reaction, allowing the monomers to link together.
5. Ethane lacks a double bond, so its carbon–hydrogen bonds cannot open and it cannot undergo addition polymerisation.