Answer to Question #299840 in Chemistry for Wellen

Question

Solution X containing 0.020 mol of iron(II) sulfate requires 22.5 mL of potassium manganate(VII) for a complete reaction. The equation for the reaction is: 5Fe²⁺ + MnO^4- + 8H⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺. What is the molarity of the KMnO₄ solution? (5 Points)

Answer 1

Solution:

iron(II) sulfate = FeSO₄

FeSO₄ → Fe²⁺ + SO₄^2-

According to stoichiometry:

Moles of FeSO₄ = Moles of Fe²⁺ = 0.020 mol

Balanced chemical equation:

5Fe²⁺ + MnO₄^- + 8H⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺

According to stoichiometry:

5 mol of Fe²⁺ reacts with 1 mol of MnO₄^-

Thus, 0.020 mol of Fe²⁺ reacts with:

Moles of MnO₄^- = (0.020 mol Fe²⁺) × (1 mol MnO₄^- / 5 mol Fe²⁺) = 0.004 mol MnO₄^-

potassium manganate(VII) = KMnO₄

KMnO₄ → K⁺ + MnO₄^-

According to stoichiometry:

Moles of KMnO₄ = Moles of MnO₄^- = 0.004 mol

Molarity = Moles of solute / Liters of solution

Therefore,

Molarity of KMnO₄ = (0.004 mol) / (0.0225 L) = 0.178 M

Molarity of KMnO₄ = 0.178 M

Answer: The molarity of the KMnO₄ solution is 0.178 M