Question

Iron does not rust even if the zinc coating is broken in a galvanized iron pipe. Give reasons.

Give reasons:

Iron does not rust even if zinc coating is broken in a galvanized pipe.

Answer 1

1. Anodic coating protects the base metal “sacrificially”. Corrosion ofiron does not enhance even on breaking “anodic coating” as it heals its film.
2. The iron, coating metal is at lower electrode potential than zinc base metal.
3. Galvanizing is a process of coating iron with thin coat of zinc to protect themfrom rusting.
4. The iron sheets are cleaned with dilute H₂SO₄, i.e., pickled, to remove impurities. In this process, NH₄Cl flux is used.
5. Molten zinc is maintained at 425-4300C, which causes iron and rusting, even if the zinc coating is broken in a galvanized iron pipe.

Answer 2

Iron does not rust even if the zinc coating is broken in a galvanised pipe because zinc is more reactive than iron. Zinc acts as a sacrificial metal and gets oxidised in preference to iron, thereby protecting iron from rusting even at the exposed part.