1. Chapter 15 Notes
Oxidation number - number of electrons an element wants to gain or lose to become stable. Determining oxidation number:
Ex. CaSO4
CCl4
AlPO4

2. Chapter 15 Notes Reduction Vs Oxidation
Reduction – Called this because charge gets reduced (more negative) Gaining of electrons
Oxidation - Losing of electrons becomes more positive.
LEO the lion goes GER
When you have a reaction in which both reduction and oxidation occur is known as a redox reaction.

3. Chapter 15 Notes Cathode vs Anode
Cathode is where reduction occurs, builds up because metal ions gain electrons and become neutral metals (Metal plating)
Anode is where oxidation occurs and the electrode will break down into ions in solution.
Electrode is the part of the conductor that touches the solution
An Ox Loses…Red Cats Gain

4. Chapter 15 Notes There are two big topics in electrochemistry:
Electrolysis—in which electricity (moving electrons) causes chemical change
Electrochemical Cells—in which chemical changes cause a flow of electrons (electricity).
When water undergoes electrolysis (memorize how to derive these). (-) cathode: 2 H2O(l) + 2 e-  H2(g) + 2 OH- (+) anode: 2 H2O(l)  O2(g) + 4 H+ + 4 e-

5. Chapter 15 Notes
You should be able to use a reduction potential chart to determine which of two substances are more likely to be reduced or oxidized.
Pg 585
Example Calculate the Cell Potential (voltage) for ZnlZn+2llCa+2lCa

6. Chapter 15 Notes
Draw a sample electrochemical cell