Electrochemistry

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Electrochemistry Lesson 8 Electrochemical Cells
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Electrochemical cells are Batteries
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Alkaline Batteries
KOH
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Car Batteries
Pb-Acid H2SO4
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Mitsubishi iMiEV - Pure Electric Car
36,000 US
50,000 Can
Powered by a 330 v Li-Ion Rechargeable battery
Plugs into your house and takes 14 hours to
charge -100 km for 0.60
Top Speed 130 km/h 63 hp and 133 lb.-ft. of
torque
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Cell Phone batteries
Lithium Ion Rechargeable battery
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Lithium Coin Cell
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Space Ship Batteries
Powered by Radioisotopes
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Ni-Metal Hydride
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Notes on Electrochemical Cells  
An electrochemical cell a system of electrodes,
electrolytes, and salt bridge that allow
oxidation and reduction reactions to occur and
electrons to flow through an external circuit.
The salt bridge allows ions to migrate from
one half-cell to the other without allowing the
solutions to mix.
1. Spontaneous redox reaction       2. Produces
electricity from chemicals 3. Is commonly called
a battery
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Analyzing Electrochemical Cells The reaction
that is higher on the reduction chart is the
reduction and the lower is oxidation and is
written in reverse.
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For any cell  Oxidation always occurs at the
anode and reduction at the cathode Electrons flow
through the wire and go from anode to
cathode Anions (- ions) migrate to the anode and
cations (ions) migrate towards the cathode
usually through the salt bridge
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1. Draw and completely analyze a Cu/Sn
electrochemical cell.
voltmeter
e-
e-

Higher Greatest Electron Affinity Reduction Cathod
e Cu2 2e- ? Cu(s) 0.34 v Gains mass
0.48 v
Lower Oxidation Anode Sn(s) ? Sn2
2e- 0.14 v Loses mass -
Na-
Sn
NO3-
Cu
Cu2
Sn2
NO3-
NO3-
Overall Reaction Cu2 Sn ? Sn2
Cu(s) 0.48 v
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The Hydrogen half cell involves a gas and
requires an inert or nonreactive Pt electrode.
Wire to circuit
H2(g) in

H Cl-
Pt(s)
1 M HCl
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Draw a H2/Ag electrochemical cell with a KNO3
salt bridge.
voltmeter
2e-

2e-
0.80 v
1.0 M KNO3
Higher Greater electron affinity Reduction Cathode
Ag 1e- ? Ag(s) 0.80 v Gains mass
Ag
H2
NO3- K

oxidation Anode - H2 ? 2H 2e- 0.00 v pH
decreases
Ag NO3-
H Cl-
1 M HCl
1 M AgNO3
2Ag H2 ? 2Ag 2H 0.80 v