#Fe->Fe^(3+) + 3e^-# steel is oxidised: it"s shedding electrons#O_2+4e^(-) ->2 O^(2-)# oxygen is reduced, it"s getting electrons

Balance for the electrons. The smallest usual product that 3 and also 4 is 12.So we get:#4Fe->4Fe^(3+) + 12e^-##3O_2+12e^(-) ->6 O^(2-)#

Adding:#4Fe+3O_2+12e^(-)->4Fe^(3+) + 12e^(-) + 6O^(2-)#

The electron balance for this reason they cancel out:#4Fe+3O_2->4Fe^(3+) + 6O^(2-)#

Since #Fe# and also #O# can integrate in a ratio of 2:3#4Fe+3O_2->4Fe^(3+) + 6O^(2-)->2Fe_2O_3#

Extra :Pure stole won"t rust, due to the fact that the oxide great would form a safety skin (as aluminium does). It demands some impurities (mainly carbon) and, apart from the oxygen, part moisture -- also carbondioxide "helps". In that case iron-hydroxy-oxides and also -carbonates are formed, and also these flake, no much longer protecting the steel underneath.

You are watching: What happens to iron when iron oxide becomes elemental iron?


Answer link
*
*

Michael · Media Owl
january 13, 2015

Meneer has written wonderful answer so ns will add some information which he has actually referred come in his extra paragraph.

Rusting is fastest when iron and steel is exposed to a combination of air and water and is also impacted by impurities in the iron and the presence of other electrolytes.

Rusting is one electrochemical process. Cells are collection up in the steel surface wherein different areas act together sites that oxidation and reduction.

See more: Distance From Bar Harbor To Portland Maine ) From Bar Harbor

The two fifty percent - cell are:

#Fe_((aq))^(2+)+2erarrFe_((s)) E^(0)=-1.44V#

#(1)/(2)O_(2(g))+H_2O_((l))+2erarr2OH_((aq))^(-) E^(0)=+0.40V#

The most positive half - cabinet is the one which will certainly take in electron so you can see the #O_2#/#H_2O# will oxidise #Fe# come #Fe^(2+)#.

The diagram reflects what happens as soon as a autumn of water is left in contact with steel or steel:

*

At the edge of the drop whereby the concentration of liquified oxygen is higher, oxygen is reduced to hydroxide ions:

#O_(2(g))+2H_2O_((l))+4erarr4OH_((aq))^-#

The electrons necessary to execute this circulation in from the oxidation of iron at the centre of the drop. (Known as "pitting"). Here the #Fe^(2+)# ion pass right into solution:

#2Fe_((s))rarr2Fe_((aq))^(2+)+4e#

As the #Fe^(2+)# and #OH^-# ions diffuse away from the surface ar they do not form a safety layer however a precipitate of iron(II) hydroxide i beg your pardon "flakes" away. This is climate oxidised additional by oxygen: