Question

Explain what Galvanization is. What purpose is served by it?

Answer 1

Iron in presence of oxygen and moisture present in the air, undergoes corrosion. A layer of ferric oxide is formed. To prevent rusting of iron, a layer of zinc can be applied on iron. Zinc provides cathodic protection as zinc acts as an anode and gets corroded instead of iron. Corrosion is a redox reaction. Iron undergoes oxidation, there is an increase in oxidation state and electrons are lost.

Complete step by step solution:
-When iron is exposed to oxygen in presence of moisture, rust is formed on the surface.
-Corrosion is not instantaneous, it occurs gradually over time. Oxygen atoms form a bond with iron atoms which lead to the formation of iron oxides.
-The bond between iron atoms is weakened due to this.
-Corrosion is a redox reaction. Iron undergoes oxidation, there is an increase in oxidation state and electrons are lost.
-Oxygen is a very good oxidizing agent and iron is a reducing agent, so iron readily gives electrons to oxygen.
-Rusting weakens iron, degrades its appearance and strength. Rusting can damage automobiles, grills etc.
-Rusting can be prevented by applying a thin layer of paint.
-Most commonly used method to prevent rusting of iron is galvanization.
-In galvanization, a protective layer of zinc is applied on metal.
- It can be achieved by dipping iron in hot, molten zinc by the process of electroplating.
-as zinc has more tendency to undergo oxidation than iron, it acts as anode and provides protection to iron also known as cathodic protection. zinc is corroded instead of iron.
-Galvanization is the process of the applied protective layer of zinc to metal such as iron and it serves the purpose of protecting iron from oxygen and preventing corrosion.

Note: other methods to prevent iron from rusting are cathodic protection, coating etc. Disadvantages of galvanization are it provides protection for a limited time. It is not effective in highly corrosive areas. factors affecting rusting of iron are moisture, acid, salt and impurity. rusting is accelerated in humid conditions. Zinc provides cathodic protection as zinc acts as an anode and gets corroded instead of iron.