A sealed temperature sensor contains a layer of insulating material between an electrical conductor and its metal casing. The insulating material remains contained if it melts.
The sensor operates at 900 ∘C900\,^{\circ}\mathrm{C}900∘C. The insulating material must prevent an electrical current from passing between the conductor and the casing during operation and after cooling.
Two ionic compounds are considered for the insulating material.
| Material | Ionic compound | State at 900 ∘C900\,^{\circ}\mathrm{C}900∘C | State at 25 ∘C25\,^{\circ}\mathrm{C}25∘C |
|---|---|---|---|
| P | sodium chloride | molten | solid |
| Q | magnesium oxide | solid | solid |
Explain which material should be used in the sensor.
In your answer, predict whether each material would conduct electricity at 900 ∘C900\,^{\circ}\mathrm{C}900∘C and at 25 ∘C25\,^{\circ}\mathrm{C}25∘C, and explain each prediction.
119 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.