Compare to your prelab activity: The distribution coefficient, k for a compound

Question

Compare to your prelab activity: The distribution coefficient, k for a compound "A" between hexane and water is 7.5. What weight of A would be removed from a solution of 10 g of A in 100 mL of water by a single 50 mL extraction with hexane? Imagine you then take your aqueous layer and extract it a second time with fresh 50 mL of hexane. From the two 50 mL extractions how much would you recover? What is the difference between 2 Times 50 mL extractions and 1 Times 100 mL extracion and which one is more efficient?

Explanation / Answer

Two time extraction is always preferred over single extraction.

10 gm of compound extracted partitioned between water and hexane. Its difficult to predict how much is extracted in hexane, but roughly in first extraction around 0-80 % compound will be extracted, again depend on nature of chemical like polarity, solubility.

2 x 50 ml is preferred and efficient over 1 x 100 ml. Because all compound might not be extracted in in single extraction and small quantity always remains in aqueous, so to ensure complete extraction, multiple extraction is always better,.

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