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Different Colored Leaves

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Different Colored Leaves (continued) 6. Rub the ribbed edge of a coin over the leaf to transfer the pigments onto the chromatography strip. Make sure you're rubbing the coin on top of the pencil line. 7. Repeat Step 6 eight to ten times with different portions of the leaf. 8. Remove the cap from your vial and carefully place the chromatography strip into the vial so the pointed end is barely immersed in the solvent. Make sure not to immerse the pigments in the solvent. a. Do this under a fume-hood or with proper ventilation 9. Cap the vial and leave it undisturbed. Observe as the solvent is drawn up the chromatography strip by capillary action. You'll be able to see the plant pigments separating along the strip. No¬tice the different colors you see during this process. 10. When the solvent is approximately 1 cm from the top of the strip, remove the cap from the vial. Using forceps, remove the strip from the vial. 11. Immediately mark the location of the solvent front with pencil. 12. Note the pigment colors you observe on the chromatogram. 13. Once the solvent has dried, mark the center of each color band on your chromatogram using pencil. 14. Use a metric ruler to find the distance from the original pencil line to the solvent front and the marks you made for each color band. 15. Calculate the Rf value for each pigment band by dividing the distance the color traveled by the distance the solvent traveled. Expected Results: Results may vary based on materials used, setup, procedure, and other factors, however, here are a few examples on what to expect: • Prior to the experiment, students should form a hypothesis regarding the pigments they would expect to see based on their leaf selection. • Results will vary greatly based on leaf types used. Follow-up/Teaching Notes: • When selecting leaves, find leaf types that have a higher water content. Dry leaves are very difficult to use in this kind of procedure. • This inquiry works best if different students have different leaves, so groups can compare their results. Add Inquiry: • Repeat the procedure using leaves from a deciduous tree at different stages of color change? Do the change as the color changes? Disposal/Clean-up: • Dispose of chemicals according to local regulations. Solvent Front A B C D + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com Find materials for this activity at wardsci.com. Discover more free activities at wardsworld.wardsci.com

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