Problem 10 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Galvanization is applying a coating of: (a) \(\mathrm{Cu}\) (b) \(\mathrm{Zn}\) (c) \(\mathrm{Pb}\) (d) \(\mathrm{Cr}\)

Step-by-Step Solution

Answer

Galvanization applies a coating of Zinc (\(\mathrm{Zn}\)).

Step 1: Understanding Galvanization

Galvanization is the process of applying a protective zinc coating to steel or iron to prevent rusting.

Step 2: Identify the Correct Element

Among the given options—Copper (\(\mathrm{Cu}\)), Zinc (\(\mathrm{Zn}\)), Lead (\(\mathrm{Pb}\)), and Chromium (\(\mathrm{Cr}\))—identify the element commonly used in galvanization.

Step 3: Matching Element to Use

The element commonly used in galvanization is Zinc (\(\mathrm{Zn}\)). Galvanized steel is coated with a layer of zinc to help protect it from corrosion.

Key Concepts

Zinc coating

A zinc coating is a crucial part of the galvanization process, which involves applying a thin layer of zinc to a metal surface—usually steel or iron. This layer serves as a barrier to protect the underlying metal from environmental elements that cause rust and corrosion. The zinc layer is applied through various methods, including hot-dip galvanizing, electro-galvanizing, and zinc spraying.

- **Hot-dip galvanizing** involves immersing the metal in a bath of molten zinc, creating a strong bond between the zinc and the metal. - **Electro-galvanizing** uses an electric current to deposit a zinc coating on the metal, allowing for a more controlled and uniform layer. - **Zinc spraying**, or metallizing, involves spraying molten zinc onto the metal surface through a spray gun.

These coatings vary in thickness and can be adapted based on the required level of protection and application environment. This flexibility makes the zinc coating a versatile method for providing a reliable protective layer.

Corrosion prevention

Corrosion prevention is the main objective of galvanization. Corrosion is the gradual degradation of metal due to chemical reactions with environmental elements such as oxygen and moisture. Without protection, metals like iron or steel tend to rust, compromising their strength and longevity.

Zinc is particularly effective as a preventive measure because it acts as a sacrificial anode. When the zinc-coated metal comes into contact with moisture, the zinc corrodes preferentially over the base metal. This sacrifices the zinc layer, preserving the core metal beneath from rusting.

The longevity of the protection offered by zinc depends on factors like coating thickness, exposure to pollutants, and physical abrasion. Other methods of corrosion prevention can include:

• Paint coatings
• Plastic coatings
• Regular maintenance and inspections

Galvanization remains a preferred method due to its cost-effectiveness and long-lasting protection.

Zinc protection

Zinc protection refers to the protective role that zinc plays in safeguarding metals against corrosion. The virtue of zinc protection is not just limited to forming a physical barrier; it also offers a form of electrochemical protection. This dual-protective ability makes zinc an ideal choice for guarding valuable infrastructure.

When the zinc layer is intact, it serves as a robust barrier preventing water and air from reaching the underlying metal. If the zinc layer is scratched or damaged, zinc's "sacrificial" properties come into play. Zinc will corrode in lieu of the metal beneath it, thereby preventing rust from forming on the core metal.

Key advantages of zinc protection include:

• Prolonged lifespan of steel structures
• Resistance to various environmental conditions
• Aesthetic finish with less maintenance required

Overall, zinc protection provides reliable and cost-effective means of extending the durability of metals, making it an essential component of modern protective practices in construction and manufacturing.