how many moles of permanganate were used? [2] 4. how many moles of iron were required to react with the permanganate? [1] 5. what is the mass of iron present in the initial sample? [1] 6. what is the mass percent of iron in the unknown iron sample? [2] 7. a student performed the experiment and got a higher mass percent than expected. other than human error or machine malfunctions, briefly explain a source of error from the experiment.