12. Solution to Chemistry Problem

1. A 6.39 g sample containing arsenic was decomposed by the wet method with H2SO4 and HNO3. The residue of arsenic was reduced with hydrazine to oxidation state +3. After removing excess reducing agent, As(III) was oxidized with electrogenerated iodine in a weakly alkaline medium: HASO32-+J2+2HCO3-→HAsO42-+2J-+2CO2+H2O. The titration was completed after passing a current of 98.3 mA for 13 min 12 sec. Find the % content of As2O3 in the original sample.