A student is given four substances, P, Q, R and S. Each substance has one of these types of structure: giant ionic, simple molecular, giant covalent or metallic.
The table shows some data about the four substances.
| Substance | Melting point in °C | Boiling point in °C | Conducts when solid? | Conducts when molten? | Solubility in water |
|---|---|---|---|---|---|
| P | 1083 | 2567 | yes | yes | insoluble |
| Q | −95 | 69 | no | no | insoluble |
| R | 1710 | 2230 | no | no | insoluble |
| S | 714 | 1412 | no | yes | soluble |
Determine the physical state of Q at 25 °C. Justify your answer.
Deduce the type of structure of each substance, P, Q, R and S. Give a reason from the data for each deduction.
Explain why S conducts electricity when molten but not when solid.
Another substance, T, has a melting point above 3500 °C and conducts electricity when solid. A student says that T must be a metal. Suggest why the student may be wrong.
Another student says: "S must be ionic because it dissolves in water." Evaluate this statement.
48 exam-style questions on Edexcel GCSE Chemistry 2.5 Types of substance, covering 2.5.1 Classifying substances by structure and bonding, 2.5.2 Properties of ionic and simple molecular substances, 2.5.3 Giant covalent structures: diamond and graphite, 2.5.4 Fullerenes, graphene and simple polymers, 2.5.5 Properties of metals and non-metals, and 2.5.6 Limitations of bonding models and representations. Each one has a worked solution and a mark scheme showing where the marks go.