Why things conduct electricity

2 marks · Normal

Explain why solid sodium chloride does not conduct electricity, but molten sodium chloride does.

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Also accept: Solid sodium chloride does not conduct because the ions are held in a fixed lattice and cannot move.; Molten sodium chloride conducts because the ions are free to move and carry charge.

Common mistakes: Saying electrons move in sodium chloride; Mixing up solid and molten states

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Marking points

M1 · 1 mark · States or explains that in solid sodium chloride (ionic solid), ions are not free to move / fixed in lattice, so cannot conduct electricity.

M2 · 1 mark · Explains that in molten sodium chloride, ions are free to move and can carry charge, so it conducts electricity.

Worked solution

Solid sodium chloride does not conduct electricity because its ions are held in a fixed lattice and cannot move.

Molten sodium chloride conducts electricity because the ionic lattice is broken and ions are free to move, allowing them to carry charge.