Question

Diazepam is a weakly basic (pKb = 10.6) sedative used to treat severe anxiety disorders. For analysis of
the diazepam content of a generic brand pill, a titration is carried out with strong acid. It takes 40.00
mL of 0.110 M acid to reach the stoichiometric point. The initial diazepam concentration is 0.02933 M
and the solution volume is 150.0 mL.

Calculate the pH of this solution at the following points:

a) Initial pH.

b) After addition of 18.00 mL of acid.

c) After addition of 20.00 mL of acid solution. (1 mark)

d) At the stoichiometric point.

e) After addition of 60.0 mL acid solution.

f) Choose an indicator from Table 16.2 of the textbook (Chapter 16, slide 30) that would be most
appropriate for this titration. (1 mark)

Answer 1