Corrosion of metals
Chemijos laboratorinis darbas. The aim and objectives. Corrosion of tin plated iron and zinc plated iron. Corrosion of iron nails in various solutions.
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 process in which an atom (or ion) loses electrons is called oxidation. This process results in an algebraic increase of its oxidation number. The process in which an atom (or ion) gains electrons is called reduction. This process results in an algebraic decrease of its oxidation number.
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.