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CC 2. Answer (all) parts (a) - (b). a) Prior to chromatographic determination, residue estrone in wastewater can be preconcentrated by extracting with ethyl acetate. (1) Considering the partial dissociation of estrone in the aqueous layer, derive the following equation for the distribution ratio (D) which represents the partition of estrone between water and ethyl acetate. (Assume no dissociation or dimerization in the organic layer. All terms have their usual symbols) Kp[H+ (aq) D = [H+ (aq) + K. (20 Marks) vag (ii) Calculate the percent extraction efficiency if a 30 mL sample of estrone contaminated wastewater was buffered at pH = 4 and extracted with a 10 ml 0.9 portion of ethyl acetate. (For estrone, pka = 10.8; Kp = 4.1) 1 (All terms have their usual symbols) 1 + Hint: 9. = D Vorg Viac (10 Marks) (iii) How many extractions are needed to achieve a final extraction yield of 99.9%? log (1 - E.) Hint:n (All terms have their usual symbols) log (1 - E) (10 Marks) (iv) The variation of distribution ratio of estrone as a function of pH is reported as follows. Briefly explain this behavior, without any calculations.. pH 2 4 6 8 10 12 14 D 4.2 4.1 4.1 3.6 1.2 1.1 0.2 (10 Marks)