1. Electrochemistry Lesson 2
Oxidation-Reduction Reactions

2. REDOX Solid zinc with a zero charge loses two electrons to become Zn2+
Zn (s) + Cu2+ (aq) → Cu (s) + Zn2+ (aq)
Solid zinc with a zero charge loses two electrons to become Zn2+
Cu2+ gains two electrons to become solid copper with a zero charge.
This is called an oxidation-reduction, or redox reaction.
Whenever there is a loss of electrons, it is called oxidation, therefore zinc is being oxidized.
Whenever there is a gain of electrons, it is called reduction, there copper is being reduced.
The amount of electrons lost by one element must be equal to the electrons that were gained by the other – they are being transferred from one atom to another.

3. Example 1
Pb (s) + Cu(NO3)2 (aq) →

4. Example 2
Cu (s) + 2 AgNO3 (aq) →

5. Example 3
2 Mg (s) + O2 (g) → 2 MgO (s)

6. Example 4
2 Na (s) + Br2 (g) → 2 NaBr (s)