Electrochemistry Lesson 8 Electrochemical Cells Electrochemical cells are

Electrochemistry Lesson 8 Electrochemical Cells

Electrochemical cells are Batteries

Alkaline Batteries KOH

Car Batteries Pb-Acid H 2 SO 4

Mitsubishi i. Mi. EV - 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

Cell Phone batteries Lithium Ion Rechargeable battery

Lithium Coin Cell

Space Ship Batteries Powered by Radioisotopes

Ni-Metal Hydride

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. 1. 2. 3. Spontaneous redox reaction Produces electricity from chemicals Is commonly called a battery The salt bridge allows ions to migrate from one half-cell to the other without allowing the solutions to mix.

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.

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

1. Draw and completely analyze a Cu/Sn electrochemical cell. voltmeter e- Higher e- 0. 48 v Greatest Electron Affinity Lower Reduction Oxidation Cathode Na-+ NO 3 - Sn Cu Anode Sn(s) → Sn 2+ + 2 e- Cu 2+ + 2 e- → Cu(s) 0. 34 v Cu 2+ Sn 2+ +0. 14 v Gains mass NO 3 - Loses mass - + Overall Reaction: Cu 2+ + Sn → Sn 2+ + Cu(s) 0. 48 v

The Hydrogen half cell involves a gas and requires an inert or nonreactive Pt electrode. Wire to circuit H 2(g) in H+ Cl. Pt(s) 1 M HCl

Draw a H 2/Ag electrochemical cell with a KNO 3 salt bridge. voltmeter 2 e 2 e- 0. 80 v 1. 0 M KNO 3 oxidation Anode - H 2 → 2 H+ + 2 e. Pt 0. 00 v p. H decreases Ag NO 3 - K+ H+ Ag+ Cl- NO 3 - 1 M HCl 2 Ag+ + H 2 → 2 Ag + 2 H+ Higher Greater electron affinity Reduction Cathode + Ag+ + 1 e- → Ag(s) +0. 80 v Gains mass 1 M Ag. NO 3 0. 80 v