Question

Zinc is more electropositive than Iron. Therefore, it should get corroded faster than iron.
But it doesn't happen. Instead, it is used to galvanide iron. Explain why does it happen so?

Answer 1

Yes zinc is most electropositive than iron but the idea behind zinc being used to galvanize iron is based on their electrode potentials. Zinc has most negative electrode reduction potential than iron. This implies that zinc will be more reactive than iron hence when used to galvanize iron it will be sacrificed in place of iron hence protecting the iron metal from being corroded. this idea forms the basis for sacrificial  protection.

Answer 2

Zinc is more electropositive than Iron but it does not get corroded faster and is used to galvanize iron.

Reasons:

• A thin layer prevents the entering of water and oxygen underneath.
• Zinc is more reactive than iron.
• Oxidizes in preference to the iron.
• Corrosion is because when oxygen in the air reacts with the surface of zinc.
• Dense and impermeable coating of zinc oxide.
• Acts as a physical barrier that protects the zinc surface.