Separatory Funnel |
1. | The aqueous iodine solution (the solution to be extracted) is placed in the sep funnel (held in ringstand) and a small amount of dichloromethane poured into a beaker.
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2. | A portion of the dichloromethane is added to the sep funnel and the funnel shaken gently. To shake the funnel, invert it while holding the stopcock in with your hand. When volatile solvents are being used the sep funnel needs to be vented occasionally. Do this by pointing the inverted funnel away from yourself and others and opening the stopcock.
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3. | Return the sep funnel to the ringstand and allow the layers to separate. Because most of the iodine has been extracted into the dichloromethane, the aqueous layer becomes lighter brown. The iodine in the dichloromethane layer makes it appear purplish.
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4. | Remove the stopper and drain the lower layer (the dichloromethane layer in this case) through the stopcock into a beaker or flask. The upper layer should remain in the sep funnel.
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5. | To extract additional iodine, steps 2 - 4 can be repeated by adding a second portion of dichloromethane to the sep funnel containing the aqueous layer. Additional extractions can be performed until most of the iodine is removed from the aqueous layer. For a majority of situations this can be accomplished if three extractions are performed.
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6. | Combine the dichloromethane portions. The dichloromethane now contains almost all the iodine, while only a small amount of I2 remains in the aqueous layer. |