An explanation linking the following five points:
- water is covalent / water is a molecule
- water has not enough charged particles / not enough ions / no delocalised electrons, so it cannot conduct electricity / carry a current
- magnesium chloride is an ionic compound / substance / solid / lattice
- ions in solid magnesium chloride are fixed in position / do not move
- ions in aqueous magnesium chloride solution are free to move
Marking guidance:
- Do not award the aqueous-conduction mark if the answer mentions electrons moving or delocalised electrons.
- Lose 1 mark if there is any mention of intermolecular forces in magnesium chloride.