Question

What causes rusting of iron? Design an activity to show the conditions needed for iron nails to rust.

Answer 1

The production of rust means, the Iron ($Fe$) on the surface of iron objects or structures reacts with moisture in the atmosphere in the presence of Oxygen ($O_2$). It is an oxidation reaction.

Rust is created by a redox reaction between Oxygen ($O_2$) and Iron ($Fe$) in a moist environment.

The activity to show the conditions needed for Iron nails to rust is given below.

Clean Iron ($Fe$) nails should be placed in each of the three test containers. These test tubes should be labeled, $A$, $B$, $C$ and $D$.

Test tube $A$ should be filled with deionized water.
There should be no Oxygen ($O_2$) in Test tube $B$ since it is filled with boiling water and an oil layer.

Regular tap water with Oxygen ($O_2$) is used in Test Tube $C$.
Calcium chloride ($CaC{l}_2$) is included in Test Tube $D$, which will dry the air.
Allow each test tube to sit for a few days after covering it. Compare the nail conditions in each test tube.

It is observed that the needles in test tube $A$ and $C$ start to corrode. There is no rust on the needles in test tube $B$. They don't get any rust in test tubes $C$ and $D$ either.

Hence, it is concluded that rust is formed when the iron is exposed to air and moisture.