Studies on the complexes of chromium(II) chloride with some amino acids

✍ Scribed by Omar Farooq; Anees Uddin Malik; Naseer Ahmad

• Publisher: Elsevier Science
• Year: 1970
• Weight: 218 KB
• Volume: 24
• Category: Article
• ISSN: 0022-0728
• DOI: 10.1016/s0022-0728(70)80027-4

✦ Synopsis

equiv, depolarizer, the oxidation wave of hydroquinone attains its limiting height when four alkali hydroxide equivalents (NaOH or LiOH) are added to the solution. Since the wave is diffusion-controlled, a kinetic reaction is ruled out. It is probable that alkali hydroxides in pure non-aqueous methanolic solutions are present in dimeric associations, for which the equilibria: (M OH)2 ~ 2 MOH ~ 2 M + + 2 OHare governing. Accordingly, the activity of OH-in the medium would depend on the square root of the analytical concentration of the alkali hydroxide.

The results of the present investigation reveal that the quinone-hydroquinone system in non-aqueous methanol behaves irreversibly. Only one of the two electrode reactions is recorded, depending upon whether the medium acts as proton donor or acceptor. In the presence of proton acceptors, the half-wave potential of the oxidation wave of hydroquinone is more positive than the corresponding value of the reduction wave of quinone, even in absence of proton donors. This reveals that the cause of irreversibility is mainly the result of a retarded anodic reaction.