The pH value of gasfric juice in humna stomach is about 1.8 and in intiestine , it is about 7.8. The `pk_(a)` value of aspirin is 3.5 Aspirin will be

Options

A. Ionised in the small intestine and almost unionised in the stomach
B. Ionised in the stomach and almost unionised in the small intestine
C. Completely ionised in the small intestine and in the stomach.
D. Unionised in the small intestine and in the stomach.

Answer

A

Explanation

`pK_(a)=3.5`
`log K_(a)=3.5`
`K_(a)=10^(-3.5)`
Thus, `K_(a)` of aspirin is quite small. As such it is a weak acid. In the presence of a strong acid is gastric unionised. However, in the small intestine, when medium is slightly alkaline `(pH =7.8)` it will be ionised.