A 5.000 mL aqueous sample containing hydrogen peroxide was diluted to 25 mL and analyzed by titration with permanganate:
2 MnO₄^-(aq) + 5 H₂O₂(aq) + 6 H⁺(aq) → 5 O₂(g) + 2 Mn²⁺(aq) + 8 H₂O(l)
The sample required 42.8 mL of 0.0175 M permanganate to reach the end point.What is the concentration of hydrogen peroxide in the original sample?

Question

Quizplus · Accepted Answer

The moles of permanganate used are calculated by multiplying its volume (in liters) by its molarity: 0.0428 L * 0.0175 M = 0.000749 mol. From the balanced equation, 2 moles of permanganate react with 5 moles of hydrogen peroxide, so the moles of hydrogen peroxide are (5/2) * 0.000749 mol = 0.0018725 mol. Since the original sample was 5.000 mL, the concentration of hydrogen peroxide is 0.0018725 mol / 0.005 L = 0.375 M.

A 5000 ML Aqueous Sample Containing Hydrogen Peroxide Was Diluted to to 25