A 3.67 g sample of insecticide was decomposed in acid, any As5+ was reduced to As3+ and diluted to 250.0 mL in a volumetric flask. A 5.00 mL aliquot was added to 125.0 mL of 0.0500 M KI buffered to pH 7. A coulometric titration was carried out with electrically-generated I3-, which oxidized As3+ to As5+ according to the reaction.
As3+ + I3-→ 3I-+ As5+
The titration required 287 s at a constant current of 24.25 mA to reach the endpoint. Calculate the percentage of As2O3 (197.84 g/mol) in the insecticide