AQA A-Level Chemistry Paper 3, 2021: Question 34
1 mark · Easy difficulty · Multiple Choice
This question focuses on how different types of polymers respond to hydrolysis with concentrated aqueous sodium hydroxide. Most naturally occurring and condensation polymers (like polyamides, polyesters, and proteins) have bonds that can be broken by hydrolysis. However, addition polymers like poly(alkene), which consist only of carbon-carbon single bonds, are resistant and not hydrolysed under these conditions.
Practise this questionQuestion
Question text
34 Which type of polymer is not hydrolysed by heating with concentrated
aqueous sodium hydroxide?
[1 mark]
A poly(alkene)
B poly(amide)
C poly(ester)
D protein
Mark scheme
Show the mark scheme
34 A 1 poly(alkene)
How to answer it
Multiple Choice Explained: Polymer Hydrolysis
Correct Answer: A – poly(alkene)
Why? Poly(alkene)s such as polyethene are made from strong C–C and C–H bonds. These do not contain any hydrolysable functional groups like esters or amides, so they are not broken down by heating with concentrated aqueous sodium hydroxide.
Why B is incorrect:
poly(amide) chains contain amide linkages (–CO–NH–), which can be hydrolysed by hot aqueous alkali, breaking the polymer into a carboxylate salt and an amine.
Why C is incorrect:
poly(ester) chains contain ester bonds (–COO–), which are readily hydrolysed by sodium hydroxide to produce alcohols and carboxylate salts.
Why D is incorrect:
Proteins are natural polyamides made from amino acids linked by peptide bonds. These peptide links can be hydrolysed by hot alkali, so proteins are broken down under these conditions.
Topics
Organic Chemistry · 3.3.12 Polymers
Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.