Iron is Fe and Fe2O3 is red rust.O2 is oxygen. Youmight think that water is required for this process but it is not, itmerelyspeeds it up. Notice that the iron is nowbound to the oxygen.It has gone from its elemental state with no charge ( Fe0)toits ionic state (Fe3+) Becausethe iron has lost electrons and become positively charged, it has beenoxidized. The oxygen has been reduced.The electrons from the iron went to the oxygen.Every oxidation process has to have a corresponding reduction.We call these redox reactions, the word redox combining reductionand oxidation.
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We can write half reactions for this totalreaction:
Oxidation 4 Fe -> 4 Fe3+ + 12 e-
Reduction 3 O2 + 12 e–> 6 O2-
Some metals are more stable in their elemental state than others.Gold, Platinum and silver are hard to oxidize.Other metals such as lithium magnesium and alluminum are easy tooxidize.When they oxidize they change into their ionic state.If you put Zn metal into a solution of Cu2+ and SO42-an interesting thing happens. Thezinc goes into solution and the copper begins to plate out as solidcopper (Cu0).The equation for this is
The zinc and the copper are solids and the ions are in solution.Notice that the sulfate (SO42-) is notchangingduring the reaction. We call theseions spectator ions. Why does thisreaction occur? Copper is morestable than zinc. Copper is belowzinc on the activity series.
The activity series.
The redox half-reactionsfor the abovereaction would be:
Oxidation: Zn(s)->Zn2+(aq) + 2e-
Reduction: Cu2+(aq)+ 2e- ->Cu(s)
The oxidation of a Zinc atom releases 2 electrons
The reduction of a Copper ion is achieved by the acceptance of 2electrons
Thus, there would appear to be amovement, orflow, of electrons from the Zinc metal to the Copper ions
We can capture the power energy produced in this reaction in abattery.The battery can use this flow of electrons to do work.Please read about voltaic cells at
The lead-acid storage battery uses lead 0 (elemental) and lead 4+.
Oxidation: Pb(s) ->Pb2+(aq) + 2e-
The lead gives away two electronsthrough thewire and becomes Pb2+which combines with SO42-to become lead(II)sulfate.
Reduction: Pb4+(s)+ 2e- ->Pb2+(aq)
The leadhere starts asPb4+ as it combines with 2 O2-. Itcan take the two electrons from the wire and become Pb2+whichcombines with SO42- to become lead(II)sulfate.
Again, asthe electronspass through the wire they create a voltage which can be used to dowork.