Question

A 0.0484 M standard solution of potassium
permanganate was titrated against 25.00 mL of an iron
(II) sulfate solution. The equivalence point, as indicated
by a faint pink colour, was reached when 15.50 mL of
potassium permanganate solution had been added.
Calculate the concentration of the iron(II) sulfate
solution.

Answer 1

The balanced chemical equation for the reaction between potassium permanganate (KMnO₄) and iron(II) sulfate (FeSO₄) is:

5FeSO₄ + 2KMnO₄ + 3H₂SO₄ → 5Fe₂(SO₄)₃ + 2MnSO₄ + K₂SO₄ + 3H₂O

From the balanced equation, it can be seen that the mole ratio of FeSO₄ to KMnO₄ is 5:2.

Using the information given in the question, we can calculate the number of moles of KMnO₄ used:

Moles of KMnO₄ = Molarity x Volume (L)
Moles of KMnO₄ = 0.0484 mol/L x 15.50 mL / 1000 mL/L
Moles of KMnO₄ = 0.00075 mol

Since the mole ratio of FeSO₄ to KMnO₄ is 5:2, the number of moles of FeSO₄ in the reaction can be calculated as:

Moles of FeSO₄ = 5/2 x Moles of KMnO₄
Moles of FeSO₄ = 5/2 x 0.00075 mol
Moles of FeSO₄ = 0.001875 mol

Now, we can calculate the concentration of the iron(II) sulfate solution:

Concentration of FeSO₄ = Moles / Volume (L)
Concentration of FeSO₄ = 0.001875 mol / 25.00 mL / 1000 mL/L
Concentration of FeSO₄ = 0.075 M

Therefore, the concentration of the iron(II) sulfate solution is 0.075 M.