A weak organic acid (pKa = 4.82) is being studied as a potential broadleaf herbicide. One aspect of the study includes testing for its presence in water samples taken from a run-off of a field.
The acid has a distribution ratio of 62 between water and chloroform at a pH of 3.42.
a. Using 30.0 mL of chloroform, what fraction of the compound will be extracted from a 50.0 mL field sample at pH = 3.42?
b. What fraction of the acid in the 50.0 mL sample would be extracted, again at pH 3.42, using three 10.0 mL portions of chloroform?
c. If the pH of the solution was changed to 6.00, what fraction would be extracted using 30.0 mL of chloroform with a 50.0 mL field sample?
d. Qualitatively, predict what effect a lower pH would have on the extraction.