Chemical and electrochemical properties of manganese in water+sodium hydroxide and water+potassium hydroxide mixtures at 25°C

Experimental study of the solubility of Mn(II) and Mn(III) was carried out by polarography in water+hydroxide mixtures at 25°C. This method also permitted determination of the standard potential of the Mn(II)/Mn(III) electrochemical system as a function of the composition of the medium. These measurements were supplemented by a voltammetric study carried out with a carbon-paste electrode. The results obtained, combined with published thermochemical data, permitted the construction of potential-composition diagrams (analogous to diagrams of Pourbaix for aqueous solutions), thus identifying the properties of manganese in water+sodium hydroxide and water+potassium hydroxide mixtures.