Wednesday, October 20, 2010

Lab: Separation of a Mixture by Paper Chromatography





In this lab, we learned how to use paper chromatography to separate different components of a mixture.

The mixture we used was food coloring.


[Procedure Flowchart]

Part One
l        Prepare three large test tubes and place them in three Erlenmeyer flasks. Label the test tubes A, B, and C.
l        Cut a 66cm chromatography paper into three (each 22 cm). Use a pencil to draw a lien across each strip 4 cm from one end. Cut this end into a point.
l        Place 2 cm deep water in each test tube.

Part Two
l        Use a glass stirring rod and spot the strip of paper with the color assigned. (The spot should be smaller than 0.5 cm in diameter)
l        Insert the strip in test tube A. Observe what happens to the sample spot as the water slowly moves up.
l        Identify the solute front and solvent front. After about 20 minutes, when no further separation of color will occur, remove the stripe. Immediately draw a pencil line across the top edge of the solvent front before it disappears.
l        Measure d1 and d2, record in Tables 1 and 2. Calculate the Rf value and record it as well.
l        Clean up.

Part Three
l        Take the second strip of paper and spot it with a sample of green food coloring. Spot the third strip with a sample of the unknown mixture of food colorings. Label them at the top.
l        Insert the strips in test tubes B and C. Follow the same procedures as in Part Two.
l        Record data in Table 3
l        Clean up.









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