1. Dissolution: When sodium chloride (NaCl) dissolves in water, it dissociates into its constituent ions: sodium ions (Na+) and chloride ions (Cl-). This is due to the strong electrostatic attraction between water molecules and the ions, which overcomes the attraction between the Na+ and Cl- ions in the solid crystal.
2. Ion Mobility: These ions are now free to move throughout the solution. When a voltage is applied across the solution, the positively charged sodium ions (Na+) move towards the negative electrode (cathode), and the negatively charged chloride ions (Cl-) move towards the positive electrode (anode).
3. Electric Current: This movement of charged ions constitutes an electric current. The more ions present in the solution, the stronger the conductivity.
In contrast: Pure water itself is a very poor conductor of electricity because it contains very few free ions.
Key takeaway: The presence of free ions, created by the dissociation of the solute, is the key factor that allows an aqueous solution of sodium chloride to conduct electricity.
