Today’s Wonder of the Day was inspired by aundrea. aundrea Wonders, “I wonder why metal rusts?” Thanks for WONDERing with us, aundrea!
Have you ever seen a very old car? How about an old metal key or set of tools? Maybe you’ve seen an old bicycle lying around. If any of these things have been abandoned and uncared for over several years, they’re probably in bad shape. In fact, they’ve probably turned a reddish-brown color. They might even be flaking in many places.
What is that reddish-brown material? These are spots where the metal has corroded, and they’re called rust. When metal objects become rusted, they’re in danger of ruin. Unless they’re properly cared for soon, they won’t be of any use to anyone.
But did you know rust isn’t always that reddish-brown color? Would you believe that sometimes, it’s green? It’s true! When iron reacts with chloride in an underwater environment, green rust appears. This can sometimes be seen on steel used in underwater pillars.
Rust occurs when iron or its alloys, such as steel, corrode. The surface of a piece of iron will corrode first in the presence of oxygen and water. Given enough time, any piece of iron will change entirely into rust and disintegrate.
The process of rusting is a combustion reaction, similar to fire. Left in contact with oxygen, iron will react with the oxygen to form rust. Unlike fire, though, the reaction is much slower and does not create a flame.
There are certain factors that can speed up the rusting process. For example, water speeds up the reaction. Other substances, such as salt, can also increase the speed of the rusting process.
To prevent rust, iron can be coated. This prevents its reaction with oxygen and water. One such process is called galvanization. This usually involves coating an iron object with a layer of zinc. The zinc helps to stop the iron from reacting with oxygen and water to form rust.
Another method of preventing rust is much simpler and common. What is it? Paint! That’s right. A simple coat of paint can prevent iron from reacting with oxygen and water in the environment.
Do you have any rusty items around your house? How can you help protect them from corrosion? Act fast! They could be beyond repair before you know it.
Standards: CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, NGSS.PS1.B,