Electrolytic Refining: Metals Not Processed

Electrolytic refining is a method used to purify metals. It involves using an electric current to reduce ions of the metal from an electrolyte solution onto a pure metal cathode. This process is most effective for metals that are moderately reactive.

The question asks which metal from the list is NOT refined using this technique. Let's examine the options:

• Copper (Cu): Commonly refined electrolytically. Impure copper acts as the anode, pure copper as the cathode, and copper sulfate solution as the electrolyte.
• Tin (Sn): Can be refined using electrolytic methods, although other methods are also used depending on purity requirements.
• Zinc (Zn): Often refined electrolytically, especially after being obtained from smelting processes.
• Sodium (Na): Sodium is a highly reactive alkali metal. It has a very low electrode potential. Due to its high reactivity, sodium is typically extracted by the electrolysis of its molten salts (like molten NaCl), not refined by electrolytic refining of the impure metal itself. The standard electrolytic refining setup is not suitable for such reactive metals.

Therefore, sodium is the metal that is NOT typically refined by electrolytic refining among the given choices.