Question

Why do ionic compounds conduct electricity in a molten state?

Answer 1

Hint: The conduction of electricity requires the presence of free electrons to move freely. Think of what could possibly restrict this in a solid compound.

Step-by-Step Solution:
Substances can conduct electricity if there is a way for charge to flow through that substance. For a substance to conduct electricity, it needs to contain some sort of charge carrier - this could be an electron or an ion - that is free to move within the substance.
Let us now analyse the properties of ionic compounds in both of these states: solid and molten.
In molten state or dissolved state ionic compounds conduct electricity because they contain charged particles called cations and anions. These ions are free to move to conduct electricity. There are plenty of free ions in the molten state or dissolved state which are able to conduct electric current.
In solid state the movement of ions is restricted because the ions are held together in fixed positions by strong electrostatic force and cannot move freely.
Thus, ionic compounds conduct electricity in molten state or solution as in molten state, the electrostatic forces of attraction between the oppositely charged ions are overcome due to the heat but in solid state they do not conduct electricity.

Note: Remember that while the molten state and dissolved state of ionic compounds conduct electricity similarly well, this does not make them the same. Since, in the molten state the electrostatic forces of attraction are overcome by heat whereas in dissolved state, these forces are very weak as a result of the medium they are operating in.