Amides, polyamides and addition polymersEdexcel International A Level Chemistry: Subtopic test

1. 1
   A technician makes ethanamide, CH₃CONH₂, in a fume cupboard by reacting an acyl chloride with a nitrogen-containing compound.

   (a)

   Which pair of reagents is used to make ethanamide?

   [1 mark]

   • AEthanoic acid and aqueous sodium hydroxide
   • BEthanoyl chloride and concentrated aqueous ammonia
   • CEthanol and ammonia
   • DEthylamine and chloromethane

   (b)

   The technician now reacts ethanoyl chloride with methylamine, CH₃NH₂. Which compound is formed?

   [1 mark]

   • AEthanamide
   • BMethyl ethanoate
   • CN-ethylmethanamide
   • DN-methylethanamide

   (c)

   Write an equation for the reaction of ethanoyl chloride with ammonia, and explain why two moles of ammonia are needed for each mole of ethanoyl chloride.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Nylon-6,6 is made by condensation polymerisation. In a demonstration, a solution of hexanedioyl dichloride, ClOC(CH₂)₄COCl, in an organic solvent is carefully covered with an aqueous solution of hexane-1,6-diamine, H₂N(CH₂)₆NH₂. A film of nylon forms where the two liquids meet and is pulled out as a continuous rope.

   (a)

   Which is the repeat unit of nylon-6,6?

   [1 mark]

   • A–NH(CH₂)₆NHCO(CH₂)₄CO–
   • B–NH(CH₂)₆NHCO(CH₂)₆CO–
   • C–NH(CH₂)₆OCO(CH₂)₄CO–
   • D–NH(CH₂)₅NHCO(CH₂)₄CO–

   (b)

   Which small molecule is eliminated each time a link is formed in this demonstration?

   [1 mark]

   • AH₂O
   • BNH₃
   • CHCl
   • DCl₂

   (c)

   Explain why nylon-6,6 fibres have a high tensile strength.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A chemical company makes two water-soluble addition polymers: poly(ethenol), used for dissolvable laundry bags and for the film around liquid detergent capsules (liquitabs), and poly(propenamide), made from propenamide, CH₂=CHCONH₂. Ethenol, CH₂=CHOH, is unstable, so poly(ethenol) is not made directly from it.

   (a)

   Give the repeat unit of poly(ethenol) and explain, in terms of intermolecular forces, why it dissolves in water.

   [3 marks]

   (b)

   Poly(propenamide) is made from propenamide, CH₂=CHCONH₂. Give its repeat unit, explain why this is addition polymerisation, and explain why poly(propenamide) is not classed as a polyamide although it contains amide groups.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A chemist plans to make a polyamide from butane-1,4-diamine, H₂N(CH₂)₄NH₂, and decanedioyl dichloride, ClOC(CH₂)₈COCl, and wants to compare the properties of the product with those of poly(ethene).

   (a)

   Describe how the polymer is formed from these two monomers. Include the type of polymerisation, the link formed, the small molecule lost, the repeat unit and why long chains form.

   [6 marks]

   (b)

   Explain why this polyamide is expected to have a higher melting temperature and greater tensile strength than poly(ethene) of similar chain length.

   [6 marks]

   Total for question 4: 12 marks

End of questions