2. Batteries

3. Electrochemical cells  Terms to know Anode Cathode Oxidation Reduction Salt Bridge Half cell Cell potential Electron flow Voltage

4. Batteries  A battery is what you call an electrochemical cell  It consists of 2 half cells or half reactions One half cell produces electrons One half cell receives electrons The flow of electrons is electricity!!!

5. Half Cells or half reactions  Anode Electrons are produced here By removing electrons from metal, positive ions are produced in solution ○ The anode becomes smaller Oxidation is when electrons are lost. ○ OIL: Oxidation is lost

6. Half Cells or half reactions  Cathode Electrons are received here Cations in solution receive electrons and become metals ○ The cathode grows in size Reduction is when electrons are gained. ○ RIG: Reduction is gain

7. Electricity is just electrons moving  The electrons move from the anode to the cathode, producing electricity.  Volts are the units used to measure flow of electricity.

8. Voltage  You can determine the voltage by looking at the reduction potentials for the two half reactions/cells  Suppose I have a half reaction Zn  Zn 2+ + 2e - Looking up the reduction potential it is -0.76 But this is oxidation, so I reverse the sign, +0.76  Suppose I have the half reaction Cu 2+ + 2e -  Cu Looking up the reduction potential it is +0.34  The voltage for this cell should be 0.76 + 0.34 = 1.10 V

9. The Salt Bridge  The salt bridge allows ions to move into or out of the 2 half cells in order to keep the two half cells with neutral charges.

10. All together now http://chemwiki.ucdavis.edu/