Electrochemistry. The study of the exchange of chemical and electrical energy. Oxidation-Reduction reactions take place in electrochemical cells. Each electrochemical cell consists of two solid conductors called electrodes. Two types of electrochemical cells: Voltaic Cell Electrolytic Cell.
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Cu+2(aq) + Zn (s) -------> Cu (s) + Zn+2(aq)
Zn (s) ----------> Zn+2(aq) + 2e-
As zinc is oxidized, the zinc electrode will slowly dissolve to produce zinc ions, which enter into the solution.
Cu+2(aq) + 2e- -------> Cu (s)
As copper is reduced, copper atoms accumulate on the surface of the solid copper electrode.
The reaction will not occur.There is no way for the electrons lost by Zinc to get over to the Copper ions and reduce them to Copper metal.
Now that the electrons have a path to the Cu/Cu2+ side it would appear that the reaction can proceed,
but it does not.
We need a way to neutralize the charge build-up in the solutions due to the change in ion concentration
What if we had a tube filled with aqueous solution that connected the two redox reactions?
This tube contains
an electrolyte and is called a salt bridge.
Electrode Process Eo/V
Li+(aq) + e- Li(s) -3.03
K+(aq) + e- K(s) -2.92
Zn2+(aq) + 2e- Zn(s) -0.76
Cu2+(aq) + 2e- Cu(s) +0.34
Electrons flow from the anode to the cathode where cations undergo reduction.