Question

1.630 g of iron ore is dissolved in an acidic solution. This solution is titrated to a pink endpoint with 27.15 mL of a 0.020 M KMnO4 solution.

a. How many moles of MnO4- ions were consumed?

b. How many moles of Fe2+ were in the iron ore sample?

c. What is the percent of iron in the iron ore sample?

Answer 1

a. mols KMnO4 = M x L = about 0.00054 but you need to do that more accurately. Thjat's just an estimate.

b. 5Fe^2+ + MnO4^- ==> 5Fe^3+ + Mn^2+
Note that I balanced only the redox part to save a little time but that's all we really need to balance.
So mols Fe^2+ must be 5*mols MnO4^- = about 0.0027 mols Fe.

c. Convert mols Fe to grams Fe.
mols Fe x atomic mass Fe = approx 0.15
Then % = (g Fe/mass sample)*100 = ?

c.