Using the Henderson-Hasselbalch equation, figure if someone accidently consumed the same concentration of the weak acid herbicide 2,4- dichlorophenoxyacetic acid, pK_a = 2.8, and the weak base herbicide atrazine, pK_a= 1.7, in the human intestinal pH of 6, which would be more absorbed on this factor alone.

Question

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The Answer is For weak acids pH = pK_a+log [ionized]/ [non-ionized], 6 = 2.8 + log [ionized]/ [non-ionized]

\rightarrow

6 - 2.8 = 3.2 = log [ionized]/ [non-ionized]

\rightarrow

10^3.2= [ionized]/ [non-ionized] = 1585 [ionized]/1 [non-ionized] where non-ionized is favored for absorption - so predicted little absorption.
For weak bases pH = pK_a+log [non-ionized]/ [ionized], 6 = 1.7 + log [non-ionized]/ [ionized]

\rightarrow

6 - 1.7 = 4.3 = log [non-ionized]/ [ionized]

\rightarrow

10^4.3= [non-ionized]/ [ionized] = 199953/1 [non-ionized]/[ionized], so highly favored for absorption of the non-ionized atrazine.

Using the Henderson-Hasselbalch Equation, Figure If Someone Accidently Consumed the Same