KINETICS OF THE MANGANESE(III) - OXALATE REACTION IN ACIDIC SULFATE MEDIA

The kinetics of the reaction of manganese(III) with oxalic acid (OA) has been studied in H2SO4 solutions. Under the experimental conditions of 6 x 10(-3) < [OA]0 < 0.4 mol dm-3 and [H2SO4]0 greater-than-or-equal-to 0.2 mol dm-3 the observed pseudo-first order rate constant k(obs) follows the expression k(obs) = k1 + k2K2[C2O42-]/{1 + K2 [C2O42-]} where k1, k2 and K2 have been estimated by a non-linear least-squares method. The kinetics of this component reaction of the BZ type oscillation system with oxalic acid was influenced by the addition of HSO4-, SO42- and ClO4-ions. Oxalate complexes of manganese(III) decompose by a net process that can be generalized as 2Mn(III) + C2O42---> 2Mn(II) + 2CO2.