The Nail Rusting Experiment

This nail rusting experiment investigates the effect of salt concentration on the speed at which iron corrodes. The materials for this project are usually available in the home or shed. This experiment lays a good foundation for your child for understanding complex concepts such as electron transfer and chemical reactions in general in future years.

Materials Needed:

* 4 see through drinking glasses or plastic cups

* 4 iron nails, preferably large ones

* table salt

* tap water

* a jug

* a waterproof marker

Procedure:Fill the jug with water from the tap. Make the strongest salt solution you can at room temperature by stirring salt vigorously into the jug until no more will dissolve. At this point you will see any extra salt that you add simply settling to the bottom of the jug and not disappearing into the water.

Line up 4 glasses and label them "none", "1/4", "1/2" and "all" with the waterproof marker. Now place that amount of salt solution in the appropriately labeled glass, as shown by the red liquid in the picture below:

What Will Happen?

You have made a series of increasingly concentrated salt solutions. The salt in the water will speed up the rusting of the iron nail as salt water is a good conductor of electricity. In water, the reaction occurring at the surface of the metal is an oxidation reduction reaction also called a redox reaction. The presence of extra salt in the water caused the electron transfer to occur more rapidly.

This experiment lets your child discover the effect of salt on metal and lays the foundation for understanding electron transfer in metals as they corrode, and in reactions in general.

Extension Activities:

For the curious child, testing different types of nails in the salt solutions is a logical next step. This will work best with nails (or screws or bolts) of different metals such as copper, brass, and other pure metals or alloys.

If your child wants to explore the behavior of other metals in this nail rusting experiment, it is best to encourage her to write down dates of observations and make drawings of the various states of the metals being tested.

Another possibility is to test several metals at once to see which rusts the quickest. For this you will need to prepare cups of same strength salt solution or the comparison between the metals will be unbalanced.