Studies on the Suppression of Polarographic Maximum of Mn(II) by Some uni- and poly-valent Cations vis-a-vis Their Influence on the Kinetics of the Electrode Reaction of Mn(II)

Department of Chemistry, Agra College, Agra-282 002

Manuscript received 13 July 1981, revised 17 March 1982, accepted 1 May 1982

Suppression of the polarographic maximum of Mn(II) in 0.05 M KCI, which falls in the category of the negative maximum of the first kind, has been attempted using some uni- and poly-valent metal cations, viz, Li⁺, Na⁺, K⁺, Bas²⁺, Sr²⁺, Ca²⁺, Mg²+, La³⁺, Nb³⁺ and Pr³⁺ as suppressors. The electrode reaction of Mn(II) has been found to be quasi-reversible in the presence of different amounts of these suppressors. The values of kinetic parameters (α and k_s,h) of quasi-reversible electrode reaction of Mn(II) have been calculated by Gellings' method. A decrease in the values of α and k_s,h with increasing concentrations of uni- and poly-valent cations shows that the quasi-reversible electrode reaction of Mn(II) tends towards irreversibility. On the basis of molarity, the order of relative efficacies of metal cations in the suppression of the negative maximum of Mn(II) has been established as M²⁺ > M²⁺ > M⁺.