16. Solving a chemistry problem

5. A weighing of the adjusting substance of sodium carbonate weighing 0.2500 g was dissolved in a volumetric flask with a capacity of 50 ml and the solution was brought to the mark with glacial acetic acid. Potentiometric titration of 5 ml of the resulting solution with perchloric acid in anhydrous acetic acid gave the following results:
V(HClO4), ml 3.60 3.80 4.00 4.20 4.40 4.60 4.80 5.00 5.20
E, mV 431 439 450 465 486 523 550 566 575
Construct a titration curve in the coordinates ΔE / ΔV - V and calculate the molar concentration of the sodium carbonate equivalent of the perchloric acid solution.