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A galvanized iron sheet is scratched right down to the bare iron. What still protects the iron?
AIron oxidizes before the zinc does
BPaint seals the scratch over again
CThe scratch fills with iron(III) oxide
DZinc oxidizes before the iron does
Answer & Solution
Correct answer: D. Zinc oxidizes before the iron does
1. Galvanizing coats the iron with a layer of zinc.
2. Zinc has the lower reduction potential of the two metals, which makes it the more active metal.
3. The more active metal is the one that gives up electrons first.
4. So even with bare iron exposed, the zinc corrodes and the iron is spared.
5. Saying iron goes first would make the coating pointless once it was scratched.
_Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 17.6 Corrosion_
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