075. Solving a chemistry problem

9. A steel sample weighing 0.5000 g was dissolved in a beaker, then transferred to a 100 ml volumetric flask. 25 ml of this solution was placed in the electrolyzer and at a potential of 1.7 V against the background of sodium acetate, amperometric titration of nickel with dimethylglyoxime (DMG) was performed with T(DMG/Ni) = 2 mg/ml. Determine the mass fraction of nickel in steel if the following data are obtained during titration:
Titrant volume, ml 0.1 0.15 0.2 0.3 0.4 0.5
Current, mAK 37 28 20.5 18 30 41.5
DMG and nickel react in a molar ratio of 2:1.