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Unformatted text preview: ium carbonate- it prevents the extraction of tannin. It reacts with tannin and
forms an insoluble salt thus removing it from the solution
2. Sodium sulphate- It acts as drying agent because it removes any water that remains
in the chloroform layer.
B. Give at least three characteristics of chloroform that make it a good extracting solvent
Chloroform is a good extracting solvent fro the isolation of caffeine because
caffeine dissolves in it, it is immiscible with water and it has lower boiling point
C. How efficient is the extraction of tea leaves containing 1 g of caffeine with two 30-mL
portions of chloroform over that of a single step extraction (K25° C = 8.38)? D. What are emulsions? Why do they form during extractions? How are they minimized?
Emulsion is a mixture of two immiscible liquids. One liquid (the dispersed
phase) is dispersed in the other (continuous phase). When tannins are converted to their
salts, they become an ionic surfactant. These causes the materials that don¶t dissolve in water to form an emulsion with water. This emulsion can be minimized reducing the
energy input through slow and careful shaking and swirling of the separatory funnel.
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This document was uploaded on 03/03/2014.
- Fall '14