Chemistry 2010 JAMB Past Questions - Question 24: Iron can be protected from corrosion by coating the surface with

Correct Answer

D

Explanation

There are several effective methods for protecting iron from corrosion by coating its surface, each with its own advantages and disadvantages depending on the specific application:

**1. Galvanization:** This is the most common method, involving coating the iron with a thin layer of zinc. Zinc is more easily oxidized than iron, so it acts as a sacrificial anode, corroding first and protecting the underlying iron. This method is relatively inexpensive and effective for long-term protection.

**2. Tinning:** Similar to galvanization, tinning involves coating the iron with a layer of tin. This method is often used for food containers as tin is non-toxic and imparts a shiny appearance. However, tin is softer than zinc and may be more susceptible to scratches and wear.

**3. Painting:** Applying paint forms a barrier between the iron and the corrosive environment. The effectiveness depends on the specific type of paint and its proper application. Primers and corrosion-resistant paints offer better protection.

**4. Enameling:** This process involves fusing a glass-like coating onto the iron surface at high temperatures. Enamels provide excellent protection and aesthetics but can be brittle and susceptible to chipping.

**5. Anodizing:** This electrochemical process creates a thin oxide layer on the iron surface, enhancing its corrosion resistance and offering some decorative options. However, it may not be effective for all applications.

**Choosing the right method:**

The best method for protecting iron from corrosion depends on several factors, including:

* **Type of iron:** Different iron alloys may have varying susceptibilities to corrosion.
* **Intended use:** The expected environment and level of exposure to corrosive factors will influence the choice.
* **Cost and aesthetics:** Different methods have varying costs and visual appeal.
* **Environmental regulations:** Some materials used in coatings may have environmental restrictions.

Consulting a corrosion expert or researching specific applications can help you choose the most suitable method for protecting your iron from corrosion.