A laboratory is choosing a pure substance for a reusable temperature indicator. The substance must be solid at 10 ∘C10\,^\circ\mathrm{C}10∘C and remain liquid throughout the temperature range from 75 ∘C75\,^\circ\mathrm{C}75∘C to 100 ∘C100\,^\circ\mathrm{C}100∘C.
| Substance | Melting point (∘C^\circ\mathrm{C}∘C) | Boiling point (∘C^\circ\mathrm{C}∘C) |
|---|---|---|
| A | -18 | 54 |
| B | 32 | 118 |
| C | 86 | 170 |
| D | 18 | 68 |
Which substance should be used for the temperature indicator?
Explain your answer using the data in the table.
The temperature indicator containing the correct substance is heated from 10 ∘C10\,^\circ\mathrm{C}10∘C to 90 ∘C90\,^\circ\mathrm{C}90∘C and then cooled back to 10 ∘C10\,^\circ\mathrm{C}10∘C.
Describe how the arrangement and movement of its particles change during heating.
Explain why the substance can be reused after cooling.
Each substance is heated until it boils.
Describe what happens to its particles during boiling.
Compare the strengths of attraction between the particles in the four substances. Write the substances in order from weakest attractions to strongest attractions and explain your order using the data.
93 exam-style questions on OCR GCSE Chemistry 1.1 The particle model, covering 1.1.1 The particle model and changes of state and 1.1.2 Limitations of the particle model. Each one has a worked solution and a mark scheme showing where the marks go.