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1. ( 15 pts. ) Name ____________________ The absorption of drug molecules such a

ID: 849543 • Letter: 1

Question

1. (15 pts.)

Name ____________________

The absorption of drug molecules such as aspirin (acetylsalicylic acid) depends on their ability to penetrate nonpolar cell membranes. A large KP value indicates that the drug is able to do this efficiently. AH2O ? Amembrane

[A]membrane KP = ????????

[A]H2O

A. Aspirin has a carboxyl group with a pKa = 3.5 Calculate the exact percent of the drug in the uncharged (neutral) form at pH = 2. Calculate exactly the KP value in the stomach at pH = 2. Explain your reasoning and any simplifying assumptions. Show all work.

B. If the large intestine has a pH = 5.5, estimate the percent in the uncharged form at this pH. What do you predict will be the ?G

Explanation / Answer

kp=57