A STUDY OF THE STABILITY OF MN(III) AND ITS REDOX REACTION WITH CO(II) IN AQUEOUS AZIDE MEDIUM

Mn(III) was generated in a coulometric cell by the oxidation of Mn(II) in azide medium at 2 M ionic strength and 22-degrees-C. The system exhibited an excellent Nernst behaviour. The interaction of Mn(II/III) with Co(II/III) according to the overall reaction Co(III) + Mn(II) reversible Co(II) + Mn(III) was studied as a function of azide concentration. The equilibrium constant for this reaction increases from 0.0239 at 2 M azide to 0.0289 at 0.1 M azide. Kinetic measurements were also performed to measure the forward and reverse rate constants for the equilibrium which resulted in an equilibrium constant of 0.0175 at 1 M azide. The results are discussed in reference to the catalytic role of Mn(II/III) in the sulfite catalyzed autoxidation of Co(II).