Addition polymersAQA A-Level Chemistry: Subtopic test

1. 1
   Poly(chloroethene), PVC, is made by addition polymerisation of chloroethene, CH₂=CHCl. Rigid PVC is used for window frames and drainpipes, whereas a flexible form is used to insulate electrical cables.

   (a)

   Which is the repeating unit of poly(chloroethene)?

   [1 mark]

   • A(–CH₂–CHCl–)
   • B(–CH₂–CH₂–Cl–)
   • C(–CHCl–CHCl–)
   • D(–CH₂–CCl₂–)

   (b)

   What is added to PVC to make it flexible?

   [1 mark]

   • AA cross-linking agent
   • BAn inhibitor
   • CA plasticiser
   • DA monomer

   (c)

   Write an equation for the formation of poly(chloroethene) from chloroethene, showing the repeating unit.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Poly(propene) is used to make ropes, crates and food containers. A section of its chain has the structure –CH₂–CH(CH₃)–CH₂–CH(CH₃)–CH₂–CH(CH₃)–.

   (a)

   Which is the monomer used to make poly(propene)?

   [1 mark]

   • ACH₃CH₂CH₃
   • BCH₃CH=CH₂
   • CCH₂=CH₂
   • DCH₃CH=CHCH₃

   (b)

   Which statement explains why poly(propene) is chemically unreactive?

   [1 mark]

   • AIt contains C=C bonds that are shielded by methyl groups
   • BIt contains many polar bonds that are protected by the chain
   • CIts chains are held together by hydrogen bonds
   • DIt contains only strong, non-polar C–C and C–H bonds

   (c)

   Name the type of intermolecular force between poly(propene) chains and explain why the polymer is solid at room temperature.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Poly(ethene) is used to make carrier bags and plastic film. It is made from ethene by addition polymerisation, and large quantities are produced each year.

   (a)

   Explain how poly(ethene) is formed from ethene. State the repeating unit of poly(ethene) and give the IUPAC name of the polymer made from but-1-ene, CH₂=CHCH₂CH₃.

   [3 marks]

   (b)

   Explain why poly(ethene) is chemically unreactive compared with ethene, and state one environmental consequence of this.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Addition polymers are made in large quantities by the chemical industry. Their properties depend on the groups attached to the carbon chain and on how the polymer is formulated for its use.

   (a)

   Explain how the properties of poly(chloroethene) can be modified by a plasticiser, and relate the properties of the unmodified and modified polymer to their uses.

   [6 marks]

   (b)

   A sample of poly(propene) has an average relative molecular mass of 126 000. Calculate the average number of repeating units in a chain. Then calculate the mass of propene needed to make 2.52 kg of this polymer if the overall yield is 90%. (Ar: C = 12.0, H = 1.0.)

   [6 marks]

   Total for question 4: 12 marks

End of questions