1. ELECTROCHEMICAL CELLS

2. TASK Sequence these elements starting from the most reactive to the least reactive: Na, Pt, Au, C, H, Sn, Pb, Al, C, Mg, Li, Ca, Zn, Fe, Cu, Ag

3. TASK….answer Sequence these elements starting from the most reactive to the least reactive: K, Na, Li, Ca, Mg, Al, C, Zn, Fe, Sn, Pb, H, Cu, Ag, Au, Pt

4. The more reactive metals are more easily oxidised. They are stronger reducing agents. http://www.chem.iastate.edu/group/Greenbo we/sections/projectfolder/flashfiles/redox/h ome.html

5. Non-Metals Similarly, the more reactive non-metals are stronger oxidizing agents. F 2 Cl 2 Br 2 I 2 Strongest oxidising agent, most readily becomes reduced Weakest oxidising agent, least readily becomes reduced

6. In a redox reaction…… During a redox reaction, the oxidant and reductant particles collide and energy changes take place when electrons are transferred. It is possible to physically separate the oxidants and reductants and transfer the electrons through an external circuit called a electrochemical cell (battery). oxidants reductants e-e-

7. ELECTROCHEMICAL CELLS GALVANIC (VOLTAIC CELL) -uses redox reaction to release energy -eg battery in ipods, cellphones, etc. ELECTROLYTIC CELL -consumes electrical energy to drive a redox reaction -eg electroplating, recharging battery.

8. GALVANIC CELLS 1. Electrode = metal strip 2. Half cell= electrode immersed in a solution 3. Takes 2 half cells to make a voltaic cell. 4. Connect the electrodes to an external circuit. 5. Connect the half cells with “salt bridge” to allow ions to move back and forth.

9. “salt bridge” Physically keeps the solution separated and forces the ions to move through the wires.

10. DANIELL CELL Oxidation occurs at the anode. (-) Electrode Reduction occurs at the cathode. (+) Electrode Electrons flows from anode to cathode ZnSO 4 CuSO 4

11. mneumonic REDCAT AN OX http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/galvan5.swf