A 5.0 g sample containing Pb3O4, PbO2 and some inert impurity is dissolved in 250 mL dil. HNO3 solution and 2.7 g of Na2C2O4 was added so that all lead converted to Pb2+. A 10 mL portion of this solution required 8.0 mL 0.02 M KMnO4 for titration of excess of oxalate. In an another experiment 25 mL of solution was taken and excess oxalate was removed by extraction, this required 10 mL of a permanganate solution for oxidation of Pb2+ to Pb4+. 10 mL of this permanganate solution is equivalent to 4.48 mL 5 V H2O2 solution. Calculate mass % of PbO2 and Pb3O4 in the original sample.[Atomic mass of Pb = 207]

Prathamesh Tamhane , 15 Years ago

Grade 11