Condensation polymersAQA A-Level Chemistry: Subtopic test

1. 1
   A textile company makes nylon-6,6 fibre by reacting hexanedioic acid, HOOC(CH₂)₄COOH, with 1,6-diaminohexane, H₂N(CH₂)₆NH₂.

   (a)

   Which linkage joins the monomer units in nylon-6,6?

   [1 mark]

   • AEster
   • BEther
   • CAmide
   • DAmine

   (b)

   Which small molecule is eliminated each time a link forms between the monomers?

   [1 mark]

   • AWater
   • BHydrogen chloride
   • CAmmonia
   • DCarbon dioxide

   (c)

   Explain why the formation of nylon-6,6 is classed as condensation polymerisation.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Kevlar is used in body armour and protective helmets. It is made from benzene-1,4-dicarboxylic acid and benzene-1,4-diamine, and its repeating unit is –NH–C₆H₄–NH–CO–C₆H₄–CO–.

   (a)

   How many N–H bonds are present in one repeating unit of Kevlar as written above?

   [1 mark]

   • A1
   • B2
   • C3
   • D4

   (b)

   Which statement describes the strongest intermolecular forces between Kevlar chains?

   [1 mark]

   • ALondon forces only, because the chains contain benzene rings
   • BIonic bonds between oppositely charged chains
   • CCovalent bonds between neighbouring chains
   • DHydrogen bonds between the N–H of one chain and the C=O of a neighbouring chain

   (c)

   Explain why Kevlar chains are held together very strongly.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Terylene is a polyester used in clothing fibres and, as poly(ethylene terephthalate), in drinks bottles. It is made from benzene-1,4-dicarboxylic acid, HOOC–C₆H₄–COOH, and ethane-1,2-diol, HOCH₂CH₂OH.

   (a)

   Name the linkage in Terylene and explain why each monomer must have two functional groups.

   [3 marks]

   (b)

   A section of a different polyester is shown: –O–CH₂CH₂CH₂–O–CO–CH₂CH₂–CO–O–CH₂CH₂CH₂–O–CO–CH₂CH₂–CO–. Deduce the structures of the two monomers, write the repeating unit and state the number of water molecules eliminated when one repeating unit forms.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials company produces polyamide fibres for ropes and polyester fibres for sailcloth. Its chemists are studying how the structure of each polymer affects the forces between the chains. The company also makes a polyamide from the single monomer 6-aminohexanoic acid, H₂N(CH₂)₅COOH.

   (a)

   Explain the nature of the intermolecular forces between the chains in nylon-6,6 and in Terylene, and explain why hydrogen bonding is possible between nylon-6,6 chains but not between Terylene chains.

   [6 marks]

   (b)

   Explain how 6-aminohexanoic acid forms a polyamide, give the repeating unit, and calculate the relative formula mass of a chain containing 500 repeating units (ignore end groups). Use Ar: H = 1.0, C = 12.0, N = 14.0, O = 16.0.

   [6 marks]

   Total for question 4: 12 marks

End of questions