Condensation polymersEdexcel A-Level Chemistry: Subtopic test

1. 1
   Poly(ethylene terephthalate), PET, is used to make drinks bottles. It is made from benzene-1,4-dicarboxylic acid, HOOC–C₆H₄–COOH, and ethane-1,2-diol, HOCH₂CH₂OH.

   (a)

   Which linkage joins the monomer units in PET?

   [1 mark]

   • AAmide, –CONH–
   • BEther, –O–
   • CA carbon–carbon single bond formed when C=C opens
   • DEster, –COO–

   (b)

   Ten molecules of the acid and ten molecules of the diol join to form one single chain. How many molecules of water are eliminated?

   [1 mark]

   • A9
   • B10
   • C19
   • D20

   (c)

   Explain why the formation of PET is called condensation polymerisation, and why each monomer must have two functional groups.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Nylon-6,6 is a polymer used in ropes and fabrics. It is made from hexanedioic acid, HOOC(CH₂)₄COOH, and 1,6-diaminohexane, H₂N(CH₂)₆NH₂.

   (a)

   How many carbon atoms are in one repeat unit of nylon-6,6?

   [1 mark]

   • A12
   • B6
   • C10
   • D14

   (b)

   Which statement about the formation of nylon-6,6 is correct?

   [1 mark]

   • AThe C=C bond in each monomer opens
   • BA molecule of water is eliminated each time an amide link forms
   • CA molecule of hydrogen chloride is eliminated each time a link forms
   • DOnly one type of monomer is needed

   (c)

   Write the structural formula of the repeat unit of nylon-6,6.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Two biodegradable plastics are each made from a single monomer. Poly(lactic acid), PLA, is made from 2-hydroxypropanoic acid, CH₃CH(OH)COOH. A polyamide is made from 6-aminohexanoic acid, H₂N(CH₂)₅COOH.

   (a)

   Explain how PLA forms from a single monomer, and write the structural formula of its repeat unit.

   [3 marks]

   (b)

   A chain of the polyamide made from 6-aminohexanoic acid has a relative formula mass of 11 300. Deduce the repeat unit and the type of link, and calculate the number of repeat units. Assume the end groups can be ignored.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A polymer research group studies condensation polymers. Known examples are PET (used for bottles) and nylon-6,6 (used for fibres). The group has also made a new polyester Z, whose repeat unit is –OCH₂CH₂CH₂O–CO(CH₂)₄CO–.

   (a)

   Explain how PET and nylon-6,6 are each formed, and how their formation differs from the addition polymerisation of ethene.

   [6 marks]

   (b)

   Deduce the monomers that form polyester Z, and calculate the number of repeat units in a chain of Z with a relative formula mass of 37 200 (ignore end groups). Explain your working.

   [6 marks]

   Total for question 4: 12 marks

End of questions