Question

A 5.00 mL aqueous sample containing hydrogen peroxide was diluted to 25 mL and analyzed by titration with permanganate: 2MnO4 − + 5H2O2 + 6H+ → 5O2 + 2Mn2+ + 8H2O The sample required 42.8 mL of 0.0175 M permanganate to reach the endpoint. What is the concentration of hydrogen peroxide in the original sample?

Answer 1

The reaction equation is :

2MnO4- + 5H2O2 + 6H+ $\implies$ 5O2 + 2Mn2+ 8H2O

Mole ratio of 2MnO4- : 5H2O2

Is 2:5

Moles of MnO4- are:

0.0175×42.8/1000 = 0.000749

Moles of H2O2 from mole ratio is:

0.000749 ×5/2 = 0.00375 moles

Answer is 0.00375 moles