In the equation, #2Al + 2Fe^(3+) + 3O^(2-) -> 2Fe + 2Al^(3+) + 3O^(2-)#m which element has been reduced?

1 Answer
Jan 25, 2016

#Fe^(3+) + 3e^(-) rarr Fe#

Ferric ion has been REDUCED.


Reduction involves a formal GAIN of electrons. Oxidation involves a loss of electrons. In the reaction above, clearly ferric ion, #Fe^(3+)#, has been REDUCED.

The correct reaction is:

#Al + Fe^(3+) rarr Fe + Al^(3+)#

This occurs because aluminum is a more active metal than iron. Note that in this respect, the aluminum acts as a sacrificial anode, which is a very important strategy for the prevention of corrosion. Corrosion of structural steel is thermodynamically downhill; of course here, corrosion occurs to the aluminum and not the structural steel.