21. Solving a chemistry problem

1. A sample of an iron-containing preparation weighing 0.3241 g was dissolved in acid without access of air, transferred to a capacity of 200 ml and the volume was adjusted to the mark. An aliquot of the resulting solution (10 ml) was taken, placed in a titration beaker, and iron (II) was titrated potentiometrically with a 0.0500 N solution of KMnO4. Based on the results obtained
V, ml 2.5 2.6 2.7 2.8 2.85 2.9 3.0
E, mV 585 570 550 530 410 180 170
construct integral and differential titration curves and calculate the mass fraction of iron in the preparation.