1. Voltaic Cells Batteries, etc.

2. Essentials Electrochemical setups that can generate electricity They release energy and are spontaneous E cell is positive (by definition) Viewed as sources of energy Voltage depends on the chemical reaction Amount (amps) depends on the size of the cell

3. Many types of batteries Dry Cells ("D", "AA" "AAA" ) Lithium ion battery Car Batteries (Lead Acid) Rechargable (can be some types of lithium or Nickel/ Cadmium (Ni/Cad) Fuel Cells (Hydrogen/Oxygen)

4. The Chemical Reaction Overall 2MnO 2 + Zn  Zn 2+ O + Mn 2 O 3 The zinc is oxidized: Zn0  Zn 2+ + 2 e - The manganese is reduced: 2 x [1 e - + (Mn 4+ )O 2 ]  (Mn 3+ ) 2 O 3

5. The Lead Acid Battery Used in automobiles Made of Lead plate, lead oxide and sulfuric acid nasty and toxic Great for holding a LOT of electricity Good for rapid charge and discharge Lots of rapidly available power (as in turning around a 300 pound car engine fast enough to get it started) Made of 6 cells put together: each cell gives 2 volts, Together they make 12 volts.

6. The chemical reaction: The discharge… PbO 2 + 2 H 2 SO 4 + Pb  2PbSO 4 + H 2 O Some lead is oxidized: Pb0  Pb 4+ + 2 e – (SO 4 2- is a spectator) Some lead is reduced: 2 e - + Pb 4+ O2  Pb 4+ + H 2 O (SO 4 2- is a spectator) 2 e -