Edexcel IGCSE Chemistry 4.49C polyester formulae

Practise polyester-formula questions by drawing repeat units, reversing to monomers and balancing condensation equations.

Exam points

Draw the polyester repeat unit from a diol and dicarboxylic acid, including the ester link.
Work backwards from a polyester repeat unit to the two monomer structural formulae.
Complete polyester equations with one repeat unit and the correct number of H2O molecules.

[Maximum number: 3]

Ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ , can be manufactured from ethene and steam using a phosphoric acid catalyst.

Butanedioic acid and ethanediol react together to form a polyester and water.

Complete the equation.

Show only one repeat unit of the polyester.

Figure for Question 4.49C Polyester formulae question 1 — Edexcel IGCSE Chemistry

- correct ester link
- rest of polymer structure correct with extension bonds
- $\ce{2H2O}$

Marking guidance:
- Use the verified answer images for the polyester repeat unit.
- If brackets and n are present, the equation must be fully balanced with n in front of each reactant and 2nH2O for full marks; otherwise maximum 2 marks.
- If a dimer is drawn with $\ce{OH}$ at one end and $\ce{COOH}$ at the other, a mark can be awarded for $\ce{H2O}$ without the 2 because this equation is then balanced, so the ester-link and water marks can be awarded.

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4.49C Polyester formulae question 1