Question

Why is an ionic solid non-conductive, but conductive in aqueous solution?

Answer 1

Because the ions that constitute ionic compounds are not free to move in the solid state...........

Explanation:

The generic ionic solid is `MX`, and consists of equal number of `M^+` and `X^-` ions that are held together in a non-molecular, electrostatically bound lattice. The ions are not free to move in the solid state, and thus cannot carry a charge.

In certain circumstances, with certain solvents, for instance water, the ionic solid can dissolve to produce `M^(+)(aq)` and `X^(-)(aq)` ions that are free to move in solution. We write `M^(+)(aq)` to represent the aquated ion, i.e. `[M(OH_2)_6]^+` or something similar. And in solution these ions can carry a charge in that the ions are mobile.

Water is an excellent solvent for solvating ions. However, it does not solvate all ions, and it is not the only solvent available.