Use the method of Exercise 67 to determine the volume of titrant required to reach the indicated pH values in the following titrations.

(a) 25.00 mL of 0.250 M NaOH titrated with 0.300 M HCl; pH = 13.00, 12.00, 10.00, 4.00, 3.00; 

(b) 50.00 mL of 0.0100 M benzoic acid titrated with 0.0500 M KOH: pH = 4.50, 5.50, 11.50 (Ka = 6.3 x 10^-5).

Exercise 67

Rather than calculate the pH for different volumes of titrant, a titration curve can be established by calculating the volume of titrant required to reach certain pH values. Determine the volumes of 0.100 M NaOH required to reach the following pH values in the titration of 20.00 mL of 0.150 M HCl: pH = (a) 2.00;(b) 3.50; (c) 5.00; (d) 10.50; (e) 12.00.  Then plot the titration curve.