Describe how the structure of poly(chloroethene), also known as PVC, relates to its use as an electrical insulator.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Poly(chloroethene), or PVC, is an addition polymer made from chloroethene monomers. It is widely used as an insulating coating on electrical wires.
Model answer (4 marks)
PVC is made from many chloroethene monomers joined together by addition polymerisation, forming long chain molecules
The long polymer chains are covalently bonded throughout, with no ions or free electrons present
Because there are no free electrons (or ions), PVC does not conduct electricity
This makes PVC a suitable electrical insulator, preventing current from passing to the outside of the wire and reducing the risk of electric shock
The long polymer chains are covalently bonded throughout, with no ions or free electrons present
Because there are no free electrons (or ions), PVC does not conduct electricity
This makes PVC a suitable electrical insulator, preventing current from passing to the outside of the wire and reducing the risk of electric shock
Examiner tips
- Use the term "addition polymerisation" to show understanding of the synthesis
- Mention the absence of free electrons/ions to justify non‑conductivity
- Explain how this property protects against electric shock
Common mistakes
- Confusing PVC with a salt or ionic compound, implying it has ions
- Failing to mention the covalent nature of the polymer chains
- Over‑generalising and saying all plastics are insulators without justification
Mark scheme (4 marks)
- PVC is made from many chloroethene monomers joined together by addition polymerisation, forming long chain molecules
- The long polymer chains are covalently bonded throughout, with no ions or free electrons present
- Because there are no free electrons (or ions), PVC does not conduct electricity
- This makes PVC a suitable electrical insulator, preventing current from passing to the outside of the wire and reducing the risk of electric shock
Key terms in this question
Related
- All Edexcel GCSE Chemistry (1CH0) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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