Corrosion Of Metals

Corrosion of metals.

The aim and objectives: To test out the corrosion of iron according to the solutions pH. Test the effectiveness of plating iron in other metals to prevent the corrosion. Familiarize in writing oxidation and reduction half-reactions.

The oxidation – reduction reaction is one in which atoms of at least two elements undergo changes in oxidation state (number).

Adding these two halfreactions and noting that iron(II) hydroxide is insoluble we obtain for the primary corrosion reaction:

In order to protect iron from corrosion iron can be plated in a thin layer of second metals. By plating in more reactive metals like zinc iron is protected from corrosion. Zinc is more active than iron. The oxidation occurs in the zinc plating the iron being still protected. So, in this case not iron but zinc is oxidized.

In the anodic reaction (oxidation) the iron loses electrons to produce iron ions. Cathodic reaction (reduction) depends on pH of the solution. In acidic solutions the reaction of hydrogen ion reduction takes place, while in neutral and alkaline solutions the dissolved oxygen reduces.