1. Chapter 7 Electrochemistry
§7.9 Electrode potential and electromotive forces
H2O O2 H2 pH
 / V 2 4 6 8 10 12 14
0.401
-0.828
0.000
1.229

2. 7.9.1. Influential factors for electrode potential
1) emf’s and G of reaction in different forms
Exercise: Compare G1, G2, G3 and E1, E2, E3.
reaction:
H2 + Cu2+  Cu + 2H G1, E1
1/2 H2 + 1/2 Cu2+  1/2 Cu + H+ G2, E2
Cu + 2H+  H2 + Cu G3, E3

3. Give the relationship between 
2)  of electric couple between different oxidation state
Give the relationship between 
Fe3+
Fe2+ Fe
Exercise

4. 3)  of different electrode
AgCl = Ag+ + Cl-
Ag(s)|AgNO3(c1) ||KCl(c2) |AgCl(s)|Ag(s)
Exercise:
deduce the relationship between
and

5. Nernst equation 7.9.2. Concentration-dependence of 
for Ag+/Ag electrode
(Ag+/Ag) depends on [Ag+] , or (Ag+/Ag) responds to [Ag+]. The relationship between (Ag+/Ag) and [Ag+] can be used for quantitative electroanalysis of Ag+.

6. Can we use hydrogen electrode for measuring the pH of the solution?
Give the principle of the measurement.

7. 7.9.3. pH-dependence of  : Pourbaix diagram
For electrode reaction with H+ or OH- participating in, the electrode potential will depend on pH.
2H+ + 2e-  H2
H2O O2 H2 pH
 / V 2 4 6 8 10 12 14
0.401
-0.828
0.000
1.229
 = ⊖ lgaH+
= pH
O2 + 4H+ + 4e-  2H2O
 = ⊖ lgaH+
= pH
pH-potential diagram/Pourbaix diagram

8. Application of Pourbaix diagram
Cu2+
Cu(OH)2 Cu pH
 / V 2 4 6 8 10 12 14
CuO22
Cu2O

9. Pourbaix diagram of iron-water system
Equilibrium line
Fe2+
Fe2O3 Fe pH
 / V 2 4 6 8 10 12 14
Fe3O4
Fe3+
FeO22
Stable zone
Stable state
Product
Reaction
Protection, passivation,
active dissolution,
electroplating,
electrosynthesis