AQA GCSE Chemistry Chemistry Paper 2 (Higher), 2023: Question 8
12 marks · Standard Demand difficulty · Short Answer
Analyze various aspects of synthetic and naturally occurring polymers, including drawing polymer structures, identifying composites, calculating relative formula mass, and identifying DNA and starch structures.
Practise this questionQuestion
Question text
08 This question is about polymers.
Chloroethene can be used to produce an addition polymer called poly(chloroethene).
The displayed structural formula of chloroethene is
08.1 Draw a circle around the functional group on the displayed structural formula that
allows chloroethene to produce an addition polymer.
[1 mark]
08.2 Complete the equation for the production of poly(chloroethene) from chloroethene.
[3 marks]
08.3 Poly(ethene) can be strengthened with wood particles to make a building material.
The building material consists of a wood particle reinforcement embedded in a
poly(ethene) matrix.
What general name is given to materials like this?
[1 mark]
08.4 The amino acid beta-alanine has the formula
H2NCH2CH2COOH
*25* Beta-alanine polymerises to produce a polypeptide and a small molecule.
Name the small molecule produced when beta-alanine polymerises.
[1 mark]
08.5 An amino acid can be represented as:
The relative formula mass (Mr) of this amino acid is 75
Calculate the relative formula mass of the section of this amino acid molecule
represented by
Relative atomic masses (Ar): H = 1 C = 12 N = 14 O = 16
[2 marks]
Relative formula mass =
Figure 6 represents part of a naturally occurring polymer molecule produced
from glucose.
Figure 6
08.6 Draw a circle around the repeating unit in the polymer in Figure 6.
[1 mark]
08.7 Suggest the identity of this polymer.
[1 mark]
Figure 7 represents the structure of a naturally occurring polymer.
Figure 7
08.8 Give the general name for the four different monomers which make up the structure
shown in Figure 7.
[1 mark]
08.9 Name the shape of the structure shown in Figure 7.
[1 mark]
Mark scheme
Show the mark scheme
Question 8
AO /
Question Answers Extra information Mark
Spec. Ref.
08.1 1 AO1
4.7.3.1
AO /
Spec. Ref.
08.2 C-C bond 1 AO2
4.7.3.1
3x C-H and 1x C-Cl bonds 1
2x single bonds extending 1
through brackets
and
n below halfway
an answer of
scores 3 marks
AO /
Spec. Ref.
08.3 composites 1 AO1
4.10.3.3
AO /
Spec. Ref.
08.4 water allow H2O 1 AO1
4.7.3.3
AO /
Spec. Ref.
08.5 (Mr of NH2 and COOH) = (2 × 1) AO2
+ 14 + 12 + (2 × 16) + 1 =)
4.3.1.2
61 1
4.7.3.3
(Mr of section = 75 – 61) allow correct use of incorrectly 1
= 14 determined Mr of NH2 and
COOH
AO /
Question Answers Mark
Spec. Ref.
08.6 1 AO2
4.7.3.1
4.9.1.3
AO /
Spec. Ref.
08.7 starch allow cellulose 1 AO3
allow glycogen 4.7.3.4
allow polysaccharide
AO /
Spec. Ref.
08.8 nucleotides 1 AO1
4.7.3.4
AO /
Spec. Ref.
08.9 double helix ignore DNA 1 AO1
4.7.3.4
Total Question 8 12
How to answer it
Polymers, Composites, and Naturally Occurring Macromolecules
What this question tests
This question assesses your understanding of addition polymerisation (drawing monomers and polymers), composite materials, condensation polymerisation (amino acids and water loss), simple relative formula mass (Mᵣ) calculations, and naturally occurring polymers (starch, cellulose, and DNA).
Identifying the Functional Group for Addition Polymerisation
Correct Answer
Draw a circle directly around the carbon-to-carbon double bond ( C=C ).
Key Knowledge
- Addition polymers are made from monomers that are unsaturated (contain a double covalent bond).
- The C=C double bond is the functional group that breaks open to allow monomer units to join together.
Exam Technique
Be precise with your pencil! If your circle accidentally includes the Hydrogen or Chlorine atoms, the examiner may not award the mark. Keep the circle tightly focused on the C=C double bond.
Completing the Addition Polymer Equation
Correct Answer
Inside the brackets, draw:
- A single carbon-carbon bond: C-C
- Three C-H bonds and one C-Cl bond (matching the monomer)
- Two single bonds extending horizontally outwards through the brackets
- A subscript n at the bottom right of the bracket
How to Draw It
Imagine the double bond of the monomer "opening up" like arms. The structure inside the brackets should look like this:
-( C(H)(H) - C(Cl)(H) )-n
Common Errors to Avoid
- ❌ Leaving the double bond: Do not draw a double bond C=C inside the polymer brackets. It must be a single bond C-C .
- ❌ Missing the extension bonds: The single bonds on the left and right must go completely through the brackets to show the chain continues.
- ❌ Forgetting 'n': The lowercase n represents a large number of repeating units. Don't leave it out!
Composite Materials
Correct Answer
composites (or composite materials)
Key Knowledge
A composite consists of two materials with different properties:
- The reinforcement (fibres or fragments, here: wood particles).
- The matrix which surrounds and binds the reinforcement together (here: poly(ethene)).
Condensation Polymerisation By-products
Correct Answer
water (accept H₂O )
Key Knowledge
Amino acids have two different functional groups:
- An amine group ( -NH₂ )
- A carboxylic acid group ( -COOH )
When they react to form a polypeptide chain, they undergo condensation polymerisation, releasing a small molecule (water) for every link made.
Calculating Relative Formula Mass (Mᵣ)
Step-by-Step Calculation
- Identify the known end groups: H₂N- and -COOH .
- Calculate the Mᵣ of the end groups:
• H₂N = 14 + (2 × 1) = 16
• COOH = 12 + (2 × 16) + 1 = 45
• Total end groups = 16 + 45 = 61 - Subtract from the total Mᵣ:
• Middle section = Total Mᵣ - End groups Mᵣ
• Middle section = 75 - 61 = 14
Calculation Traps
Watch out for Oxygen! The carboxylic acid group ( -COOH ) contains two oxygen atoms. A common mistake is only adding the mass of one oxygen (16) instead of two (32).
Natural Polymers: Glucose Derivatives
08.6 Correct Answer
Draw a circle around one complete repeating glucose ring unit (including one of the single oxygen atoms linking the rings together).
08.7 Correct Answer
starch (also accept cellulose, glycogen, or polysaccharide)
Key Knowledge
Glucose is a simple sugar (monosaccharide). When plants link glucose molecules together in long chains, they form complex carbohydrates (polysaccharides) like starch (used for energy storage) or cellulose (used for cell walls).
Natural Polymers: DNA
08.8 Correct Answer
nucleotides
08.9 Correct Answer
double helix
Key Knowledge
DNA (deoxyribonucleic acid) is a vital natural polymer that encodes genetic instructions. It consists of two polymer chains made from four different monomers called nucleotides (A, T, C, G), wound around each other in a double helix shape.
Topics
Chemistry · C7: Organic Chemistry · C10: Using Resources · C3: Quantitative Chemistry
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 2 (Higher), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.