How do we represent the formation of #Fe_3O_4# by the oxidation of iron metal in basic conditions?

1 Answer
anor277
Jul 11, 2017

#3Fe(s) +8H_2Orarr Fe^(2+) + 2Fe^(3+)+4H_2(g) +8HO^-#

Explanation:

If you got #Fe_3O_4#, this is mixed valence oxide of iron ......it occurs as the mineral magnetite, which we could formulate as #FeO*Fe_2O_3-=Fe_3O_4#.......

And so metallic iron is oxidized to #Fe^(2+) + 2xxFe^(3+)#............

#3Fe(s) rarr Fe^(2+) + 2Fe^(3+)+8e^(-)# #(i)#

But something must be correspondingly reduced.....and here it is the protium ion in water........

#H_2O+e^(-) rarr1/2H_2(g) + HO^-# #(ii)#

And so I take #(i)+8xx(ii)# to gives...........

#3Fe(s) +8H_2Orarr Fe^(2+) + 2Fe^(3+)+4H_2(g) +8HO^-#

Charge and mass are balanced as is required...........

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