Addition polymerisation is used to make poly(ethene) from ethene monomers. Describe the process of addition polymerisation and explain why poly(ethene) is considered an environmental concern.

Pearson Edexcel International GCSE Chemistry (4CH1) — 4.8 Synthetic polymers · Describe and Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Addition polymerisation:
1. Many small ethene monomers join to form a long chain polymer.
2. The C=C double bond in each ethene opens/breaks, allowing the monomers to link.

Environmental concern:
Poly(ethene) is not biodegradable – it cannot be broken down by living organisms.
It persists in the environment, accumulates in landfills and can harm wildlife for a long time.

Examiner tips

  • Use the term "addition polymerisation" and mention the opening of the C=C bond. Show the chain‑forming process. State that poly(ethene) is non‑biodegradable and mention persistence and wildlife harm.

Common mistakes

  • Confusing addition with condensation polymerisation. Saying the polymer is biodegradable. Forgetting to mention the double bond opening.

Mark scheme (4 marks)

  1. Many small molecule monomers join/bond together to form a long chain polymer
  2. The double bond in ethene (C=C) opens/breaks to allow monomers to join
  3. Poly(ethene) is not biodegradable / cannot be broken down by living organisms
  4. It persists in the environment / accumulates in landfill / harms wildlife for a long time

Key terms in this question

addition polymerisation · monomer · polymer

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