Which of the following is the most effective method to prevent the corrosion of iron structures in highly sali

Question

Which of the following is the most effective method to prevent the corrosion of iron structures in highly saline coastal environments?

Examoogle · Accepted Answer

The correct answer is Option B: Galvanization. Galvanization coats iron with a layer of zinc, which acts as a sacrificial anode and protects the underlying iron from corrosion.

Step-by-Step Solution & Concepts:
Galvanization coats iron with a layer of zinc, which acts as a sacrificial anode and protects the underlying iron from corrosion.

Working Principle: Zinc, being more electro‑positive than iron, preferentially oxidises ($Zn \rightarrow Zn^{2+} + 2e^{-}$). The released electrons flow to the iron surface, preventing its oxidation ($Fe \rightarrow Fe^{2+} + 2e^{-}$) and thus inhibiting rust formation, especially in chloride‑rich sea‑air.

Key Formulas: $Zn \rightarrow Zn^{2+} + 2e^{-}$ — oxidation of zinc (sacrificial); $Fe \rightarrow Fe^{2+} + 2e^{-}$ — corrosion of iron

Key Points: Zinc has a more negative electrode potential than iron.; The zinc coating provides both barrier protection and sacrificial protection.

Advantages: Long‑lasting protection (10–20 years).; Effective in highly corrosive, salty environments.

Disadvantages: Initial cost higher than simple painting.; If the coating is damaged, corrosion can start at the exposed spot.

Applications: Marine structures, ship hulls, offshore platforms.; Bridges, steel water pipelines, automobile chassis.

Additional Info: Standard hot‑dip galvanizing uses ~0.5 mm zinc coating.. Option A (painting) merely slows corrosion and can fail quickly in salty spray.

Answer: B is correct — galvanization provides sacrificial protection that outperforms painting in saline conditions.

Exam Tip: Remember that the metal with the lower (more negative) standard electrode potential acts as the sacrificial anode, so zinc protects iron.

Examoogle · Answer

Option A: Painting the iron surface

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Option C: Simple oiling

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Option D: Storing in a humid chamber

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