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Chemistry: Rusting
Oxidation is a type of combination reaction called in which one substance combines with oxygen. Rusting is a specific type of oxidation in which iron combines with oxygen. The chemical name for rust is iron oxide (iron III oxide). This oxide has a reddish brown color as shown in collage of pictures above.
In order for iron to rust these conditions are necessary:
1. oxygen must be present and in contact with the metal
2. the metal has to donate electrons and the oxygen accept them
3. there has to be a way, such as the presence of water, for the electron exchange to take place between the metal and oxygen
FACTS:
Conductors are materials that encourage the transfer of electrons.
Non-conductors are materials that interfer with the transfer of electrons.
Aqueous solution is a mixture of water and anything that will dissolve in it. Aqueous solution are conductors. This is why iron materials left out in the rain are more likely to rust than those that are kept dry.
Painted metal does not rust because the metal is not in contact with oxygen. Scratches in the paint that expose the metal result in the exposed metal rusting.
For information about writing and balancing the chemical equation for the oxidation of iron, see CHEMISTRY: RUSTING EQUATION
