Problem 90 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following statements is incorrect? (a) lead is refined by electrolysis of \(\mathrm{PbSiF}_{6}\). (b) red lead \(\left(\mathrm{Pb}_{3} \mathrm{O}_{4}\right)\) is known as minium (c) yellow lead oxide (PbO) is known as massicot. (d) none of these

Step-by-Step Solution

Answer

Statement (a) is incorrect.

Step 1: Understand the Statements

Read through each statement to identify what each is describing. We have: (a) Lead refining through electrolysis of \( \mathrm{PbSiF}_{6} \). (b) Red lead (\( \mathrm{Pb}_{3} \mathrm{O}_{4} \)) is known as minium. (c) Yellow lead oxide (PbO) is referred to as massicot. (d) None of these statements are incorrect.

Step 2: Evaluate Statement (a)

Statement (a) claims that lead is refined by electrolysis of \( \mathrm{PbSiF}_{6} \). Lead is typically refined by a variety of methods, but electrolysis of \( \mathrm{PbSiF}_{6} \) is not a common or standard method for lead refining.

Step 3: Evaluate Statement (b)

Statement (b) says that red lead \( (\mathrm{Pb}_{3} \mathrm{O}_{4}) \) is known as minium. This is a correct statement because red lead is indeed known by the name 'minium'.

Step 4: Evaluate Statement (c)

Statement (c) indicates that yellow lead oxide (PbO) is known as massicot. This is also true because the yellow form of lead oxide is referred to as massicot.

Step 5: Evaluate Statement (d)

Statement (d) suggests that none of the other statements are incorrect. However, as confirmed in Step 2, statement (a) is the incorrect statement, so statement (d) is inaccurate.

Step 6: Identify the Incorrect Statement

After evaluating all the statements, we conclude that statement (a) is incorrect because the refining of lead by electrolysis of \( \mathrm{PbSiF}_{6} \) is not typically practiced.

Key Concepts

Lead Refining Methods

Lead refining is an important step in the production of high-purity lead materials. There are several methods used to refine lead, which are chosen based on the purity level needed and specific industrial applications. Generally, lead refining can be divided into pyrometallurgical and hydrometallurgical processes.

One common method is the Parkes process, a pyrometallurgical refining method that uses zinc to remove silver and gold from lead. This process improves the purity of the lead significantly. Another method is the Betts electrolytic process, which refines lead using an electrolytic cell and is effective for producing high-grade lead.

• Parkes Process: Uses zinc to separate impurities.
• Betts Process: Electrolytic process for high purity.

Electrolysis of lead hexafluorosilicate (\( \mathrm{PbSiF}_{6} \)) is not commonly used for lead refining. Instead, lead is usually refined with the Betts process or the Parkes process, ensuring cost-efficient and high-purity outcomes.

Red Lead (Minium)

Red Lead, chemically known as lead(II,IV) oxide or \( \mathrm{Pb}_{3} \mathrm{O}_{4} \), is commonly referred to as minium. This compound is well-known for its vibrant red color and significant industrial usage.

Red lead is a crucial material in the manufacturing of lead-acid batteries, where it is used in the positive plates. It is also used extensively as a pigment in paints and primers due to its corrosion-resistant properties. Red lead paints are especially utilized for protecting iron and steel structures.

• Used in lead-acid batteries.
• Prominent red pigment in paints.
• Provides corrosion resistance for metals.

The production of red lead involves heating lead monoxide (\( \mathrm{PbO} \)) in the presence of oxygen. This process yields \( \mathrm{Pb}_{3} \mathrm{O}_{4} \), adding oxygen ions to the lead monoxide structure.

Lead Oxide Varieties

Lead oxide exists in different forms, with their color and properties being distinct based on their chemical structure. The most common varieties of lead oxide are Litharge and Massicot, each with unique applications.

Litharge is the red form of lead(II) oxide (\( \mathrm{PbO} \)) and is stable under high-temperature conditions, often used in glass, ceramics, and enamel industries.

Massicot, the yellow form of lead(II) oxide, is also referred to simply as yellow lead oxide. This form is softer and is used in the manufacture of ceramics and as a flux in the preparation of glazes.

• Litharge: Red form, used in high-temperature applications.
• Massicot: Yellow form, soft, used in ceramics.

Understanding these varieties helps in selecting the appropriate type of lead oxide for specific industrial processes.