What is the pH of an aqueous solution that contains 0.226 M potassium hydrogen phosphate, K2HPO4, and 0.451 M potassium dihydrogen phosphate, KH2PO4? (Ka for H3PO4 = 7.52 × 10−3 , Ka for H2PO4 − = 6.23 × 10−8 , Ka for HPO4 2− = 4.8 × 10−13)that the solution originally contained 0.125 moles of quinine. What was the pH of the solution after50.00 mL of the HCl solution were added? Quinine is monobasic with pKb = 5.10.