A food packaging company is researching the use of condensation polymers to create biodegradable films. The monomers used each contain two functional groups. Explain how the structure of the monomers and the conditions of condensation polymerisation result in the formation of a long-chain polymer, and state what type of small molecule is lost during this process.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Condensation polymerisation is used in the production of a range of materials, including biodegradable packaging. Unlike addition polymerisation, condensation polymerisation involves monomers that each possess two functional groups, and small molecules are released as the polymer chain grows.
Model answer (5 marks)
Each monomer contains two reactive functional groups, so it can react at both ends. During condensation polymerisation the functional groups of two monomers react, forming a covalent bond and releasing a small molecule. Repeating this step joins many monomers, giving a long‑chain polymer. The small molecule lost each time is water.
Examiner tips
- Use the word "condensation" to show you know the process; mention the two functional groups and the release of a small molecule; state the small molecule is water; keep answer concise to fit 5 marks.
Common mistakes
- Failing to mention that each monomer has two functional groups; confusing condensation with addition polymerisation; not naming water as the eliminated molecule.
Mark scheme (5 marks)
- Each monomer has two functional groups
- The two functional groups allow each monomer to bond to two other monomers / bond at both ends
- Many monomers join together / repeat units form a long chain polymer
- A small molecule is lost / eliminated each time two monomers join
- The small molecule lost is water
Key terms in this question
condensation polymerisation · monomers · functional groups · polymer · small molecule
Related
- All OCR A-Level Chemistry A (H432) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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