Page 7 - Pharmaceutical Analytical Chemistry II - Pharm D Clinical- 07-PA202

A single vertical line indicates a phase boundary or interface at which a
potential develops "Electrode Potential"

ZnZnSO4 Anode potential: Potential develops at a phase boundary

between Zinc electrode and Zinc sulfate solution

A double vertical line represents two phase boundaries, one at each
end of the salt bridge, at which a "Liquid Junction Potential" develops

Anode is assigned as left-hand electrode
Cathode is assigned as right-hand electrode
( ) activity

TYPES of ELECTRODES "Half-Cell"

1. INERT Electrode:

It does not share in electrode reaction. It acts as a conductor of
electrons ---- to allow measuring of electrode potential
Example: Pt, gold,graphite,..It is used in the following electrode half cell:

• Gas electrode,
E.g. Hydrogen electrode H2 gas/H+

Pt, H2 (p = ? atm) H+ (1.00 M) 

• Metal ions in different oxidation states Fe3+/ Fe2+

PtFe3+ (?M) , Fe2+ (?M) 

• Non-Metal ions in different oxidation states

PtClO4─ (?M), Cl─ (?M) 

2. METAL / METAL ION Electrode,

Ag/Ag+ AgAg+ (x M) 
Zn/Zn2+ ZnZn2+ (x M) 

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