Page 17 - Pharmaceutical Analytical Chemistry II - Pharm D- 02-06-07102

EXAMPLE 1

What is the potential for a half-cell consisting of a Cd electrode
immersed in a solution that is 0.010 M Cd2+?

Cd2+ + 2e– Cd(s) E0 = – 0.403 V

NOTE:

E0 = – 0.403 V, negative sign of SEP indicates that Cd electrode acts
Spontaneously as Anode relative to SHE
The Spontaneous Reaction: Oxidation
It acts as reducing agent

Decreasing the oxidized species [Cd2+] from 1.00 M (standard state) to
0.01 M resulted in increasing the magnitude of the potential, i.e. more
negative, i.e. stronger reductant

EXAMPLE 2

Calculate the potential, E, at which Cl2 gas is liberated at an inert
electrode immersed in a 0.05 M solution of NaCl assuming that the

gas is formed at 740 mmHg pressure (E0Cl2/Cl- =+1.36 V)
Cl2 (g) + 2e– 2Cl –
E0 = 1.36 V

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