Question

Using

0.200 ml H2O2

10 mL H2SO4 (aq) 1 M

Solution titrated with KMnO4(aq) 0.20M

In the reaction of the redox pairs MnO4- | Mn2+ and H2O2 | O2. Show reaction scheme and calculate the formal concentration c(H2O2)

Answer 1

When Solution acidified by H2SO4:
2MnO₄^- + 5H₂O₂ + 6H⁺ --> 2Mn²⁺ + 5O₂(g) + 8H₂O(l)
2 KMnO₄ + 5 H₂O₂ + 3 H₂SO₄ ====> K₂SO₄ + 2 MnSO₄ + 8 H₂O + 5 O₂

To calculate the concentration of H2O2 we need volume of KMnO4 .

7.9 ml of 0.2 M KMnO4 = 7.9 x 0.2 / 1000 = 0.00158 Moles

0.00158 Moles of KMnO4 that reactes with (0.00158 x 5/2) 0.00395 Moles of H2O2

0.00395 Moles of H2O2 = 0.00395 x 1000 / 0.2 = 1.975 M

1.975 M for 100% H2O2

Hence for 35% = 100 x 1.975 / 33 = 5.642 M

Concentration of H2O2 for 35% solution = 5.642 M