A sample contains two substances, A and B. The table shows their structures, melting points and boiling points.
| Substance | Structure | Melting point (°C) | Boiling point (°C) |
|---|---|---|---|
| A | simple molecular | 48 | 186 |
| B | ionic lattice | 734 | 1380 |
The sample is heated to 210 °C. Any gas formed leaves the heated chamber and passes into a collector kept at 100 °C. Substances that are not gases remain in the heated chamber.
Explain how this process separates substance A from substance B. Include the final state of substance A and the direction of energy transfer when it changes state in the collector.
The heated chamber also has an outlet through which liquids can be removed. A technician proposes raising the temperature of the chamber to 800 °C and using this outlet to collect substance B.
Evaluate this proposal. Include the energy needed for the change of state of substance B.
The collected material can be used in another process only if every molecule in it is substance A.
Before the mixture is heated, a small amount of a simple molecular substance C is accidentally added. The table shows data for substance C.
| Melting point (°C) | Boiling point (°C) |
|---|---|
| 62 | 205 |
Explain whether the material collected at 100 °C is suitable for the other process.
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.