Question:
Protecting steel and iron from rusting by coating them with a thin layer of zinc is called:
Protecting steel and iron from rusting by coating them with a thin layer of zinc is called:
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Galvanization uses Zinc (\(Zn\)) because of its sacrificial protection property.
Even if the zinc layer is scratched, the iron underneath remains protected because zinc oxidizes more readily than iron.
Even if the zinc layer is scratched, the iron underneath remains protected because zinc oxidizes more readily than iron.
Updated On: Jul 13, 2026
- Tinning
- Galvanisation
- Electroplating
- Anodising
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Question:
The question asks for the name of the metallurgical protective process where steel or iron is coated with a thin layer of zinc to prevent corrosion (rusting).
Step 2: Key Formula or Approach:
Corrosion protection methods physically isolate the metal from oxygen and moisture, or use sacrificial protection. Zinc acts as a sacrificial anode.
Step 3: Detailed Explanation:
• Iron and steel rust when exposed to moist air containing oxygen and water vapor:
\[ 4Fe + 3O_2 + 2xH_2O \to 2Fe_2O_3 \cdot xH_2O \text{ (Rust)} \] - To prevent this, various barrier methods are used.
• Galvanization is the process of applying a protective zinc coating to steel or iron.
• The thin zinc layer acts in two protective ways:
1. Barrier Protection: It physically blocks oxygen and water from reaching the iron underneath.
2. Sacrificial Protection: Since zinc is more reactive than iron, even if the zinc coating is scratched or damaged, the zinc will corrode preferentially (sacrificing itself) to protect the underlying iron.
• Let us analyze the other options:
- (A) Tinning: The process of coating iron with a layer of tin. Tin is less reactive than iron, so if the coating is damaged, the iron underneath rusts even faster.
- (C) Electroplating: A general method of depositing a layer of any metal on another surface using electricity. Galvanization is a specific type of zinc coating, often done by hot-dip galvanizing.
- (D) Anodising: The process of forming a thick oxide layer on aluminum to protect it from corrosion, not steel or iron.
• Thus, the correct name for coating iron with zinc is galvanisation.
Step 4: Final Answer:
The process of coating iron with zinc is called Galvanisation.
The question asks for the name of the metallurgical protective process where steel or iron is coated with a thin layer of zinc to prevent corrosion (rusting).
Step 2: Key Formula or Approach:
Corrosion protection methods physically isolate the metal from oxygen and moisture, or use sacrificial protection. Zinc acts as a sacrificial anode.
Step 3: Detailed Explanation:
• Iron and steel rust when exposed to moist air containing oxygen and water vapor:
\[ 4Fe + 3O_2 + 2xH_2O \to 2Fe_2O_3 \cdot xH_2O \text{ (Rust)} \] - To prevent this, various barrier methods are used.
• Galvanization is the process of applying a protective zinc coating to steel or iron.
• The thin zinc layer acts in two protective ways:
1. Barrier Protection: It physically blocks oxygen and water from reaching the iron underneath.
2. Sacrificial Protection: Since zinc is more reactive than iron, even if the zinc coating is scratched or damaged, the zinc will corrode preferentially (sacrificing itself) to protect the underlying iron.
• Let us analyze the other options:
- (A) Tinning: The process of coating iron with a layer of tin. Tin is less reactive than iron, so if the coating is damaged, the iron underneath rusts even faster.
- (C) Electroplating: A general method of depositing a layer of any metal on another surface using electricity. Galvanization is a specific type of zinc coating, often done by hot-dip galvanizing.
- (D) Anodising: The process of forming a thick oxide layer on aluminum to protect it from corrosion, not steel or iron.
• Thus, the correct name for coating iron with zinc is galvanisation.
Step 4: Final Answer:
The process of coating iron with zinc is called Galvanisation.
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