2. Solving a chemistry problem

9. Construct a potentiometric titration curve in the coordinates ΔpH/ΔV—V and determine the mass of methylamine CH3NH2 in 100 ml of solution, if titration of 10.0 ml of the analyzed methylamine solution with a solution of hydrochloric acid (C=0.1053 mol/l) yielded the following results:
V(HCl), ml 5.00 7.00 9.00 9.50 9.90 10.00 10.10 10.50 11.00
pH 10.40 10.12 9.56 9.28 8.40 6.05 3.55 2.80 2.60