Give one reason why molten sodium chloride conducts electricity. Refer to ions in your answer.
How to approach this question
For a substance to conduct electricity, it must contain charged particles that are free to move. In solid sodium chloride, the ions are charged but held in fixed positions. What happens to the ions when the sodium chloride melts?
Full Answer
The ions are free to move.
In solid ionic compounds like sodium chloride, the ions (Na⁺ and Cl⁻) are held in fixed positions within the giant ionic lattice. Although they are charged, they cannot move, so solid sodium chloride does not conduct electricity. When it is melted, the strong electrostatic forces are overcome, and the ions are free to move and carry an electrical current.
Common mistakes
✗ Just saying "it contains ions" - this is also true for the solid.\n✗ Mentioning electrons - conduction in ionic compounds is due to the movement of ions, not electrons.
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