Question

Name and describe the most widely used method for refining impure metals?

Answer 1

Electrolytic Refining

The most widely used method for refining impure metals is electrolytic refining.

Description:

Electrolytic refining is a process used to obtain high-purity metals from impure metals, based on the principle of electrolysis.

Setup:

• Anode: Thick block of impure metal
• Cathode: Thin strip of pure metal
• Electrolyte: Solution of a soluble salt of the metal being refined

Process:

• At the Anode (Impure Metal): Metal atoms lose electrons and enter the solution as ions: \[ M_{\text{(impure)}} \rightarrow M^{n+}_{\text{(aq)}} + ne^- \]
• Movement: \( M^{n+} \) ions from the solution move toward the cathode.
• At the Cathode (Pure Metal): Metal ions gain electrons and deposit as pure metal: \[ M^{n+}_{\text{(aq)}} + ne^- \rightarrow M_{\text{(pure)}} \]

Impurities:

• Soluble Impurities: Dissolve in the electrolyte
• Insoluble Impurities: Settle below the anode as anode mud, which may contain valuable metals like gold, silver, platinum

Effective For:

This method refines metals such as copper, zinc, tin, nickel, silver, and gold to a high degree of purity.

Summary Table:

\[ \begin{array}{|l|l|} \hline \textbf{Process} & \textbf{Reaction} \\ \hline \text{Anode (Impure Metal)} & M \rightarrow M^{n+} + ne^- \quad \text{(Oxidation)} \\ \text{Cathode (Pure Metal)} & M^{n+} + ne^- \rightarrow M \quad \text{(Reduction)} \\ \text{Soluble Impurities} & \text{Remain in electrolyte} \\ \text{Insoluble Impurities} & \text{Settle as anode mud (e.g., Au, Ag, Pt)} \\ \hline \end{array} \]