Question

A solid sample of a compound a liquid sample of the same compound are each tested for elecrical conductivity.Which test conclusion indicates that the compound is ionic?

Answer 1

• An ionic compound will not conduct electricity as a solid.
• It will conduct electricity when melted.
• Some ionic compounds are soluble. Their solutions in water also conduct electricity.

Explanation

A substance should contain charged particles that are free to move around in order to conduct electricity.

Ionic compounds contain an ocean of ions. They carry either positive or negative charges. Attractions between them hold them in a rigid lattice under the solid state. Those ions are unable to move. The ionic compound can't conduct electricity.

Melting the ionic compound will break the lattice. Those ions are now free to move to conduct electricity. Dissolving the compound in water will also free the ions. As a result, those solutions will also conduct electricity.

Conductivity under different states distinguishes between ionic compounds, molecular compounds, and metals.

• Ionic compounds conduct electricity when melted but not as a solid.
• Molecular compounds have no charged particles. They do not conduct electricity even when melted.
• Valence electrons in metals are free to move both when the metal is a solid and when it is melted. Metals conduct electricity under both solid and liquid states.