Problem 180 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

Galvanization is applying a coating of  ext{Zn} ext{ (zinc).

Step 1: Understanding Galvanization

Galvanization is a process where a metal is coated with another layer to prevent rusting and corrosion. It is commonly used to protect steel or iron articles from rusting by applying a layer of some other metal.

Step 2: Identifying the Metal Used

The metal typically used in galvanization is zinc ( ext{Zn} ext{). This is because zinc serves as a sacrificial anode, meaning it will preferentially corrode, thereby protecting the base metal from rust.

Step 3: Choosing the Correct Answer

Among the options provided, the metal that is typically applied during galvanization is zinc ( ext{Zn} ext{). The other metals like copper ( ext{Cu} ext{), chromium ( ext{Cr} ext{), and lead ( ext{Pb} ext{) are not used for this purpose.

Key Concepts

Corrosion Prevention

Corrosion is a natural process that gradually deteriorates metals due to chemical reactions with environmental elements like air and moisture. It is a significant concern for metal structures, leading to damage, failure, and increased repair costs.

Preventing corrosion is crucial for prolonging the lifespan of metal objects. One effective method is galvanization, which involves applying a protective coating to the metal, preventing it from direct exposure to corrosive elements.

• Protective coatings block moisture and air from contacting the metal surface, thus preventing rust.
• These coatings can be made from various materials, but zinc is preferred due to its unique properties.

Employing effective corrosion prevention strategies like galvanization ensures safety, saves resources, and extends the utility of metal structures.

Zinc Coating

During the galvanization process, a thin layer of zinc is applied to the surface of steel or iron. This zinc coating is pivotal in protecting metal surfaces from corrosion.

The zinc layer serves two primary purposes:

• First, it acts as a barrier that physically separates the base metal from the elements that can cause corrosion, like moisture and oxygen.
• Second, zinc provides sacrificial protection. If the surface layer of zinc is scratched or damaged, it still protects the underlying metal.

Zinc coating is highly effective and extensively used in various industries, making it one of the most popular methods for corrosion protection.

Sacrificial Anode

A fascinating concept in galvanization is the role of zinc as a sacrificial anode. In this context, a sacrificial anode is a metal that is more reactive to corrosion than the metal it is protecting. Zinc, when used in galvanization, is intentionally allowed to corrode instead of the metal it covers, such as iron or steel.

Here's how it works:

• When the metal coating undergoes any wear or injury, exposing parts of the base metal, the zinc oxidizes first because it is more reactive.
• This process is known as cathodic protection, where zinc acts as an anode, protecting the cathode metal underneath.
• Even when compromised, the zinc continues to corrode and provides lasting protection to the base metal.

This sacrificial nature of zinc makes it an integral part of the effective protection system provided by galvanization, making sure the base structure remains intact over time.