258. In a weak solution of H2SO4 dissolved 2.792 g of iron ore. In the process of dissolving the iron turned into FeSO4. The interaction FeSO4 c 23 ml 1 N KMnO4 solution is completely shifted to Fe2 (SO4) 3 according to the reaction equation:
FeSO4 + KMnO4 + H2SO4 Fe2 (SO4) 3 + MnSO4 + K2SO4 + H2O.
Write the material and the electron balance equation and determine the percentage of iron in the ore