Iron Rust Science Project Idea

What Causes Iron to Rust?

This question may be answered by performing the following experiment.

Iron Rust Science Project Experiment I

Put into a test tube a small quantity of iron filings and a few drops of water. Move the test tube around until the moist iron filings form a layer sticking to the inside of the tube. Place the test tube, mouth down, in a glass of water. Note how much of the tube is filled with air. Examine again on the following day.

Iron Rust Science Project Experiment II

Test the air that remains in the test tube for the presence of oxygen. This may be done as follows: Keeping a finger over the bottom of the test tube turn it so that the mouth is up. Insert into the air in the test tube a lighted splinter or taper. Does the taper continue to burn? What does this prove? What, therefore, do you think happens in the rusting of iron ?

Can you suggest a reason for not noticing any heat or light?

It is evident that some cases of oxidation are relatively slow. It is interesting to note that moisture also is necessary for the rusting, so that this process of oxidation is not quite so simple as some of the other cases which have been mentioned.

In addition to the rusting of iron there are many other common happenings which are the result of slow oxidation.

Rub a match over the hand in the dark. What do you observe? If paint containing linseed oil is allowed to stand a short time, a tough skin is formed on its surface. This is caused by slow oxidation of the oil in the paint. The same thing happens when the paint is spread upon a surface. The "drying" of such paint is due to oxidation, and not to real drying.

Oily rags which have been thrown together in a heap sometimes catch fire. What is the explanation of this fact?

The oil slowly oxidizes and the heat which is produced gradually increases until the temperature has been raised to the kindling point. The whole mass will then break into flames. This is called spontaneous combustion. Why does oily clothing not catch fire spontaneously if hanging?

It is not an uncommon occurrence in the country for a barn filled with slightly damp hay to catch fire. In this case the production of heat is probably hastened by the action of small living plants, called bacteria, which are present on the stems of the grass or come from the air. The hay does not give off the heat readily, and finally, as in the case of the oily rags, sufficient heat accumulates until the kindling point is reached.

The heat produced in a hotbed is formed in the same way as the heat was produced in the hay barn, but it does not reach the point where the oxidation becomes rapid enough to give off light. A hotbed is made of decomposing organic matter, usually a mixture of straw and horse manure. This is covered with a layer of soil. The bed is enclosed with frames of glass or cheesecloth to prevent the escape of the heat produced. The hotbed is used for forcing the early growth of plants.

Explosions occur in poorly ventilated coal bunkers and flour warehouses. How can you account for this? Why is the fineness of the dust particles a factor? Why is an explosion not apt to occur unless the ventilation is poor?