Page 11 - Pharmaceutical Analytical Chemistry II - Pharm D Clinical- 07-PA202
P. 11

The solution is kept saturated with hydrogen by bubbling H2 gas at

1.00 atm pressure over the surface the electrode.

Platinum electrode is Inert electrode, i.e. it takes no part in

electrochemical reaction, it serves only as site where electrons are

transferred.

It is reversible: acts either as anode or cathode depending on the

half-cell to which it is coupled.  H2 (g) E0 = 0.00 V

SHE reaction: 2H+ (aq) + 2e─

Schematic representation:

    Pt, H2 (p = 1.00 atm)  H+ (1.00 M) 

The potential of SHE is assigned a value of 0.00 V at all temp

To obtain: E0Ag                    Ag(s)

Half-reaction: Ag+ + e─

By measuring Ecell for the cell represented schematically as:
Pt, H2 (p = 1.00 atm)  H+ (1.00 M)  Ag+ (1.00 M)  Ag

E0cell = + 0.799 V, accordingly, E0Ag+/Ag = + 0.799 V

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