How do acids and bases corrode iron

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Corrosion is commonly understood to mean the oxidation of metals due to environmental influences. The course of corrosion depends on the one hand on the properties of the metals in question and on the other hand on the type of medium with which the metal is in contact. Moisture plays an important role in corrosion. Corrosion processes are diverse and often complex.

The simplest case of corrosion is the reaction of the metal surface with aggressive substances from the environment, i.e. the reaction of base metals with air pollutants such as sulfur dioxide, which reacts with humidity to form sulphurous acid and as a result of oxidation by atmospheric oxygen to form sulfuric acid. Other air pollutants such as chlorine or acid vapors, which react directly with many metals, can also occur in industrial production plants or laboratories. These conversions should be regarded as ordinary redox reactions.

More complicated redox processes occur when metals are destroyed by the formation of electrochemical elements or by electrolysis processes.

It is well known that iron and simple steels rust in moist air without the need for other reactants. A direct reduction of oxonium ions in water by iron should not play a special role because at = 7 their concentration is very low. In the neutral and alkaline area, oxygen corrosion occurs preferentially. The electrons given off by the metal

are absorbed by the oxygen