What is Fe_3O_4Fe3O4, and how do we represent its formation from iron, and water?

1 Answer
Aug 28, 2017

This is a mixed valence oxide of FeOFeO and Fe_2O_3Fe2O3........

Explanation:

In the original redox reaction, elemental iron is OXIDIZED to FeO + Fe_2O_3FeO+Fe2O3, i.e. FeO*Fe_2O_3-=Fe_3O_4FeOFe2O3Fe3O4.

And so we write 2 separate oxidation rxns....

Fe +H_2O rarr FeO+2e^(-) +2H^+Fe+H2OFeO+2e+2H+, and....

2Fe +3H_2O rarr Fe_2O_3+6H^(+) + 6e^(-)2Fe+3H2OFe2O3+6H++6e

We adds these together and get.....

3Fe +4H_2O rarr underbrace(Fe_2O_3+FeO)_(Fe_3O_4) +8H^(+) + 8e^(-) (i)

And for every oxidation, electron loss, there is a corresponding reduction, electron gain, and the most likely oxidant is dioxygen gas.....

1/2O_2 + 2H^+ + 2e^(-)rarrH_2O (ii)

And so we take 4xx(ii)+(i) to eliminate the electrons from our final redox equation.......

3Fe +2O_2 + cancel(4H_2O +8H^(+) + 8e^(-)) rarr underbrace(Fe_2O_3+FeO)_(Fe_3O_4) +cancel(8H^(+) + 8e^(-)+4H_2O)

To give finally.......

3Fe +2O_2 rarr underbrace(Fe_2O_3+FeO)_(Fe_3O_4)

Fe_3O_4 is a mixed valence iron oxide.....Fe_2O_3*FeO