Why Does Copper Oxidize?

why-does-copper-oxidizeCopper is an industrial metal that has been in use since ancient times. It is a malleable metallic element, which serves various uses. It can be made into thin sheets and can be used to make thin wires since it is quite ductile. It is also a necessary element found in our bodies. And like other elements, it also oxidizes like iron and aluminum.

Understanding Oxidation

Oxidation is a phenomenon that occurs in everyday life. You would notice that a freshly cut apple would turn brown when it is exposed to the air. When oxidation occurs that element will eventually lose electrons while interacting with another element. Another example of this that we regularly see in daily life is the formation of rust on iron.

Effects of Oxidation

When exposed to air, iron forms a flaky reddish outer layer, which we call rust. Rust is the result of this natural process and leads to corrosion. Like the formation of rust on iron, copper will also oxidize as it reacts with oxygen. What forms is copper oxide, which is greenish in color. This green layer forming on top when it oxidizes is known as patina. However, unlike iron, this element does not react with water when exposed to it. Iron on the other hand is sure to form rust when exposed to water.

Another big difference and diametric opposite is that where rust corrodes patina protects. This is also yet another reason why copper is such a valued metal since it is corrosion resistant. Underneath the oxidized layer, patina averts any further corrosion. This is also used as a waterproofing layer on the roofs of old buildings.

An example of oxidation is the one that you will see on the Statue of Liberty. The copper in it has a green colored protective layer, which is only about 0.005 inch thick. This protective layer of patina protects Lady Liberty from being exposed to air and water. Oxygen and water is prevented from reacting through this layer of patina.

Heat Transfer

Heat can still be transferred even if patina forms after this element has oxidized. The idea for this process is pretty much the same as with a convection oven. Oxidized copper is still pretty malleable in spite of the layer of patina on the surface. Since that layer is very thin, it has no effect on this element’s ability to radiate heat. However, take note that you may still see some varying results depending on what method you use to transfer heat.

Related Posts