1. A. Oxidation-Reduction Reactions
Oxidation-reduction reaction (Redox) a chemical reaction involving the transfer of electrons
Oxidation – loss of electrons
Reduction – gain of electrons

2. A. Oxidation-Reduction Reactions
Which element is oxidized?
Which element is reduced?

3. A. Oxidation-Reduction Reactions Between Nonmetals
2Na(s) + Cl2(g)  2NaCl(s)
Na  oxidized
Na is also called the reducing agent (electron donor).
Cl2  reduced
Cl2 is also called the oxidizing agent (electron acceptor).

4. B. Electrochemistry: An Introduction
Electrochemistry – the study of the interchange of chemical and electrical energy
Two types of processes
Production of an electric current from a chemical reaction
The use of electric current to produce chemical change

5. B. Electrochemistry: An Introduction
Making an electrochemical cell

6. B. Electrochemistry: An Introduction
If electrons flow through the wire charge builds up.
Solutions must be connected to permit ions to flow to balance the charge.

7. B. Electrochemistry: An Introduction
A salt bridge or porous disk connects the half cells and allows ions to flow, completing the circuit.

8. B. Electrochemistry: An Introduction
Electrochemical battery (galvanic cell) – device powered by an oxidation-reduction reaction where chemical energy is converted to electrical energy
Anode – electrode where oxidation occurs
Cathode – electrode where reduction occurs

9. C. Batteries
Lead Storage Battery
Anode reaction - oxidation
Pb + H2SO4  PbSO H e
Cathode reaction - reduction
PbO2 + H2SO e + 2H+  PbSO H2O

10. C. Batteries
Overall reaction
Pb + PbO2 + 2H2SO4  2PbSO H2O

11. Dry Cell Batteries – do not contain a liquid electrolyte
C. Batteries
Electric Potential – the “pressure” on electrons to flow from anode to cathode in a battery
Dry Cell Batteries – do not contain a liquid electrolyte
Acid version
Anode reaction - oxidation
Zn  Zn e
Cathode reaction – reduction
2NH4+ + 2MnO e  Mn2O NH3 + 2H2O

12. Dry Cell Batteries – do not contain a liquid electrolyte
C. Batteries
Dry Cell Batteries – do not contain a liquid electrolyte
Alkaline version
Anode reaction - oxidation
Zn + 2OH  ZnO + H2O + 2e
Cathode reaction – reduction
2MnO2 + H2O + 2e  Mn2O OH

13. Dry Cell Batteries – do not contain a liquid electrolyte
C. Batteries
Dry Cell Batteries – do not contain a liquid electrolyte
Other types
Silver cell – Zn anode, Ag2O cathode
Mercury cell – Zn anode, HgO cathode
Nickel-cadmium – rechargeable

14. D. Corrosion
Corrosion is the oxidation of metals to form mainly oxides and sulfides.
Some metals, such as aluminum, protect themselves with their oxide coating.
Corrosion of iron can be prevented by coatings, by alloying and cathodic protection.
Cathodic protection of an underground pipe

15. E. Electrolysis
Electrolysis – a process involving forcing a current through a cell to produce a chemical change that would not otherwise occur