Poly(propene) is a polymer used to make ropes, food containers and carpets. Propene is an alkene with the molecular formula C₃H₆. Explain how poly(propene) is formed from propene monomers, and describe one difference in properties between poly(propene) and propene that makes poly(propene) more suitable for making ropes.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Poly(propene) is a widely used polymer. It is produced from propene, a monomer obtained from the cracking of crude oil fractions. Poly(propene) is strong, flexible, and does not react easily with chemicals.
Model answer (5 marks)
Poly(propene) is produced by addition polymerisation. The double bond in each propene monomer (C=C) opens and the monomers link together to form a long chain, giving a polymer with a much higher molecular mass. No other product is released.
Because the polymer has a much higher molecular mass and a longer chain, it is stronger and more durable than the small propene molecule, making it suitable for rope manufacture.
Because the polymer has a much higher molecular mass and a longer chain, it is stronger and more durable than the small propene molecule, making it suitable for rope manufacture.
Examiner tips
- Use the term ‘addition polymerisation’ and mention the opening of the C=C bond.
- Show that many monomers join to give a long chain and that no small molecule is released.
- Explain that the higher molecular mass gives greater strength for ropes.
Common mistakes
- Calling the process ‘condensation polymerisation’ instead of ‘addition’. Forgetting to state that no other product is released. Describing the polymer as having a lower boiling point rather than higher.”
Mark scheme (5 marks)
- The process is called addition polymerisation
- The double bond in propene (C=C) breaks / opens
- Many propene monomers join together to form a long chain / polymer
- No other product / no small molecule is released during the reaction
- Poly(propene) has a much higher molecular mass / longer chain than propene, making it stronger / more durable / giving it a higher boiling point so it is a solid at room temperature, suitable for making ropes
Key terms in this question
Related
- All Edexcel A-Level Chemistry (9CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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