This document provides an overview of oxidation-reduction (redox) reactions including: 1. Defining oxidation as the loss of electrons and reduction as the gain of electrons. 2. Explaining that the reducing agent is oxidized and the oxidizing agent is reduced in redox reactions. 3. Detailing that the first step in understanding redox reactions is determining the oxidation number of each element in a compound.

1. Oxidation-Reduction
Reactions
1. Review the Activity Series we used
with single replacement reactions
2. Oxidation is the loss of electrons
3. Reduction is the gain of electrons
4. The Reducing Agent is oxidized
5. The Oxidizing Agent is reduced

2. Calculating Oxidation Number
The first step in better understanding redox
reactions is the determination of the
oxidation # of each element in a compound.
(+2)
(+1) (-2)
H 2 0
When determining oxidation numbers, look for
oxygen (-2) or hydrogen (+1). Group I and II
metals are also a good bet (+1 or +2). Halogens
like fluorine, chlorine, bromine, and iodine
(usually –1) are consistent, especially if paired
with a metal.

3. Determine the oxidation
numbers of the following:
MnO4-1
NO3-1
H2SO4
AgNO3
HClO
NaCl
BaF2
K2Cr2O7

4. A Few Reactions...
Cu(NO3)2
+
Ni
Ni(NO3)2
+
Cu
Pb
+
PbO2
+
H2SO4
PbSO4
+
H2O
Na
+
H2O
NaOH
+
H2
1.
Put oxidation #’s above each element
2.
Find the element oxidized (lose electrons)
3.
Find the element reduced (gain electrons)
Voltaic Cell

5. Batteries and Galvanic Cells:
Applications of Redox
Reactions.
•
Fuel cells for
cars
•
Power for
personal
electronic Lithium ion batteries
devices (cell
phones, etc)

6. The Anatomy of a Battery
Do a diagram of a battery made from aluminum and
silver.
1. Electrodes
2. Solutions
3. Salt bridge
4. Direction of e- flow
5. Voltage
6. Label anode and cathode, as well as the +/-
electrodes
Importance of the salt bridge- as Al Al+3 + 3e- ….
the electrons leave the anode and go to the cathode.
This leaves a buildup of Al+3 ions that could interfere
with the flow of electrons to the cathode. The salt
bridge allows NO3-1 ions to flow from the cathode to
the anode to balance the build up of Al+3.