Why things conduct electricity
2 marks · NormalExplain why solid sodium chloride does not conduct electricity, but sodium chloride solution does.
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Also accept: In solid sodium chloride, ions are held in place and cannot move, so it does not conduct. In solution, the ions are free to move, allowing electricity to be conducted.
Common mistakes: Saying electrons carry charge in ionic compounds; Not mentioning the movement or freedom of ions
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Marking points
M1 · 1 mark · States that ions are not free to move in solid sodium chloride / ions are fixed in the lattice.
M2 · 1 mark · States that ions are free to move in solution, so the solution conducts electricity.
Worked solution
In solid sodium chloride, the ions are held tightly in a lattice and cannot move, so they cannot carry charge.
In sodium chloride solution, the ions are free to move and can carry charge through the liquid.