Question 1: PART A: A sample of Excedrin, the otc pain reliever, consists of thr

Question

Question 1:

PART A: A sample of Excedrin, the otc pain reliever, consists of three compounds; Aspirin, Acetaminophen, and Caffeine. If this mixture is dissolved in ether (organic solvent) and added to a separatory followed by the addition of an aqueous basic solution, what would be the substance on the bottom layer in the separatory funnel? (choose from answers below).

PART B: A sample of Excedrin, the otc pain reliever, consists of three compounds; Aspirin, Acetaminophen, and Caffeine. The mixture is dissolved in ether (organic solvent) and added to a separatory followed by the addition of 1 molar Dipotassium phosphate aqueous solution. If the aqueous solution is removed, what compound would not be in this aqueous solution. (choose from answers below)

PART C: It is ideal for the compound of interest to have an Rf of 0.5 on the TLC plate. If you compound shows an Rf of 0.1, what should you do. (Using Si-O coated TLC Plates). (Choose from answers below).

Explanation / Answer

Part A : -

Of course the bottom layer is of aqueous basic solution. Because the density of water is always greater than the ether.

Part B : -

The potassium salt of acetaminophen would not be in the aqueous solution. Because the potassium salt of acetaminophen is water insoluble and the potassium salt of acetyl salicylic acid i. e. aspirin can be water soluble.

Part C : -

In normal phase chromatography, where non-polar solvents such as hexane or pentane are used, non-polar compounds will move up the plate while most polar compounds will stay on the baseline. Inversely, polar solvents will allow polar compounds to move off the origin. Therefore you should Increase the amount of polar solvent in the mobile phase in relationship to the non-polar solvent.

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