Separating Components of a Mixture by Extraction

Learn about extraction as a technique for separating mixtures based on physical properties like solubility and chemical properties like reactivity. Understand why particle size alone is insufficient for separating small molecules.

Demonstrate extraction of sodium chloride and cholesterol using water and ether. Add both solvents to the mixture, swirl, transfer to a separatory funnel, and observe the formation of two immiscible layers based on density differences.

Dissolve the three-component mixture in ether and transfer to a separatory funnel. Add aqueous hydrochloric acid to protonate and extract the basic 4-chloroaniline into the aqueous layer. Shake with venting, then drain and wash the aqueous layer multiple times.

Add aqueous sodium bicarbonate to the remaining ether layer to deprotonate and extract the acidic benzoic acid into the aqueous layer. Shake with venting, drain, and wash the aqueous layer multiple times to collect all benzoate.

Pour the remaining dibromobenzene solution from the top of the funnel into a new flask. Wash the funnel with ether and add sodium sulfate desiccant to remove trace water, then filter into a pre-weighed flask.

Gently heat the dibromobenzene solution on a hot plate at low setting to evaporate the volatile ether. Weigh the flask to determine the mass of recovered dibromobenzene solid.

Add sodium hydroxide to the aniline salt solution while cooling in a water bath to deprotonate and precipitate 4-chloroaniline. Verify completion by checking pH reaches 11-12, then collect the solid using a Buchner funnel with vacuum filtration.

Add hydrochloric acid to the benzoate salt solution to protonate and precipitate benzoic acid. Verify completion by checking pH reaches approximately 2, then collect the solid using a Buchner funnel with vacuum filtration to obtain the final separated components.