Question

When 25.0 ml of a solution containing both Fe2+and Fe3 +ions is titrated with 23.0 ml of 0.0200M KMnO4(in dilute sulphuric acid), all the Fe2+ are oxidised to Fe3+ ions. Next, the solution is treated with Zinc metal to convert all the Fe3+ ions to Fe2+ ions. Finally 40ml of the same Kmno4 solution is added to the solution oxidise the Fe2+ to Fe3.Calculate the molar concentrations of Fe2+ and Fe3 + in the original solution
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23M