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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 H 2 SO 4
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Mitsubishi iMiEV - Pure Electric Car Powered by a 330 v Li-Ion Rechargeable battery Plugs into your house and takes 14 hours to charge -100 km for $ 0.60 $ 50,000 Can $ 36,000 US 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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voltmeter 1. Draw and completely analyze a Cu/Sn electrochemical cell. Higher Greatest Electron Affinity Reduction Cathode Cu 2+ + 2e - → Cu (s) 0.34 v Gains mass + Cu Sn Cu 2+ NO 3 - Sn 2+ NO 3 - Na -+ NO 3 - 0.48 v Lower Oxidation Anode Sn (s) → Sn 2+ + 2e - +0.14 v Loses mass - Overall Reaction: Cu 2+ + Sn → Sn 2+ + Cu (s) 0.48 v e-e- e-e-
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The Hydrogen half cell involves a gas and requires an inert or nonreactive Pt electrode. H 2(g) in Wire to circuit Pt (s) 1 M HCl H + Cl -
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1.0 M KNO 3 0.80 v Ag H2H2 voltmeter 2e - H + Cl - Ag + NO 3 - NO 3 - K + 2Ag + + H 2 → 2Ag + 2H + 0.80 v Draw a H 2 /Ag electrochemical cell with a KNO 3 salt bridge. Higher Greater electron affinity Reduction Cathode + Ag + + 1e - → Ag (s) +0.80 v Gains mass oxidation Anode - H 2 → 2H + + 2e - 0.00 v pH decreases 1 M HCl 1 M AgNO 3 Pt
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