If the pH was not lowered in step B of the above process and instead remained at ~6,identify which (if any) of the components would be in a different layer of the extraction mixture.Justify your answer in 12 sentences
The correct answer and explanation is:
To accurately answer this question, we need to understand what occurs during a typical acid-base extraction process and what “step B” refers to—commonly a step involving pH adjustment to separate organic compounds based on their acidity or basicity. Let’s assume step B is designed to protonate or deprotonate a compound to make it either water-soluble (ionic) or insoluble (neutral), which determines its layer placement (aqueous or organic).
Correct Answer:
If the pH was not lowered in step B and instead remained at ~6, then acidic components such as carboxylic acids may not be fully protonated, and thus may remain ionized and soluble in the aqueous layer instead of precipitating or moving into the organic layer. Therefore, a component like benzoic acid, which would normally become neutral at low pH (around 2), might stay in the aqueous layer if the pH stays at 6. This would change its position in the extraction mixture.
Explanation (approx. 300 words in 12 sentences):
In acid-base extraction, the separation of compounds depends on their solubility in either aqueous or organic solvents, which is controlled by adjusting the pH. Step B typically involves lowering the pH to around 2 to protonate acidic compounds like carboxylates, making them neutral and less soluble in water. At pH 6, carboxylic acids (like benzoic acid) exist predominantly in their deprotonated, ionic form (carboxylate anion), which is highly water-soluble. As a result, such a compound would remain in the aqueous layer rather than moving to the organic layer.
This shift affects the effectiveness of separation. Normally, after acidification in step B, the neutralized acid becomes less polar and thus migrates into the organic layer. If the pH is not lowered, the acid remains charged and does not extract efficiently into the organic solvent. Basic compounds such as amines would remain unaffected at pH 6, as they require a basic environment to become deprotonated and organic-soluble.
Therefore, the component affected by the pH not being lowered is the acidic one—specifically carboxylic acids. This incomplete protonation would compromise their removal from the aqueous layer. Consequently, purification or recovery would be inefficient. No new layers form, but the distribution of solutes between the layers would be altered. Only the acidic compound would be in the wrong layer. Hence, careful pH control is essential for proper extraction efficiency.