Chemistry of Batteries
Mercury and Silver (Button) Batteries
Anode (oxidation):
Zn(s) + 2 OH-(aq) ZnO(s) + H2O(l)
Cathode (reduction) (mercury):
HgO(s) + H2O(l) + 2 e- Hg(l) + 2 OH-(aq)
Cathode (reduction) (silver):
Ag2O(s) + H2O(l) + 2 e- 2 Ag(s) + 2 OH-(aq)
Overall (cell) reaction (mercury):
Zn(s) + HgO(s) ZnO(s) + Hg(l); Ecell = 1.3 V
Overall (cell) reaction (silver):
Zn(s) + Ag2O(s) ZnO(s) + 2 Ag(s); Ecell = 1.6 V
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