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Metals and Non-Metals — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceMetals and Non-Metals3 Marks
Question
Zn is more electropositive than Fe. Therefore, it should get corroded faster than Fe. But it does not happen. Instead, it is used to galvanize iron. Explain why does it happen so?
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Answer

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.

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