AQA GCSE Chemistry Chemistry Paper 2 (Foundation), November 2020: Question 6

✅ Correct Answer

Disposal at the end of useful life

💡 Key Knowledge

Every LCA assesses 4 distinct stages:

1. Extracting and processing raw materials
2. Manufacturing and packaging
3. Use and operation during lifetime
4. Disposal at the end of useful life

Whether an item decomposes in landfill (biodegradable) or is reprocessed (recycled) happens entirely at the disposal stage.

❌ Common Errors

Selecting "Manufacturing and packaging" because recycling produces new items. Remember: in an LCA, the fate of the plate itself belongs strictly under disposal.

✅ Correct Answers

• Heating in a furnace
• Shaping wet clay

💡 Key Knowledge

Pottery and brick ceramics are produced using clay:

• Wet clay is easily moulded into shape while soft.
• It is then heated to very high temperatures in a kiln/furnace, which removes water and locks strong bonds into place.

🧠 Exam Technique: Elimination

Cross out options from other topics:

• "Melting sand and boron trioxide" creates borosilicate glass, not clay ceramics.
• "Galvanising with zinc" is used to prevent the rusting of iron/steel.
• "Forming a composite" involves reinforcement embedded in a matrix (e.g. fiberglass).

✅ Correct Answers

The name for very large molecules such as poly(propene) is polymers (or polymer).

The name of the alkene used to produce poly(propene) is propene (also allow monomer).

💡 Key Knowledge

Polymer names follow a simple naming convention:

poly(monomer name)

Therefore, removing the prefix "poly" gives the starting alkene: propene .

❌ Common Errors

Writing "propane" (an alkane) instead of "propene" (an alkene). Addition polymers are formed from unsaturated monomers containing double bonds (alkenes).

✅ Correct Answers

• Cracking
• Fractional distillation

💡 Key Knowledge

To produce alkenes for plastics:

1. Fractional distillation: Separates crude oil into fractions of similar boiling points (alkanes).
2. Cracking: Breaks long-chain alkane molecules down into smaller, more useful molecules (short-chain alkanes + alkenes).

❌ Common Errors

Selecting Fermentation (used to produce ethanol from sugars) or Chromatography (an analytical separation technique, not an industrial synthesis route).

✅ Correct Answer

Covalent

💡 Key Knowledge

Poly(propene) is composed exclusively of non-metal atoms (carbon and hydrogen). Non-metal atoms share pairs of electrons to form covalent bonds.

❌ Common Errors

Confusing intermolecular forces (weak attractions between separate polymer chains) with the chemical bonds holding the atoms inside each chain together (strong covalent bonds).

✅ Correct Answers

06.6: Thermosetting (or thermoset) [1 mark]

06.7: Any one of the following [1 mark]:

• Polymer A has crosslinks (between polymer molecules / chains).
• Polymer B has no crosslinks (between polymer molecules / chains).

💡 Key Knowledge

• Thermosoftening polymers (Polymer B): Tangled chains with only weak intermolecular forces between them. They melt easily when heated ( 50 °C ) and can be reshaped.
• Thermosetting polymers (Polymer A): Chains are joined by strong covalent crosslinks. They do not melt when heated; they char instead.

🧠 Exam Technique: Follow the Prompt

The question explicit states: "You should refer to crosslinks in your answer."

If you only write "Polymer A has stronger intermolecular forces" or "Polymer A has higher melting point", you score 0 marks. You must state which polymer does or does not possess crosslinks.