Saturday, August 15, 2015

What causes rusting?

When iron or steel is left in the wet for some days it begins to rust. But what really causes rusting? Let’s perform an experiment like scientists do and find out for ourselves. (Level: Kids 8 to 10)

Buy some new nails from the nearby hardware store. Find three glass jars which can be corked tight. Drop some nails into each of them and pour some water into the first jar. Put a little lime in the second, and boiled water in the third, filling it to the brim. 

All the air dissolved in water is driven out when it is boiled for sometime. Now cork up the three jars. After a few days you’ll be surprised to see that the nails in the first jar have turned reddish brown, but those in the other two haven’t rusted at all.

You wonder why. Well, iron rusts only when both air and water are present. In the second jar there was air but no water and the third had only water.

Now how do you prevent iron or steel from rusting. By stopping air and water from reaching it’s surface. This is done by coating them with special paint.