Question

The process of cementation involves:

• A. Elimination of a more reactive metal from molten metal by preferential oxidation
• B. Refining by preferential dissolution of the desired metal in an organic solvent
• C. Extraction by selective dissolution of the desired metal in an inorganic solvent
• D. Separation of the desired metal by adding a more reactive metal

Hint:

Cementation purifies metals by \textbf{removing more reactive elements}, especially via \textbf{preferential oxidation} in molten phases.

Answer 1

The Correct Option is A

Step 1: Understanding Cementation
Cementation is a metallurgical purification process where a more reactive metal is removed or precipitated from a solution or molten phase by chemical displacement or oxidation. In hydrometallurgy, cementation is often used to: - Eliminate more reactive metals through selective oxidation, - Recover less reactive metals like copper by using zinc as a sacrificial metal. Step 2: Mechanism of Cementation
A more reactive metal is oxidized: \[ \text{M}^{0}_{\text{more reactive}} \rightarrow \text{M}^{n+} + ne^- \] This displaces a less reactive metal from its ionic form: \[ \text{M}^{n+}_{\text{less reactive}} + ne^- \rightarrow \text{M}^{0} \] However, when considering molten metal, cementation implies selective oxidation to remove more reactive impurities. Step 3: Clarifying the Misleading Options
- (B) and (C) refer to solvent extraction processes, not cementation.
- (D) misstates the process — in cementation, the more reactive metal is removed, not the desired metal added. Conclusion: Cementation in molten systems involves elimination of more reactive metals via preferential oxidation.