Construction and Operation of an Electrolytic Cell
Letís use the tin-copper voltaic cell shown in Fig 21.17A:
The spontaneous reaction of Sn metal through oxidation to form Sn2+ions
and the reduction of Cu2+ ions to form copper metal will produce a cell
voltage of 0.48 volt. Therefore, the reverse reaction is nonspontaneous
and never happens on its own. We can make the reverse reaction occur
by supplying power from an external source with an electric potential
greater than Eocell. We convert the voltaic cell into an electrolytic cell
and reverse the electrodes.
Sn(s) Sn2+(aq) + 2 e- [anode; oxidation]
Cu2+(aq) + 2 e- Cu(s) [cathode; reduction]
Sn(s) + Cu2+(aq) Sn2+(aq) + Cu(s) Eocell = 0.48 V and Go = -93 kJ
Cu(s) Cu2+(aq) + 2e- [anode; oxidation]
Sn2+(aq) + 2 e- Sn(s) [cathode; reduction]
Sn2+(aq) + Cu(s) Cu2+(aq) + Sn(s) Eocell = -0.48 V and Go = 93 kJ
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