4. Lab Experiment to Demonstrate Importance of Oxygen in the Corrosion of Iron


Objective To demonstrate the importance of oxygen in the corrosion of Iron in 3.5% NaCl solution.
Materials One cylinder of Oxygen and Nitrogen each, with pressure gauges and control valves
Two 500 ml, Pyrex conical flasks
Two 10 inch length of 6-8 mm, glass tubing
Suitable lengths of rubber tubing
3.5% Na Cl solution
Two steel wool



Pour 250 ml of 3.5% NaCl solution in to each of the 500 ml conical flasks. Use gleass tube as bubblers. Connect one to the source of nitrogen and allow it to bubble through 3.5% NaCl solution in one of the flasks. Similarly allow oxygen to bubble through 3.5% NaCl solution in the second flask. Introduce the steel wool in to both the flasks containing 3.5% NaCl solution.



Continue bubbling the gasses through their respective flasks and observe the developments of rust during a period of several hours.




After a couple of hours,



Iron does not corrode in water saturated with nitrogen. Oxygen is a corrodant as shown by the change of color of water to brown because of corrosion of iron. Passing nitrogen in the system to blanket oxygen is called Deaeration.

VIDEO: Click below to see this experiment in action: 

             Corrosion in presence of oxygen - 1
Corrosion in presence of oxygen - 2
Corrosion in presence of oxygen - 3