1. Rusting process

2. Rusting process

3. Necessary conditions of Rusting
Presence of oxygen (or air)
Presence of water

4. Rusting process

5. Rusting process

6. Conditions that accelerate rusting
Presence of a strong electrolyte (e.g. salt solution - a good conductor)
Presence of a less reactive metal e.g Sn, Cu
Presence of acid
Bent or Sharp angled iron article
The speed of rusting can
be monitored by a yellow
rust indicator which will turn blue in the presence of rust (Fe2+(aq) ion).

7. Presence of strong electrolyte (e.g. sea water)
Strong electrolyte enhances the conductivity of the solution and speeds up the rusting process.

8. Presence of less reactive metal (e.g. Sn, Zn)
A scratched tin-plated iron can rusts more quickly than an ordinary iron can.

9. Presence of less reactive metal (e.g. Sn, Cu)

10.  Why does a scratched tin-plated iron can rust more quickly than an ordinary iron can ?
As tin is less reactive than iron, iron will lose electrons through tin at a faster speed than if tin is absent. Therefore, the can will rust more quickly.

11. Presence of acid
In the presence of acid, Fe(s) forms Fe2+(aq) ions more readily and rusts faster.
Fe(s) + 2H+(aq)  Fe2+(aq) + H2(g)

12. Conditions accelerate rusting
Presence of a strong electrolyte (e.g. salt solution - a good conductor)
Presence of a less reactive metal e.g Sn, Cu
Presence of acid
Bent or Sharp angled iron article
The speed of rusting can
be monitored by a yellow
rust indicator which will turn blue in the presence of rust (Fe2+(aq) ion).