1. Better known as REDOX Lesson 1
Reduction/Oxidation
Better known as REDOX
Lesson 1

2. Oxidation and Reduction
Oxidation is the loss of electrons during a reaction (increase in charge).
Reduction is the gain of electrons during a reaction (decrease in charge).
LEO the lion says GER
OIL RIG (Oxidation Is
Losing electrons, Reduction
Is Gaining electrons)
Oxidation and reduction must always happen together. In a reaction one element is oxidized and another element is reduced.

3. Types of Redox Reactions
Synthesis and decomposition are all redox reactions.
Single replacement reactions will be redox if they happen.
Elements becoming compounds or compounds becoming elements always involve a change in oxidation number.

4. Oxidation Numbers (Ion Charge)
Elements not in compounds are always 0.
Hydrogen is +1.
Group 1 elements are +1.
Group 2 elements are +2.
Aluminum is +3.
Halogens are -1 (unless in polyatomic ion).
Oxygen is -2 (except in peroxide where it is -1).
The oxidation numbers of other elements can be figured using the above known ones.

5. Sample Problem
What is the oxidation number of each element in the following compounds:
(a) Al2O (b) Mg
(c) NaClO3 (d) Ca(NO3)2
(a) Al= +3, O= -2
(b) Mg= 0
(c) Na= +1, Cl= +5, O= -2
(d) Ca= +2, N= +5, O= -2

6. Sample Problem
Assign oxidation numbers to each element and identify the element that is oxidized and the element that is reduced in the following reaction:
3 H2S + 2 HNO3  3 S + 2 NO + 4 H2O
Oxidized: S
Reduced: N

7. Redox Agents The element oxidized is the reducing agent.
Common reducing agents are Na, K, Mg, Al, Zn, and Fe
The element reduced is the oxidizing agent.
Strong oxidizing agents usually contain F, O, or Cl

8. Practice—Assign Oxidation Numbers
As + NaOH ---> Na3AsO H2
C8H16 + Cl2 ---> C + HCl
Xe F > XeF6

9. Gummy Bear Explosion— Assign Oxidation Numbers What is Oxidized
Gummy Bear Explosion— Assign Oxidation Numbers What is Oxidized? What is Reduced?
KClO3 + C12H22O11 → H2O + CO2 + KCl
2KClO3 → 2KCl + 3O2
C12H22O O2 → 9C + 3CO2 + H2O
Oxidized: C, O Reduced: Cl, O