The Liquid-Liquid Shell Game

In the classic shell game, an object is placed under one of three shells and the shells are skillfully manipulated until it is not clear to anyone but the instigator under which shell the object resides. In the liquid-liquid shell game a mixture of two compounds is dissolved in ether and extracted with three different aqueous solvents (1M HCl, 1M NaHCO3, and 1M NaOH). At the end of the extractions it is not obvious what has happened to the two compounds since the experimenter ends up with four clear solutions. Some colors may arise during the liquid-liquid extraction process and gas is evolved when two immiscible solutions are first mixed, but these phenomena may not really indicate what has happened with the original compounds. The moment of truth for the aqueous solutions is when they are neutralized. A precipitate forms in one or two of the solutions are they are neutralized, which is pretty dramatic. The contents of the ether solution are only revealed after the ether has been evaporated. We leave the ether solution out in an uncovered beaker to evaporate over the space of a day or two. It is up to the student to make the connection between the (acid-base) chemistry and the observable results. The fact that the results are somewhat delayed may obscure this connection somewhat. Possibility, it would be better to neutralize each aqueous extract as soon as it is extracted. The ether could be evaporated with forced air in 10 to 15 minutes to make the results more immediately evident.

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