Corrosion- Investigating rusting

Aim:
To investigate the factors that cause rusting in iron.

Equipment:
Six test tubes
Test tube rack
Bung
Six iron nails
Boiled water
Tap water
Salty water
Cooking oil
Calcium Chloride


Method:
1. Label four test tubes A-D and place in a test tube rack.
2. A= Iron nail and tap water
    B= Iron nail with salty water
    C= Iron nails, boiled water, oil
    D = Iron nail and calcium chloride, sealed with a bung
    E= Nail polish + water
    F= Mg wrapped around the nail + water
3. Leave the test tubes undisturbed for three days.

Results:  

           

Discussion:

When Metals are exposed to the environment, they can deteriorate, or break down. This is called corrosion. Rust is used to describe the corrosion of Iron. Rusting of Iron requires water and Oxygen, if either of these elements is removed, corrosion will not occur. The process of rusting will be much quicker if Salt is present. The easiest way to prevent rusting is by preventing the iron from being exposed to Oxygen or water. By coating/painting the iron nail in paint or grease, a barrier is created, preventing the environment corroding the Iron. Corrosion can also be prevented by coating the Iron in another more reactive metal such as Zinc or Magnesium. Our class used Magnesium. 

Nail results

A- Iron nail and tap water

-  This nail came out rusty. As there is nothing preventing the exposure to water, the nail is going to get to the nail and cause corrosion.  

B- Iron nail and salty water

- This nail was slightly rusty. As Iron corrodes in the presence of Oxygen and water, the nail is rusting as the water contains dissolved Oxygen. It is also rusting faster than it would if there was no salt in the water. 

C- Iron nail, boiled water and Oil. 

- This nail had no rust. The oil in the test tube creates a barrier between the nail and Oxygen. As there is no exposure to the Oxygen, there is nothing for the water to react to, so corrosion will not occur. 

D- Iron nail, Calcium Chloride, sealed with a bung. 

- This nail had no rust. The Calcium chloride dried out the air and the bung prevented any other oxygen from entering the test tube. 

E - Iron nail, Nail polish and water. 

- This nail had slight rust. Mr Heath explained that this was probably because we did not paint thick enough of a layer of Nail polish onto the nail. The nail polish should have created a barrier between the nail and the water, but as we did not paint a thick enough layer, it rusted. 

F- Mg wrapped around the nail and water. 

- There was no rusting on the nail itself, but the Magnesium itself had corroded. Zinc is also used to prevent corrosion in Iron nails. When an Iron nail is coated in Zinc, it is called a Galvanised nail. The Zinc layer stops the Oxygen/Water from attacking the Iron. While Zinc is more reactive than iron, it offers physical protection but also provides chemical protection. 

Conclusion:

Rusting of Iron requires Oxygen and water. For example, when Iron is exposed to moist air, it reacts with Oxygen to create rust. Many of these methods used in this experiment prevented the rust very slightly. If you are looking for nails that do not corrode, I recommend Galvanised nails.