write acidic theory and electro chemical theory of corrosion?
Electrochemical theory: Corrosion can be defined as the deterioration of materials by chemical processes. Of these, the most important by far is electrochemical corrosion of metals, in which the oxidation process M --> M+ + e– is facilitated by the presence of a suitable electron acceptor, sometimes referred to in corrosion science as a depolarizer.
Acidic theory: Corrosion is the primary means by which metals deteriorate. Most metals corrode being in contact with water (and moisture in the air), acids, bases, salts, oils, aggressive metal polishes, and other solid and liquid chemicals. Metals will also corrode when exposed to gaseous materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing gases. Corrosion specifically refers to any process involving the deterioration or degradation of metal components. The best known case is that of the rusting of steel. Corrosion processes are usually electrochemical in nature, having the essential features of a battery.