1. 1
   A plastics factory produces poly(ethene) bags and containers by polymerising large quantities of ethene gas (C2H4). Quality control chemists study the repeating unit of the polymer formed and compare it with the structure of the original monomer.

   (a)

   A plastics factory produces poly(ethene) bags by polymerising ethene (C2H4) monomers. This process, in which many small alkene monomers join together to form one very large molecule, is called:

   [1 mark]

   • AAddition polymerisation
   • BCondensation polymerisation
   • CFractional distillation
   • DFermentation

   (b)

   The quality control chemists compare the repeating unit of poly(ethene) with the ethene monomer used to make it. Which statement correctly describes this relationship?

   [1 mark]

   • AThe repeating unit has fewer atoms than the monomer, because water is lost during the reaction
   • BThe repeating unit has the same atoms as the monomer, but the C=C double bond becomes a single bond
   • CThe repeating unit contains a C=C double bond, identical to the monomer in every way
   • DThe repeating unit has completely different atoms from the monomer

   (c)

   Draw a description in words of how the poly(ethene) repeating unit forms from two ethene monomers, and explain why poly(ethene) is described as a very large molecule compared with the monomer it is made from.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A textile manufacturer produces polyester fabric for clothing by reacting ethanediol with hexanedioic acid. Each monomer has two functional groups per molecule, and the reaction releases small molecules of water as the long polymer chain forms.

   (a)

   A textile manufacturer produces polyester fabric by reacting ethanediol with hexanedioic acid. Each of these monomers has two functional groups per molecule, and the reaction releases small molecules of water as the polymer forms. This type of polymerisation is called:

   [1 mark]

   • ANeutralisation
   • BAddition polymerisation
   • CCondensation polymerisation
   • DElectrolysis

   (b)

   The manufacturer's chemists note that both ethanediol and hexanedioic acid must have two functional groups per molecule (not just one) for the reaction to form a long polymer chain rather than a small molecule. Why is this the case?

   [1 mark]

   • ATwo functional groups are needed only to increase the melting point of the final product
   • BTwo functional groups allow each monomer to bond only once, forming a very short molecule
   • CTwo functional groups prevent the monomers from reacting with each other at all
   • DTwo functional groups allow each monomer to bond to two neighbouring monomers, one on either side, extending the chain

   (c)

   State the small molecule released during the condensation polymerisation of ethanediol and hexanedioic acid, and explain why this reaction is classified as a condensation reaction rather than an addition reaction.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biologist studying natural materials in living organisms compares synthetic polyester with several important natural polymers: proteins, starch, cellulose and DNA, investigating the types of monomer from which each is built.

   (a)

   Name the type of monomer from which proteins are made, and the type of monomer from which DNA is made, and state the type of polymerisation by which both are formed.

   [3 marks]

   (b)

   The biologist explains that proteins can be made from many different amino acids joined in a specific sequence, while starch and cellulose are both made from many repeating glucose units, yet these natural materials have very different properties and functions. Explain how the same general process (condensation polymerisation) can produce such structurally and functionally different natural polymers.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials engineer is designing packaging and clothing solutions for two different products: one requiring a flexible, lightweight plastic film, and another requiring a strong, durable synthetic fabric, and is deciding between an addition polymer and a condensation polymer for each.

   (a)

   A materials engineer is designing packaging for two different products: one requiring a flexible, lightweight plastic film, and another requiring a strong, durable synthetic fabric. She considers using an addition polymer for the film and a condensation polymer for the fabric. Explain the differences between addition polymerisation and condensation polymerisation, including the types of monomer involved and whether any small molecules are lost, and explain why each process might be chosen for a different product.

   [6 marks]

   (b)

   The engineer's colleague suggests that instead of using purely synthetic polymers, some natural condensation polymers, such as proteins, might also be worth studying for inspiration in designing new strong, flexible materials. Explain how proteins are formed by condensation polymerisation of amino acids, and discuss why studying natural polymers such as proteins might help engineers design new synthetic materials.

   [6 marks]

   Total for question 4: 12 marks

End of questions