Chemical and Ionic Equilibrium 2 Question 25
25. The $\mathrm{p} K_{a}$ of acetyl salicylic acid (aspirin) is 3.5 . The $\mathrm{pH}$ of gastric juice in human stomach is about 2-3 and the $\mathrm{pH}$ in the small intestine is about 8 . Aspirin will be
$(1988,1 \mathrm{M})$
(a) unionised in the small intestine and in the stomach
(b) completely ionised in the small intestine and in the stomach
(c) ionised in the stomach and almost unionised in the small intestine
(d) ionised in the small intestine and almost unionised in the stomach
Show Answer
Solution:
- In stomach, $\mathrm{pH}$ is $2-3$, i.e. strongly acidic and aspirin will be almost unionised here due to common ion effect. However, $\mathrm{pH}$ in small intestine is 8 , basic, aspirin will be neutralised here.
