Ok, so i have this question i'm doing for revision and i am a bit stuck. The answer on it's own is a bit useless though, i need more how to get to it and why. Anyway, here's the question:
A solution contains iron (ii) and iron (iii) sulphates, 20cm3 of this solution just reduced 19.5cm3 of 0.0200 M Potassium Manganate (vii) in acid solution. After reduction (complete), a further 20cm3 of the solution required 28.7cm3 of the potassium manganate (vii). Calculate the concentration of each sulphate in g.1-1 present in the original solution.
I've started by getting the number of moles of manganate from the first reduction, if that's remotely correct.