Question

The most durable metal plating on iron to protect against corrosion is:
a.) Tin plating
b.) Zinc plating
c.) Copper plating
d.) Nickel plating

Answer 1

Hint: Iron in presence of oxygen and moisture present in air, undergoes corrosion. A layer of ferric oxide is formed. Zinc has higher standard oxidation potential than Iron. Tin, copper and nickel have lower oxidation potential than iron. Corrosion is a redox reaction. Iron undergoes oxidation, there is increase in oxidation state and electrons are lost

Complete step by step answer:
-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 bonds with iron atoms which leads to 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.
-Zinc has higher standard oxidation potential than Iron. Tin, copper and nickel have lower oxidation potential than iron.
-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.
The most durable metal plating on iron to protect against corrosion is The most durable metal plating on iron to protect against corrosion is Zinc plating
So, the correct answer is “Option B”.

Note: Zinc has higher standard oxidation potential than Iron. Tin, copper and nickel have lower oxidation potential than iron. 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.