Question
What is corrosion? What are the factors which effect corrosions? CO2 is always present in natural water. Explain its affect (increases, stops or no effect > on rusting of Fe.)
Solution
Corrosion slowly coats the surfaces of metallic objects with oxides or other salts of the metal. The rusting of iron, tarnishing of silver, development of green coating on copper and bronze are some of the
examples of corrosion.
Carbon dioxide reacts with water:
CO2 + H2O --> HCO3- + H+
As the concentration of CO2 increases, so does the concentration of the H+ ion. This ion then react with Fe in metals: Fe + 2H+ --> 2H (atom) + Fe2+ As corrosion proceeds, the ferrous ions produced react with the bicarbonate ions to form ferrous carbonate which precipitated as a scale
