Absorption of food in the stomach and intestine depends on the ability of molecules to penetrate the cell membranes and pass into the bloodstream. Because hydrophobic molecules are more likely to be absorbed than hydrophilic or charged molecules, the absorption of orally administered drugs may depend on their pKa values and the pH in the digestive organs. Aspirin (acetylsalicylic acid) has an ionizable carboxyl group (pKa= 3.5). Required:
Calculate the percentage of the protonated form of aspirin available for absorption in the stomach (pH= 2.0) and in the intestine (pH= 5.0).