May '11
15
MCAT Question of the Day | MCAT Course


  • Q:

    During a purification experiment, Compound X is extracted from ethyl acetate in which it is readily soluble into an aqueous Solution A in which it is only moderately soluble. Compound X has a pKa of 2.8 and has a carboxylic acid as its primary functional group. In the next step, the student wants to precipitate Compound X and attempts different experimental conditions. The observations from two conditions are shown in the table below.

      Condition 1 Condition 2
    pH 6.5 0.5

    Assuming the there is no difference in the experimental conditions except for the pH, which of the following is true?


     

    A

    Condition 1 will precipitate Compound X because Compound X will be insoluble when the pH is above the pKa

    B

    Condition 2 will precipitate Compound X because Compound X will be insoluble when the pH is below the pKa

    C

    Condition 1 will precipitate Compound X because Compound X will be insoluble when the pH is below the pKa

    D

    Condition 2 will precipitate Compound X because Compound X will be insoluble when the pH is above the pKa




    Tags: Acid/Base Equilibria | Solutions | Carboxylic Acids | Suggest a tag
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