Briefly explain how zinc protects iron when used as a galvanised coating.
Answer
Zinc acts as a sacrificial anode; it corrodes first, thereby protecting the underlying iron.
The correct answer is Zinc acts as a sacrificial anode; it corrodes first, thereby protecting the underlying iron. — When zinc is exposed to the environment it oxidises (zinc → Zn²⁺ + 2e⁻), protecting the iron underneath.
Step-by-step solution
- Zinc has a higher reduction potential than iron, so it acts as a sacrificial anode.
- When zinc is exposed to the environment it oxidises (zinc → Zn²⁺ + 2e⁻), protecting the iron underneath.
Common mistake: Forgetting that zinc corrodes preferentially
Concept tested: Sacrificial anode protection
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