20 mL of a solution containing 0.2 g of impure sample of H2O2 reacts with 0.316 g of KMnO4 in presence of H2SO4. What is the % purity of H2O2?
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Solution
The redox reaction is as follows:
2MnO4−+5H2O2→5O2+2Mn2+ The number of moles of KMnO4 present =0.316158=2×10−3 mol The number of moles of pure H2O2=52×2×10−3=5×10−3 0.2 g of sample contains 0.17 g of pure H2O2. Therefore, percentage purity of H2O2=0.170.2×100=85%