Kinetics of the manganese(III)-oxalate reaction in acidic sulphate media

Abstract

The kinetics of the reaction of manganese(III) with oxalic acid (OA) has been studied in H2SO4 solutions. Under the experimental conditions of 6 × 10−3 < [OA]0 < 0.4 mol dm−3 and [H2SO4]0 ⩾ 0.2 mol dm−3 the observed pseudo-first order rate constant kobs follows the expression $$k_{obs} = k_1 + k_2 K_2 \left[ {C_2 O_4^{2 - } } \right]/\left\{ {1 + K_2 \left[ {C_2 O_4^{2 - } } \right]} \right\}$$ 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 HSO f4 p− , SO f4 p2+ and ClO f4 p− ions. Oxalate complexes of manganese(III) decompose by a net process that can be generalized as 2MnIII + C2O f4 p2− → 2MnII + 2CO2.