11
Question Question 11
Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.
Rusting involves slow oxidation of iron in presence of air and moisture resulting in formation of hydrated iron [III] oxide called rust.
Iron + Oxygen ⟶ Iron [III] Oxide Hydrated Iron [III] Oxide [rust]
| Test Tube A | Test Tube B | Test Tube C | |
|---|---|---|---|
| Contents | Anhydrous calcium chloride | Boiled tap water with oil layer on top | Ordinary tap water |
| Condition present | Oxygen | Moisture | Moisture & oxygen |
| Condition absent | Moisture | Oxygen | Nil |
| Result | Iron nails do not rust | Iron nails do not rust | Iron nails rust |
| Conclusion | Moisture is essential for rusting | Oxygen is essential for rusting | Moisture and oxygen both are essential for rusting |