Poly(propene) and nylon are both polymers but are made by different types of polymerisation. Describe the differences between addition polymerisation and condensation polymerisation.

Edexcel GCSE Chemistry (1CH0) — 10.4 Polymers (Chem only) · Describe · 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. Monomers contain C=C double bonds (unsaturated).
2. Polymerisation proceeds by opening the double bond; only the polymer is formed – no small molecule is released.

Condensation polymerisation:
1. Monomers possess two different functional groups (e.g. –NH₂ and –COOH).
2. During polymerisation a small molecule (water or HCl) is released along with the polymer.

Examiner tips

  • Use the word ‘addition’ and ‘condensation’ to label each part clearly.
  • Mention the key features (unsaturated monomers, no by‑product vs. two functional groups, small‑molecule release).
  • Show the difference in the number of products produced.

Common mistakes

  • Confusing the type of monomer (e.g. saying condensation uses unsaturated monomers).
  • Forgetting to state that condensation releases a small molecule such as water.

Mark scheme (4 marks)

  1. Addition polymerisation involves monomers with a C=C (carbon–carbon double bond) / unsaturated monomers
  2. In addition polymerisation, only one product is formed (the polymer) / no small molecule is released
  3. Condensation polymerisation uses monomers with two different functional groups (e.g. amine and carboxylic acid groups)
  4. In condensation polymerisation, a small molecule (water or hydrogen chloride) is also produced / released

Key terms in this question

addition polymerisation · condensation polymerisation · polymer

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