Given the following six solutions, each of which is 0.1 M, predict whether the solutions are acidic or basic. Be sure TO SHOW YOUR PROOF. Which solution is the most basic? Which solution is most acidic? Codeine. C18H21NO3, is a weak base. An aqueous solution of 0.0278 M codeine solution has a pH of 9.8. What is the Kb for codeine? What is the pH of a solution that is 0.132 M in diethylamine (CH3CH2)2NH and 0.145 M in diethylammonium chloride (CH3CH2)NH2Cl? The Kb for diethylamine is 6.9 x 10-4.