Final answer:
During electrolysis, Na+ ions are not reduced to metallic sodium because they are difficult to reduce compared to water; water undergoes reduction instead. Cl- ions are oxidized to form Cl2 gas. The solubility and dissociation of NaCl in water contribute to the conductivity of the solution due to the ionization process.
Step-by-step explanation:
During electrolysis, Na+ ions do not naturally gain electrons to form metallic sodium because they are more challenging to reduce than the water molecules present in the solution. Instead, water molecules at the negative electrode gain electrons during the reduction half of the reaction, leading to the formation of hydrogen gas and hydroxide ions. Cl− ions, on the other hand, are oxidized at the positive electrode and release electrons to form chlorine gas (Cl2).
When NaCl dissolves in water, the Na+ and Cl− ions separate and can freely move, which increases the water's conductivity. The separation of ions is due to the interaction between the ions and the partial positive and negative charges of water molecules, which is stronger than the ionic bond in the solid NaCl. This ionization process leads to the formation of an electrolyte solution, which conducts electricity because of the presence of these free-moving ions.
The conductivity of such a solution varies depending on the concentration of ions; higher concentrations of ions result in better conductivity. Soluble salts like NaCl readily dissolve and ionize, contributing to this conductivity. In contrast, weak electrolytes like HgCl2, which do not produce many ions, conduct electricity poorly due to the low concentration of ions in the solution.