50. Solving a chemistry problem

3. A sample of a silver alloy weighing 2.157 g was dissolved and, after appropriate treatment, the volume of the solution was brought to 100.0 cm3. Construct titration curves in the coordinates E - V and dE / dV -V, and determine the mass fraction (%) of silver in the alloy, if titration of 25.00 cm3 of the prepared solution of 0.1200 M NaCl obtained:
VNaCl, cm3 16.00 18.00 19.00 19.50 19.90 20.00 20.10 20.50 21.00
E, mV 689 670 652 634 594 518 440 401 383