Problem 65 - A Complete Resource Book in Chemistry for JEE Main

Question

Parke's process is used (a) to extract Cu using CuFeS, (b) to extract \(\mathrm{Ag}\) from argenti ferrous lead (c) to extract Ag by forming amalgam (d) to extract \(\mathrm{Ag}\) using \(\mathrm{NaCN}\)

Step-by-Step Solution

Answer

(b) to extract Ag from argenti ferrous lead

Step 1: Understand the Context

Parkes process, also known as the Parkes desilverization process, is a metallurgical method used primarily to remove silver from lead bullion. It relies on the fact that silver is more soluble in zinc than in lead, allowing for the silver to separate from the lead by forming an alloy with zinc.

Step 2: Analyze Option (a)

Option (a) mentions extracting uu from CuFeS. This is not related to the Parkes process, as the Parkes process is primarily used for dealing with silver and lead rather than copper ores.

Step 3: Analyze Option (b)

Option (b) states Parke's process is used to extract g g from argenti ferrous lead. Argenti ferrous lead refers to lead containing silver, aligning with the process of removing silver from lead, which is exactly what the Parkes process does.

Step 4: Analyze Option (c)

Option (c) involves forming an amalgam to extract silver. Amalgamation is a different process which traditionally uses mercury to extract silver and gold, not specifically related to the Parkes process.

Step 5: Analyze Option (d)

Option (d) describes extracting g g using isplaystyleNaCN isplaystyleNaCN. This describes cyanidation, a different silver extraction process, rather than the Parkes process.

Step 6: Conclusion

Based on the analysis, the option that correctly describes the use of Parkes process is (b), since it is specifically used to remove silver from lead by adding zinc, allowing the silver to transfer from lead to zinc.

Key Concepts

Silver Extraction

The process of silver extraction involves several different methods depending on the composition of the ore or alloy being processed. A common method is the Parkes Process, which efficiently removes silver from lead through the use of zinc. Silver is more soluble in zinc, allowing it to separate from lead when an alloy is formed. This method takes advantage of the differing solubility properties of silver in zinc and lead.

Outside of the Parkes process, there are other silver extraction methods:

• Amalgamation: Using mercury to form an amalgam with silver.
• Cyanidation: Extracting silver with a sodium cyanide solution.

Each method has its specific use cases, but the Parkes Process remains a primary choice for extracting silver from lead.

Lead Bullion

Lead bullion refers to impure or raw lead that is often mixed with other elements, like silver. In metallurgical processes, refining lead bullion to obtain pure lead or recover other valuable metals such as silver is a common practice. Understanding the properties and composition of lead bullion is crucial to determining the appropriate method for metal recovery.

The Parkes process specifically addresses the separation of silver from lead bullion. By introducing zinc to the molten lead bullion, zinc attracts and dissolves the silver due to its higher solubility. As the solution cools, the silver-zinc alloy solidifies and can be skimmed off, isolating the silver.

Zinc Alloying

Zinc alloying is a critical step in the Parkes Process used for silver extraction. When zinc is mixed with lead bullion, it forms an alloy with any silver present, effectively separating the silver from the lead.

The basis for zinc alloying lies in the chemical properties of zinc. Silver is more soluble in zinc than in lead, allowing this method to efficiently extract silver.

• First, the molten lead bullion is mixed with zinc.
• The silver dissolves into the zinc, creating a silver-zinc alloy.
• This alloy can then be separated mechanically from the lead.

This simple, yet effective method is fundamental for extracting silver from lead, facilitating the recovery of this precious metal.

Metallurgical Methods

Metallurgical methods are processes used to extract or refine metals from their natural ore forms or mixed alloys. These methods vary depending on the metal being extracted and its natural state. Efficient recovery of metals typically hinges on understanding their chemical and physical properties.

In the context of the Parkes process, the metallurgical method revolves around the separation of silver from lead bullion by using zinc. This is one of many processes under the umbrella of metallurgy, which also includes others like smelting, electrolysis, and more.

• The process incorporates thermal and chemical reactions to alter and segregate elements.
• Choosing the appropriate method ensures better purity and recovery rates.

The continued development and optimization of metallurgical methods help in efficiently isolating valuable metals, minimizing waste and improving environmental sustainability.