Answer:
The protonated form is predominant when aspirin is absorbed more readily. The ratio of conjugate base to acid is 1 to 100.
Explanation:
Aspirin is more readily absorbed when it is protonated, that is when pH is lower than pKa (more H⁺ available in the medium). We can confirm this using Henderson-Hasselbalch equation for pH = 1.5:
[tex]pH = pKa +log(\frac{conjugate base}{weak acid} )\\1.5=3.5 +log(\frac{conjugate base}{weak acid} )\\-2.0=log(\frac{conjugate base}{weak acid} )\\10^{-2.0} =\frac{conjugate base}{weak acid}\\\frac{conjugate base}{weak acid}=0.01=\frac{1}{100}[/tex]
When aspirin is absorbed more readily the ratio of conjugate base to acid is 1 to 100, being the acid the predominant form.
