OXIDATION-REDUCTION REACTION

TB 43-0213

OXIDATION-REDUCTION REACTION

The corrosion process called "rusting"

It begins with water on a metal surface

It begins with moisture on metal. This moisture

polarizes the iron atoms in the metal. Purer

portions of the iron become positive areas. Those

parts of the metal containing more impurities

become negative areas.

The positive charged iron atoms begin to attract

electrons from the weaker negatively charged iron

atoms. These electrons are pulled from the

negative iron atoms and migrate toward the positive

areas.

At the same time, the weakened iron atoms in

negative areas of the metal migrate toward the

surface of the metal where they begin to dissolve

into the moisture on the surface.

The electrons pulled into the positive areas of the

metal now come into contact with the oxygen

atoms found in the moisture on the metal surface.

These oxygen atoms seize upon the electrons. In

turn, the electron charged oxygen atoms now

merge with the weakened iron atoms dissolving on

the surface. This merging forms a new molecule -

the molecule of iron-hydroxide, a crusty, flaky

form of metal commonly known as rust.

TA504742

Figure 2-1. Oxidation-Reduction Reaction.

2-2