Results:

(click on each item to see a pop-up large scale picture)

Write up: You should see some pretty conclusive results in this experiment, showing the quite devastating effect of salt on the process of corrosion.

Experiment A : The aluminium foil in fresh water is uncorroded, but the foil in salt water is full of holes and very brittle. It has corroded badly. You might have seen some cloudy white residue around the foil as it corroded.

Experiment B: The nail covered in dry salt has also corroded badly - even though we dried off all the water (water is present in all our other examples of corrosion). The nail without salt on it is still shiny and uncorroded. If the experiment is left for a longer period, you may notice a very small amount of corrosion on the nail without salt, but the salty nail is much more corroded.

Experiment C: Perhaps the most amazing result is the painted nails. The nail that had corroded in fresh water has been fully protected from further corrosion by the paint, but the nail that corroded in the salt water has corroded - even though we wiped off all the salt and there was no water under the paint coating.