The titration of 25 mL of pyrimidine 0.0836 mol / L (Kb = 1.69 x10) with HCl

The titration of 25 mL of pyrimidine 0.0836 mol / L (Kb = 1.69 x10⁻⁹) with HCl 0.1067 mol / L. Tit ration reaction: C₅H₅N + H⁺ → C₅H₅NH⁺.

 a) calculate the pH when the volume of acid added is 4.63; 19.60 and 25.00 mL; 

b) Sketch the titration curve using the data found in item an as the basis; 

c) If the concentrations of the reagents involved were less concentrated, what would you expect to happen? (justify and sketch the two curves on the same graph).