Question

Refining of silver is done by

• A. Liquation
• B. Cupellation
• C. Poling
• D. Van Arkel method

Hint:

Associate specific refining processes with key metals:

• Cupellation \(\rightarrow\) Silver (Ag), Gold (Au) from Lead (Pb)

• Parke's Process \(\rightarrow\) Silver (Ag) from Lead (Pb) using Zinc (Zn)

• Poling \(\rightarrow\) Copper (Cu) to remove Oxygen

• Mond Process \(\rightarrow\) Nickel (Ni)

• Van Arkel Method \(\rightarrow\) Titanium (Ti), Zirconium (Zr)

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The question asks for a specific refining process used for silver. Refining is the purification of an impure metal. Different methods are used based on the chemical and physical properties of the metal and its impurities.

Step 2: Detailed Explanation:

• (A) Liquation: This method separates metals with different melting points. It is used for metals with low melting points like tin or lead, but not for silver.

• (B) Cupellation: This is a high-temperature refining process used for separating noble metals, like gold and silver, from base metals like lead, copper, and zinc. The process relies on the principle that noble metals do not oxidize, whereas base metals do. When argentiferous lead (lead containing silver) is melted in a porous cupel and a blast of air is directed over it, the lead oxidizes to litharge (PbO), which is either absorbed by the cupel or skimmed off, leaving behind a bead of pure silver. This is a primary method for silver refining.

• (C) Poling: This is a refining method used specifically for removing oxygen from molten blister copper. It involves stirring the molten metal with poles of green wood. It is not used for silver.

• (D) Van Arkel method: This is a vapor-phase refining process for producing ultra-high purity metals, particularly reactive metals like titanium and zirconium. It is not used for silver.


Step 3: Final Answer:
Cupellation is the standard and historical method for refining silver, particularly for separating it from lead.