What would happen with non-electrolytes?
2 marks · EasyThe results of an experiment are shown below:
| Substance | State Tested | Conducts Electricity? |
|---|---|---|
| Magnesium chloride | Solid | No |
| Magnesium chloride | Molten | Yes |
| Ethanol | Liquid | No |
Identify whether each substance is ionic, covalent, or a non-electrolyte. Give a reason for your answer in each case.
Magnesium chloride:
Ethanol:
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(a) Ionic; because magnesium chloride conducts electricity when molten but not as a solid, showing it has movable ions when melted. · must show Identification as ionic, Reason based on conductivity when molten
(b) Non-electrolyte (covalent); because ethanol does not conduct electricity in the liquid state, which means it does not produce ions. · must show Identification as non-electrolyte/covalent, Reason based on lack of conductivity
Common mistakes: Stating 'ionic' for ethanol; Not connecting molten state for ionic nature
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Marking points
M1 (a) · 1 mark · Correctly identifies magnesium chloride as ionic and gives a valid reason based on the conductivity results.
M2 (b) · 1 mark · Correctly identifies ethanol as non-electrolyte (or covalent) and gives a valid reason based on its inability to conduct electricity.
Worked solution
a) Magnesium chloride is ionic because it does not conduct as a solid (ions fixed) but does conduct when molten (ions free to move).
b) Ethanol is a non-electrolyte (covalent) because it does not conduct electricity in the liquid state, so does not produce ions.