Quinine, C20H24N2O2, occurs naturally in the bark of thecinchona tree and was the first effective treatment for malaria. Itis a diprotic base with Kb values of (the acidic protons are shownin red) C20H24N2O2 + H2O HC20H24N2O2+ + OH- Kb2 = 1.0 × 10-6HC20H24N2O2+ + H2O H2C20H24N2O22+ + OH- Kb1 = 1.58 × 10-10

a) The recommended IV dose of quinine is 0.800 g/kg, that is,0.800 g of quinine per 1 kg of water. If we assume that the densityof the solution is 1.00 g/mL, what is the pH of this solution? Themolar mass of quinine is 324.412 g/mol. For simplicity, abbreviateC20H24N2O2 as Q.

b) 100 mL of the solution from part a is then titrated with asolution of 0.010 M HCl. How many mL of HCl solution is required toreach the first equivalence point?

c) What is the pH at the first equivalence point?

d) What is the pH when 32.00 mL of HCl has been added?

e) What is the pH at the second equivalence point?

f) Quantitatively draw the resulting titration curve on the axesbelow. Be sure to label both axes, equivalence points and bufferregions. Be as accurate as use can and make use of your results forparts a-e. g) The pH in the stomach is often quite low, between 2and 3. What species of quinine is predominant at a pH of 2.5?

h) The pH of blood is buffered at 7.4. What species of quinineis predominant at this pH?