90. Solving a chemistry problem

1. When determining the calcium content in milk, 50.00 cm3 of milk was titrated with a working solution of a complexone with a molar concentration equivalent of 0.0830 mol/dm3. The following results of potentiometric titration were obtained:
Vset, cm3 0 5 10 15 17 18 19 20 21 24
E, mV 260 276 288 312 320 440 450 455 460 463
Build an integral curve based on the results of titration in coordinates (Е-V), calculate the calcium content in mg/dm3. Write an equation for a chemical reaction, suggest electrodes for this titration.