What is meant by 'rusting' ? With labelled diagrams, describe an activity to find out the conditions under which iron rusts.

Explanation

Rusting is corrosion of iron to a brown flaky substance in the presence of moist air. Activity to find out the conditions under which iron rusts:
1. Take three test tubes and place clean iron nails in each of them.
2. Label these test tubes as A, B and C.
3. Pour some water in test tube A and cork it
4. Pour boiled distilled water in test tube B, add about 1 mL of oil and cork it. The oil will float on water and prevent air from dissolving in water.
5. Put some anhydrous calcium chloride in test tube C and cork it. Anhydrous calcium chloride will absorb the moisture, if any, from the air. Leave the three test tubes for a few days and then observe. Observation: The iron nails in test tube A rusts. In test tubes B and C, no rusting occurs.
Conclusion: Both air and moisture are necessary for rusting of iron.