Electrochemical Cells

Spontaneous Redox Reaction - Zn + Cu2+

Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)

Non-Spontaneous Redox Reaction - Water

2 H2O(l) 2 H2(g) + O2(g)

Battery Construction - Zn + Cu2+

Zn|Zn2+||Cu2+|Cu

Volta’s Pile

Commercial Cells - Le Clanche (Dry) Cell

Zn | Zn2+, NH4Cl, MnO2 | C

Zn + 2 MnO2 + 2 NH4+ Mn2O3 + 2 NH3 + H2O + Zn2+

Commercial Cells - Lead Storage Battery

Pb(s) | PbSO4(s) | H2SO4(aq) | PbSO4(s) | PbO2(s) | Pb(s)

Pb + PbO2 + 2 H2SO4 2 PbSO4 + 2 H2O

Commercial Cells - Nickel-Cadmium Battery

Zn | ZnO2 | OH- | Hg | HgO

Zn + HgO ZnO + Hg

Battery Connections

Series Connection

Parallel Connection

Historical Origin of Sign Convention

Cell Conventions

Standard Hydrogen Electrode (SHE)

SHE || Cathode

Pt(s) | H2(g,f=1) | H+(aq,a=1) || Cathode