Exp5 Flashcards
(17 cards)
What determines the distribution of solutes in a mixture?
The various solutes distribute themselves between the organic and aqueous phases according to their relative solubility in each solvent.
What is the distribution coefficient (KD)?
At equilibrium, the ratio of the concentration or solubility of the substance in the organic phase to that in the aqueous phase is called the distribution coefficient (KD).
How is KD calculated?
KD = concentration of substance in organic / concentration of substance in water.
What are the variables used in the KD formula?
C0 = concentration of organic solution, Cw = concentration of aqueous solution, So = solubility in organic layer, Saq = solubility in aqueous layer.
What do Vo and Vag represent?
Vo = volume of organic solution, Vag = volume of aqueous solution.
What do Wo and Wag represent?
Wo and Wag are the weights in grams of material dissolved in each phase.
What is the formula for calculating KD?
KD = (12g/100ml) / (6g/100ml)
KD is the distribution coefficient, indicating how a compound distributes between two solvents.
If a solution of 6g of A in 100ml of water is shaken with 100ml of ether, what is the value of X?
X = 4g of A in the ether layer
This calculation is based on the equilibrium established by KD.
What amount of A is left in the water layer after extraction with ether?
2g left in the water layer
How does the efficiency of extraction change when using two 50ml portions of ether instead of one 100ml portion?
Two extractions with 50ml portions extract 4.5g of A, while one extraction with 100ml extracts only 4g of A
This demonstrates the principle of multiple extractions being more efficient.
What is the amount of A in the ether layer after the first extraction with 50ml?
3g in the ether layer
What is the amount of A left in the water layer after the first extraction with 50ml?
3g in the water layer
What is the amount of A in the ether layer after the second extraction with 50ml?
1.5g in the ether layer
What is the amount of A left in the water layer after the second extraction with 50ml?
1.5g in the water layer
What is the percentage of extraction for the extraction with 100ml ether?
% E = (4/6) * 100 = 66.6%
What is the percentage of extraction for the double extraction with 50ml portions?
% E = (4.5/6) * 100 = 75%
True or False: Several small-scale extractions are less effective than one large-scale extraction.
False
