The table shows the melting points and boiling points of three substances.
| Substance | Melting point (°C) | Boiling point (°C) |
|---|---|---|
| silicon tetrachloride, SiCl₄ | −69 | 58 |
| hydrogen sulfide, H₂S | −86 | −60 |
| magnesium oxide, MgO | 2852 | 3600 |
Which substance is a liquid at 0 °C?
Predict the state of each substance at −70 °C.
| Substance | State at −70 °C |
|---|---|
| silicon tetrachloride | ? |
| hydrogen sulfide | ? |
| magnesium oxide | ? |
Complete the table.
A student says:
"Silicon tetrachloride has a low boiling point because the covalent bonds between the silicon and chlorine atoms are weak."
Evaluate the student's statement.
Explain why magnesium oxide has a much higher melting point than silicon tetrachloride.
Hydrogen sulfide and silicon tetrachloride both have simple molecular structures.
Relative atomic masses (Ar): H = 1.0, S = 32.1, Si = 28.1, Cl = 35.5
Suggest why hydrogen sulfide has a lower boiling point than silicon tetrachloride.
Use relative formula masses in your answer.
60 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.