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The kinetics of the interaction of MnO₂, Mn₂O₃, and Mn₃O₄, with sulphuric acid solutions and the effect of oxalic acid on this process are studied. As the sulphuric acid concentration is increased from 0.1 to 5 N, the dissolution rate of Mn₂O₃, Mn₃O₄ to MnO₂ and Mn²⁺ ions decreases, whereas it increases with the concentration of Mn²⁺ ions. Upon the addition of H₂O_x, the complete dissolution of Mn₃O₄ occurs more quickly. The reaction order with respect to the H⁺ and O _x^2- ions is +0.5 ± 0.1. A mechanism of MnO₂ dissolution promotion by O _x^2- is proposed. The dissolution rate was found to depend on the concentrations of MnHO_x ^- ions and was highest at pH 1.6 ± 0.2. A rate law and mechanism are suggested for manganese oxides dissolution.

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