Is anyone here able to help me or point me in the right direction? Iron ores often involve a mixture of oxides and contain both Fe 2+ and Fe 3+ ions. Such an ore may be analyzed for its iron content by dissolving it in an acidic solution, reducing all of the iron to Fe 2+ ions and then titrating with a standard solution of potassium permanganate until there is just a tinge of pingk color in the solution containing the iron ions. (hint: the permanganate ion is intensely purple and Mn 2+ is colorless.) After the titration was complete, permanganate would be reduced and Fe 2+ would be oxidized. A sample of iron ore weighing 0.3500g was dissolved in acidic solution, and all of the iron was reduced. The resulting solution was titrated with a 1.621x10^-2 Molar KMnO4 Solution. The titration endpoint was reached when 41.56 mL of the KMnO4 solution was used. Determine the mass percent of iron in the iron ore sample. What I am thinking is that I need to create two half reactions with FeO and Fe2O3 --> Fe 2+. So I go through that and I end up with half reactions of : 2H+ + FeO -> Fe2+ + H2O 2e- + 6H+ + Fe2O3 -> 2Fe2+ + 3H2O and then combine it to form 8H+ + 2e- + FeO + Fe2O3 --> 3Fe2+ + 4H2O From what I've learned you are supposed to be able to cancel out the electrons when you combine the two half reactions, however in this case I only have electrons on one of the half reactions and thus I have no hope of canceling them out. Am I thinking about this correctly or is there something else I should be doing?