|MadSci Network: Chemistry|
Thank you for asking your question about chemistry. Iron forms compounds in which it has a valence of +2 (formerly ferrous compounds) and compounds in which it has a valence of +3 (formerly ferric compounds). Iron(II) compounds are easily oxidized to iron(III) compounds. On the surface of the Iron(II) solution (and to a limited extent within it), the Iron (II) comes into contact with oxygen in the air. This oxygen will grab an electron from the Iron (II), oxidising it to Iron (III). In this REDOX reaction the oxygen will be reduced to the oxide ion which has a charge of -2. The oxygen combines with the Iron (II) to form Iron (III) oxide which will be seen as a rusty red solid. I hope this answers your question. Sean Hunt
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