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

Question

Parke's process is used (a) to extract Cu using \(\mathrm{CuFeS}_{2}\) (b) to extract Ag from argenti ferrous lead (c) to extract \(\mathrm{Ag}\) by forming amalgam (d) to extract \(\mathrm{Ag}\) using \(\mathrm{NaCN}\)

Step-by-Step Solution

Answer

Parke's process is used to extract Ag from argenti ferrous lead (option b).

Step 1: Understanding Parke's Process

Parke's process is a metallurgical method used for the desilverization of lead. This involves the removal of silver from lead bullion by utilizing the formation of an insoluble argentiferous zinc crust.

Step 2: Identifying Parke's Process Application

Since Parke's process directly involves silver, it is used to extract silver from lead that contains silver impurities, specifically from argentiferous (silver-containing) lead.

Step 3: Matching With Given Options

Option (b) 'to extract Ag from argenti ferrous lead' corresponds directly to the function of Parke's process, as it involves extracting silver from lead that has silver (argenti) content.

Key Concepts

Parke's process

Parke's process is a fascinating metallurgical procedure developed to purify lead by removing its silver content. This method takes advantage of the differing solubility properties of silver and lead when in contact with zinc.
During the process, zinc is added to molten lead containing silver. Zinc has the property of forming an alloy with silver more readily than with lead. Thus, when it is mixed in, zinc attracts silver, forming a crust on the surface. This crust consists mostly of silver and zinc, sometimes with little lead.
Once this crust solidifies, it can be skimmed off easily, leaving behind mostly pure lead. The separated crust can then be processed further to extract pure silver.

Desilverization

Desilverization refers to the process of removing silver impurities from another metal, most commonly lead. Parke's process is a primary example of this concept, where the end goal is to purify argentiferous lead by stripping away its silver content.
The efficiency of desilverization greatly depends on the correct implementation of Parke's process. The right amount of zinc for the quantity of silver must be calculated; otherwise, some silver might be left unextracted, or excess zinc could result in unnecessary expense and waste.
This metallurgical technique is vital in industries where high-purity lead is essential, like in the production of batteries and radiation shielding.

Argentiferous lead

Argentiferous lead is a term used to describe lead that contains silver impurities. This kind of lead is commonly found in nature, where silver is often intertwined with lead ores.
Historically, argentiferous lead was both a problem and a boon. While it necessitated additional processing to separate out the valuable silver, it also provided an opportunity to harness both metals from a single source.
Using processes like Parke's, the valuable silver can be economically extracted from this type of lead, turning what might be an impurity in some contexts into a sought-after metal.

Extracting silver from lead

The concept of extracting silver from lead is central to certain metallurgical processes. In the context of lead purification, silver is considered an impurity that must be removed.
Parke's process revolutionized this extraction by providing an efficient method to separate these metals. Initially, raw argentiferous lead is melted down, and zinc is introduced. Silver, being more soluble in zinc than in lead, moves to the zinc, forming a crust that can be removed.

• This extraction process makes the initial step of refining more productive and lucrative, especially in mines where silver-laden lead is abundant.
• The remaining lead becomes suitable for various applications where high purity is required.

Understanding the basics of extracting silver from lead allows us to appreciate the sophistication of older technologies and their role in modern metallurgy.