Problem 165 - A Complete Resource Book in Chemistry for JEE Main

Question

Among \(\mathrm{Zn}, \mathrm{Cd}, \mathrm{Cu}, \mathrm{Sn}, \mathrm{Ge}, \mathrm{Pb}, \mathrm{Au}\) and \(\mathrm{Bi}\), no. of metals refined by liquation is

Step-by-Step Solution

Answer

3 metals are refined by liquation: Sn, Pb, and Bi.

Step 1: Understanding Liquation

Liquation is a metallurgical technique that uses the low melting point of metals to separate them from less fusible materials. It is often used for metals that can have a melting point that is still higher than impurities or other unwanted substances.

Step 2: Identifying Suitable Metals

Among the metals given, liquation is typically used for metals that need to be separated from alloys or less fusible components. In general, metals such as tin (Sn), lead (Pb), and bismuth (Bi) can be refined using this technique due to their relatively low melting points.

Step 3: Listing Metals Refined by Liquation

Given the properties of each metal mentioned - 1. Zinc (Zn): Higher melting point. 2. Cadmium (Cd): Not typically refined by liquation. 3. Copper (Cu): Higher melting point. 4. Tin (Sn): Suitable. 5. Germanium (Ge): Not typically refined by liquation. 6. Lead (Pb): Suitable. 7. Gold (Au): Higher melting point. 8. Bismuth (Bi): Suitable. The metals that align with the liquation method are Tin (Sn), Lead (Pb), and Bismuth (Bi).

Step 4: Calculating the Number of Metals

Counting the metals listed in the previous step that are refined by liquation gives us three: Tin (Sn), Lead (Pb), and Bismuth (Bi).

Key Concepts

Liquation

Liquation is a remarkable metallurgical technique designed to harness the property of variable melting points among different metals. To put it simply, liquation capitalizes on the fact that some metals have lower melting points compared to others. This process enables the separation of these metals from alloys or materials that are less fusible.
For instance, imagine you have a mixture where one metal melts easily and the other doesn't. Liquation allows you to selectively melt and pour off the easily melted metal, leaving the less fusible metal behind.
From the practical aspect, this technique is particularly useful when specific metals need refining. It is an indispensable tool in metallurgy, allowing industries to purify metals in a cost-effective and efficient manner.

• Liquation is optimal for metals with significantly lower melting points
• It requires careful temperature management to avoid melting unwanted materials
• Used especially in historical metalworking and continues to be relevant in modern practices

Metals with Low Melting Points

Certain metals are classified as having low melting points, making them ideal candidates for liquation. Typically, these metals melt at temperatures that are less intense compared to other metallic elements. The key metals often associated with this characteristic include tin (Sn), lead (Pb), and bismuth (Bi). These metals are less energy-intensive to process due to their lower heat requirements.
Understanding the properties of these metals is crucial for their utilization:

• Tin (Sn): Known for its characteristic silvery-white appearance, it melts at just about 232 °C. Tin is often used in soldering, coatings, and various alloys.
  
• Lead (Pb): Exhibits a bluish-gray color and has a relatively low melting point of 327.5 °C. Used in batteries, radiation shields, and other industrial applications.
  
• Bismuth (Bi): Recognized for its brittle nature and distinctive iridescence, melting at 271.4 °C. Valued in cosmetics, medicine, and atomic research.
  

The lower melting points of these metals make them particularly suitable for the liquation process, enabling efficient extraction and purification.

Metal Refining

Metal refining is the process of purifying an impure metal extracted from ores to obtain a semi-finished product or pure metals. Metallurgical techniques like liquation are crucial in the refinement process. They help remove undesirable materials, aiming to achieve desired properties in the final product.
Refining processes vary significantly depending on the metal being purified. Liquation is just one method among several, yet its specificity for metals with low melting points grants it a unique position in the refining world.

• The primary goal is to eliminate impurities and increase metal purity
• Refworkquently used techniques incluences commonly used techniques include electrorefining, pyrometallurgical processes, and hydrometallurgical approaches
• Highly regulated to ensure environmental and safety standards are met during metallurgical processes

Through methods like liquation, metallurgists can efficiently transform raw materials into high-quality metals, ready for use in various industrial and commercial applications.