Question

In neutral or faintly alkaline solution, 8 moles of permanganate anion quantitatively oxidize thiosulphate anions to produce X moles of a sulphur containing product. Find the magnitude of X.

Answer 1

In a neutral or faintly alkaline solution, the permanganate anion \[\ce{(MnO^-_4)}\] is reduced to manganese dioxide (MnO₂), and the thiosulphate anion \[\ce{(S2O^{2-}_3)}\] is oxidized to the sulphate anion. The balanced chemical equation is as follows:

\[\ce{8MnO^-_4 + 3S2O^{2-}_3 + H2O -> 8MnO2 + 6SO^{2-}_4 + 2OH-}\]

From the balanced equation, we can establish the mole ratio between the reactants and products. The ratio of permanganate ions to the sulphur-containing product (sulphate ions) is 8 moles of \[\ce{(MnO^-_4)}\] to 6 moles of \[\ce{(S2O^{2-}_4)}\]