Drinks bottles are made from the polyester PET. PET is made by reacting ethanediol with benzene-1,4-dicarboxylic acid.
HO−CH2CH2−OH(Mr=62)HOOC−C6H4−COOH(Mr=166)\mathrm{HO-CH_{2}CH_{2}-OH} (M_{r} = 62) \qquad \mathrm{HOOC-C_{6}H_{4}-COOH} (M_{r} = 166)HO−CH2CH2−OH(Mr=62)HOOC−C6H4−COOH(Mr=166)
The repeat unit of PET contains one unit from each monomer. Two water molecules are formed for every repeat unit in the chain.
Explain why this polymerisation is described as condensation polymerisation.
Calculate the MrM_{r}Mr of the repeat unit of PET.
A factory makes 1.92 kg of PET. Calculate the mass of water formed. Relative formula mass: H2O=18\mathrm{H_{2}O} = 18H2O=18
Calculate the atom economy for making PET in this reaction. Give your answer to three significant figures.
The atom economy for making poly(ethene) from ethene is 100%. Explain why.
Describe the structure of the ester link formed between the two monomers.
37 exam-style questions on Edexcel GCSE Chemistry 10.3 Polymers, covering 10.3.1 Addition polymerisation of alkenes, 10.3.2 Uses and properties of polymers, 10.3.3 Condensation polymers and polyesters, 10.3.4 Problems with polymers and recycling, and 10.3.5 Natural polymers: DNA, starch and proteins. Each one has a worked solution and a mark scheme showing where the marks go.