Construct potentiometric titration curves in the coordinates E-V and ΔE / ΔV and calculate the CaCl2 concentration in the solution (g / l) if, when titrating 20 ml of the analyzed solution, 0.05 N Hg (NO3) 2 (feq = 1/2) received:

V (Hg (NO3) 2), ml 10.00 15.00 18.00 19.00 19.50 19.90 20.00 20.10 20.50

E, mV 501 526 552 570 589 629 704 737 757