1. The problem is to understand the electrolysis of a sodium chloride (NaCl) solution. 2. Electrolysis is a process that uses electrical energy to drive a non-spontaneous chemical reaction. 3. In an aqueous NaCl solution, the main species present are Na^+, Cl^-, H_2O, and OH^-. 4. At the cathode (negative electrode), reduction occurs. Water is reduced rather than Na^+ because water has a higher reduction potential: $$\text{Cathode reaction: } 2H_2O + 2e^- \rightarrow H_2 + 2OH^-$$ 5. At the anode (positive electrode), oxidation occurs. Chloride ions are oxidized to chlorine gas: $$\text{Anode reaction: } 2Cl^- \rightarrow Cl_2 + 2e^-$$ 6. The overall reaction is: $$2NaCl + 2H_2O \rightarrow 2NaOH + H_2 + Cl_2$$ 7. This means that during electrolysis of NaCl solution, hydrogen gas is produced at the cathode, chlorine gas at the anode, and sodium hydroxide remains in solution. 8. Important rules: - Electrolysis involves oxidation at the anode and reduction at the cathode. - The species with the lower reduction potential is reduced at the cathode. - The species with the lower oxidation potential is oxidized at the anode. This explains the products formed during electrolysis of aqueous NaCl solution.