Addition polymers and polymer disposalEdexcel International A Level Chemistry: Subtopic test

1. 1
   A packaging company makes reusable storage crates from poly(propene). The polymer is produced by heating propene under pressure with a catalyst, and the company recycles off-cuts from the moulding process.

   (a)

   Which statement correctly describes the addition polymerisation of an alkene such as propene?

   [1 mark]

   • ATwo different monomers join, releasing a small molecule such as water each time a bond forms.
   • BSaturated monomer molecules join by breaking their C–C single bonds.
   • CThe monomer molecules react together to form the polymer plus a second product.
   • DUnsaturated monomer molecules join to form a long chain, and the polymer is the only product.

   (b)

   A batch of poly(propene) has an average relative molecular mass of 42 000. (Ar: H = 1.0, C = 12.0.) Approximately how many propene molecules joined to form an average polymer chain?

   [1 mark]

   • A500
   • B1000
   • C1500
   • D2000

   (c)

   Draw the repeat unit of poly(propene) and explain, in terms of the structure of propene, why its formation is an addition polymerisation.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An electrical contractor specifies poly(chloroethene), PVC, as the insulation for cables because it is flexible and does not conduct electricity. PVC is made by addition polymerisation of chloroethene, CH₂=CHCl.

   (a)

   Which compound is the monomer from which poly(chloroethene) is made?

   [1 mark]

   • AChloroethene, CH₂=CHCl
   • BChloroethane, CH₃CH₂Cl
   • C1,2-dichloroethane, ClCH₂CH₂Cl
   • D3-chloropropene, CH₂=CHCH₂Cl

   (b)

   What is the relative molecular mass of the repeat unit of PVC? (Ar: H = 1.0, C = 12.0, Cl = 35.5.)

   [1 mark]

   • A27.0
   • B61.5
   • C62.5
   • D125.0

   (c)

   Explain why bromine water is decolourised by chloroethene but not by PVC.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A non-stick pan manufacturer coats its pans with poly(tetrafluoroethene), PTFE. The repeat unit of PTFE is –CF₂–CF₂–. A chemist at the company is preparing advice on what should happen to the polymer at the end of the product's life.

   (a)

   Deduce the structural formula and name of the monomer used to make PTFE, and write an equation, using n, for its polymerisation.

   [3 marks]

   (b)

   A sample of PTFE has an average relative molecular mass of 2.5 × 10⁵. (Ar: C = 12.0, F = 19.0.) Calculate the average number of monomer molecules in each chain. Then state two reasons why waste PTFE causes disposal problems.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A town council collects mixed plastic waste, including poly(ethene) carrier bags and poly(chloroethene) (PVC) pipe off-cuts. Landfill space is running out. The council is considering incinerating the waste to generate electricity, and is also asking a supermarket chain to replace poly(ethene) carrier bags with bags made from a biodegradable polymer.

   (a)

   Discuss the problems that incinerating this mixed plastic waste would cause, and explain how chemists limit these problems.

   [6 marks]

   (b)

   Evaluate the proposal to replace poly(ethene) carrier bags with bags made from a biodegradable polymer.

   [6 marks]

   Total for question 4: 12 marks

End of questions