Engineers are choosing materials for two parts of a kiln.
| Material | Structure | Thermal data |
|---|---|---|
| P | Long molecules with strong covalent bonds along each chain and weaker intermolecular forces between chains | Begins to soften at 135 ∘C135\,^\circ\mathrm{C}135∘C |
| Q | A rigid, continuous network of atoms joined by covalent bonds | Melting point of 1650 ∘C1650\,^\circ\mathrm{C}1650∘C |
The door seal must remain flexible at 80 ∘C80\,^\circ\mathrm{C}80∘C without softening.
The firing spacer must remain hard at 1000 ∘C1000\,^\circ\mathrm{C}1000∘C.
No other properties need to be considered.
Explain which material should be used for the door seal and which material should be used for the firing spacer. Use the data and ideas about bonding and structure in your answer.
122 exam-style questions on OCR GCSE Chemistry 2.3 Properties of materials, covering 2.3.1 Carbon bonding and the variety of organic compounds, 2.3.2 Diamond, graphite, fullerenes and graphene, 2.3.3 Bond strength, changes of state and predicting states, 2.3.4 Bulk properties and types of bonding, and 2.3.5 Nanoparticles: scale, surface area, uses and risks. Each one has a worked solution and a mark scheme showing where the marks go.