13.2 g of iron(III) alum were dissolved in water and reduced to an iron(II) ion solution zinc and dilute sulfuric acid. The mixture was filtered and the filtrate and washings we
made
up
to 500 cm in a standard volumetric flask. If 20.0 cm of this solution
required 26.5 cm of 0.0100 mol dm- KMnO4 for oxidation:
a) give the ionic equation for the reduction of iron(III) ions by zinc metal.
(b) Calculate the percentage by mass of iron in iron alum.​