11. Solving a chemistry problem

9. Titration of sodium thiosulfate, used as an auxiliary solution for the determination of copper ions in Fehling´s reagent, was carried out with iodine electrogenerated from an acetate buffer solution containing 1.66 g of KI using a KTT biamperometric display system. After pre-electrolysis of KI, when the potential of the indicator system was 40 mV, 2 cm3 of 0.1 N sodium thiosulfate solution was placed in the coulometric cell and titrated at a constant current of 50 mA. How much time was spent on the analysis?