Chapter 6 Electrochemical Analysis
Chapter 6 Electrochemical Analysis
6.1 Introduction 1 Oxidation- reduction reaction Anode reaction Red =s Ox+ ne (6r-1) Cathode reaction Ox ne === Red (6r-2) Cell reaction expression Anode solution, (aox)II solution, (Red) Cathode
Anode reaction: Red === Ox + ne - Cathode reaction: Ox + ne - === Red 6.1 Introduction 1. Oxidation – reduction reaction Cell reaction expression Anodesolution,(Ox)solution, (Red) Cathode (6r-1) (6r-2)
For example: Zn ZnSO4,(xMol)I I CuSO4, (Mol)I Cu Anode:Zn、Zn2+2e (6r-3) Cathode: Cu2++ 2e Cu (6r-4)
For example: Zn ZnSO4,(xMol) CuSO4, (yMol) Cu Anode: Zn Zn2+ + 2eCathode: Cu2 + + 2eCu (6r-3) (6r-4)
2. Half-cell Potential For half-cell reaction Ared+ ne pAox (6r-5) Nernst equation E=E 0 +Rl In cox nF (6-1) red For a cell cells cathode E anode (6-2) If, Ecell >0: Primary Cell Ecell<0: Electrolyic Cell
2. Half-cell Potential For half – cell reaction : rAred + ne - pAOx Nernst equation: For a Cell: Ecell = Ecathode - Eanode If, Ecell > 0: Primary Cell Ecell < 0: Electrolyic Cell r red p o x nF RT E E ln 0 = + (6r-5) (6-1) (6-2)
3. The Types of Electrodes 1)Ametal in Equilibrium with its ions (Class I electrodes Ag+e←Ag (6r-6) E E RT n a (6-3) g 8 Ag Ag
3.The Types of Electrodes 1) A metal in Equilibrium with its ions (Class Ⅰelectrodes) Ag+ + eAg + = + + + F A g R T Ag Ag Ag E Ag E ln 0 (6r-6) (6-3)