NaCl does not conduct electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state. Explain.

The electrical conductivity of a substance is closely related to the movement of charged particles, specifically ions, within the material. In the case of NaCl (sodium chloride), its conductivity behavior in different states can be explained by the arrangement and mobility of ions.

Solid State:
In the solid state, NaCl exists as a crystalline lattice structure. The ions (Na⁺ and Cl⁻) are held in fixed positions within the lattice by strong electrostatic forces. Since the ions cannot move freely, NaCl in its solid state does not conduct electricity. The absence of free, mobile charge carriers (ions or electrons) prevents the flow of an electric current.

Aqueous Solution:
When NaCl is dissolved in water (forming an aqueous solution), the crystal lattice breaks down, and the Na⁺ and Cl⁻ ions become surrounded by water molecules. The water molecules separate the ions and reduce the electrostatic forces holding them in fixed positions. As a result, the ions gain mobility, and Na⁺ and Cl⁻ ions can move freely in the solution. This movement of charged particles allows for the conduction of electricity through the solution.

Molten State:
When NaCl is heated to a sufficiently high temperature, it melts and becomes a molten liquid. In the molten state, the electrostatic forces holding the ions in fixed positions are overcome, and the ions gain enough energy to move freely. Consequently, molten NaCl can conduct electricity because the ions are mobile and can carry an electric current.

In summary, the difference in the conductivity of NaCl in different states is attributed to the mobility of ions. In the solid state, the ions are fixed in a lattice structure and cannot move, whereas in the aqueous solution and molten state, the ions become mobile, allowing for the conduction of electricity.