Equilibrium Question 512
Question: The $ pK_{a} $ of acetylsalicylic acid (aspirin) is 3.5. The $ pH $ of gastric juice in human stomach is about 2-3 and the $ pH $ in the small intestine is about 8. Aspirin will be [IIT 1988; KCET 2003]
Options:
A) Unionized in the small intestine and in the stomach
B) Completely ionized in the small intestine and in the stomach
C) Ionized in the stomach and almost unionized in the small intestine
D) Ionized in the small intestine and almost unionized in the stomach
Show Answer
Answer:
Correct Answer: D
Solution:
Aspirin is a weak acid. Due to common ion effect it is unionised in acid medium but completely ionised in alkaline medium.
