* Water is preferentially electrolyzed: When you apply electricity to an aqueous solution of sodium chloride, water molecules are more readily electrolyzed than the chloride ions. This leads to the formation of hydrogen gas at the cathode and oxygen gas at the anode, rather than sodium and chlorine.
* Safety Concerns: Electrolyzing water in an aqueous solution of sodium chloride produces hydrogen and chlorine gases. Hydrogen is flammable and chlorine is toxic, making this process very dangerous.
Why molten sodium chloride is used instead:
* No water interference: By using molten sodium chloride (NaCl), you eliminate water from the system, preventing it from being electrolyzed. This allows the chloride ions to be electrolyzed, producing chlorine gas at the anode.
* Direct metal production: The sodium ions are also reduced at the cathode, producing liquid sodium metal.
In summary: Using molten sodium chloride for electrolysis ensures:
* Direct production of sodium metal and chlorine gas.
* Safety due to the absence of flammable and toxic gases.
This process is known as the Downs process, and it is the primary industrial method for producing sodium metal.
