Half reactions:E

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Half reactions ECell 1.5 V Anode Zn(s) g
Zn2(aq) 2e- Cathode 2NH4(aq) MnO2(s)
2e- g Mn2O3(s) 2NH3(aq) H2O(l)
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Anode (oxidation) Zn(s) 2OH- (aq) g ZnO(s)
H2O (l) 2e- Cathode (reduction). 2MnO2 (s)
2H2O (l) 2e- g Mn(OH)2(s)
2OH-(aq) Overall Cell reaction 2MnO2 (s) H2O
(l) Zn(s) g ZnO(s) Mn(OH)2(s) Ecell
1.5 V
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Half reactions ECell 1.6 V Anode Zn(s)
2OH-(aq) g ZnO(s) H2O(l) 2e- Cathode
(Ag) Ag2O (s) H2O(l) 2e- g 2Ag(s)
2OH-(aq)
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• 2H2(g) O2(g) ? 2H2O(l)
• anode 2H2 4OH? ? 4H2O 4e?
• cathode 4e? O2 2H2O ? 4OH?

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Fuel Cells
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• Pb PbO2 2H2SO4 2PbSO4 2H2O

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Half reactions ECell 2.0 V Anode Pb(s)
SO42- ? PbSO4 (s) 2 e- E 0.356 Cathode
(Hg) PbO2 (s) SO42- 4H 2e- ? PbSO4
(s) 2 H2O E 1.685V Net PbO2 (s) Pb(s)
2H2SO4 ? PbSO4 (s) 2 H2O ECell 2.0 V
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Tin Can
Aluminum Cans
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