Question

Explain why, $\mathrm{NaCl}$ is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.

Answer 1

Sodium chloride ($\mathrm{NaCl}$) is an ionic compound. Ionic compounds are those compounds that are made up of ions, i.e., cation and anion and there are lot of attractive forces existing in between the oppositely charged ions.

In Sodium chloride ($\mathrm{NaCl}$), the cation is the Sodium ion (${\mathrm{Na}}^{+}$) and the anion is the Chloride ion (${\mathrm{Cl}}^{-}$).

In the solid form, the ions of Sodium chloride ($\mathrm{NaCl}$) are set in place and cannot move, due to which the ions cannot freely move. Therefore, Sodium chloride ($\mathrm{NaCl}$) does not conduct electricity in solid form.

But Sodium chloride ($\mathrm{NaCl}$) does conduct electricity in an aqueous solution and molten form because the ions are free to move. Due to these freely moving ions (cations and anions), the electricity can pass through aqueous Sodium chloride ($\mathrm{NaCl}$) solution or molten Sodium chloride ($\mathrm{NaCl}$).