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What makes for an effective liquid-liquid extraction?

What makes for an effective liquid-liquid extraction?. The added solvent must be more volatile than the desired component. It must also specifically dissolve the desired component. The component must have a greater tendency to dissolve in the added solvent than in the solution.

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What makes for an effective liquid-liquid extraction?

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  1. What makes for an effective liquid-liquid extraction? • The added solvent must be more volatile than the desired component. • It must also specifically dissolve the desired component. • The component must have a greater tendency to dissolve in the added solvent than in the solution. KD= CO = SO= CH20 SH20 Ratio of concentration = Ratio of solubility

  2. A substance X can be isolated from its plant source by solvent extraction. However, a minor component Y has an appreciable solubility in the solvents that may be used. Given below are the solubilities of X and Y in different solvents:

  3. Answers to Questions • Which is the best extracting solvent? CCl4 is the best extracting solvent it dissolves only a little amount of Y relative to the X component needed. It also dissolves the greatest amount of X among the choices. It is immiscible with water, which happens to be the solvent in the solution.

  4. Answers to Questions • Mathematically speaking, the choice relies on the KD and the best result is the one with the highest KD. The KD values with respect to water as calculated are the following: • From this table, it is evident that CCl4 is the yields the highest ratio, ergo the best possible choice as the extracting solvent.

  5. Answers to Questions • Given a saturated aqueous solution of X and Y and using 100mL of solvent in (1), determine the percent recovery of X in a single extraction. KD = SCCl4 = 8.75g/100g = 4.375 SH20 2.00g/100g KD = CCCl4 = Xg/100ml = 4.375 CH20 (2.00g-Xg)/100ml X = 1.63g %rec = Xpure x 100% = 1.63g x 100% = 81.4% Ximpure 2.00g

  6. Answers to Questions • Repeat (b) using 50mL of solvent in each of the two successive extractions. Determine the percent recovery and compare this with (b). KD = SCCl4 = 8.75g/100g = 4.375 SH20 2.00g/100g First extraction: KD = CCCl4 = Xg/50ml = 4.375 CH20 (2.00g-Xg)/100ml X = 1.37g

  7. Answers to Questions Second extraction: KD = CCCl4 = Xg/50ml = 4.375 CH20 (0.63g-Xg)/100ml X = 0.43g %rec = Xpure x 100%= (1.37+0.43)g x 100%= 90.0% Ximpure 2.00g In the double extraction, the percent recovery is comparably higher, considering the same amount of the solvent added.

  8. Answers to Questions • What is the percent recovery of the minor component in a single extraction using 100mL of the solvent in (a)? KD = SCCl4 = 1.25g/100g = 1.25 SH20 1.00g/100g KD = CCCl4 = Yg/100g = 1.25 CH20 (1.00g-Yg)/100g Y = 0.56 %rec = Ypure x 100% = 0.56g x 100% = 56% Yimpure 1.00g

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