1. Electrolysis

2. Water Molecules
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 8

3. The decomposition of two water molecules.
Diatomic Diatomic
oxygen molecule hydrogen molecules +
Electric
current
2 H2O  O H2

4. Electrolysis H2O(l) O2 (g) + 2 H2 (g) “electro” = electricity
Water
Hydrogen
gas forms
Oxygen
Electrode
Source of
direct current
Electrolysis
“electro” = electricity
“lysis” = to split
*H1+
H2O(l) O2 (g) H2 (g)
water oxygen hydrogen
This demonstration needs to be done using DC current (to produce a 2:1 H:O ratio).
Use of AC current will produce equal amounts of hydrogen and oxygen gas.
*Must add acid catalyst
to conduct electricity
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 32

5. Electrolysis of Water Half reaction at the cathode (reduction):
4 H2O e -  2 H OH 1-
Half reaction at the anode (oxidation):
2 H2O  O H e -