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Separate Colors In A Fall Leaf Using Chromatography
By Chris Yates, Fri Dec 9th
Fall is a beautiful time of year with all the leaves arechanging colors. Children wonder why it happens, so it's a greatopportunity to use the power of science to show them theseparate leaf colors and to explain how the leaves actuallychange colors. What you need: - Leaves that have changed color
- Small jar (baby food jars are the best) - Lid for the jar (aluminum foil or plastic wrap if you don'thave a lid) - Rubbing - Paper coffee filter - A shallow pan or tray - Hot water - Tape - A pen - Plastic knife or spoon - A timer What you do: NOTE: Adult supervision is required for this activity. Pleaseread all instructions completely before starting. Observe allsafety precautions. 1. Collect two or three fairly large leaves. Tear or chop themup and put them into a jar. 2. Add rubbing to the jar so that you completely coverthe chopped up leaves. Use the plastic knife or spoon to grindthe leaves into the and break them up. NOTE: Rubbing can be dangerous if mishandled or misused.Please read and follow all warnings on the rubbing alcoholbottle. 3. Loosely cover the jar with the lid (aluminum foil or plasticwrap). Fill the shallow pan with about an inch of hot water andcarefully place the jar into the pan. Gently swirl the jar everyfive minutes and replace the hot water as it cools off. 4. Leave the jar in the water for at least half an hour or untilthe becomes colored. The deeper the color of the alcoholthe better. 5. While you're waiting, cut a long strip of coffee filterpaper. When the jar is ready, remove it from the water anduncover it. Put the strip of coffee filter paper into the jar sothat one end is in the and the other end is outside thejar. Secure the dry end with a piece of tape to the outside ofthe jar. 6. The colored will travel up the paper. If you leavethe paper in the for about 90 minutes or so, each colorof chlorophyll (as well as other "color" chemicals) will travela
different distance up the paper as the evaporates. Youshould be able to see different shades of green, yellow, orange,red, etc, depending on the color and type of leaves you're using. 7. Remove the strip of paper and let it dry by taping it to aplain piece of paper. Why the Leaves Change Color During summer, the leaves of trees are factories producing sugarfrom carbon dioxide and water by the action of light onchlorophyll. Chlorophyll causes the leaves to appear green.Water and nutrients flow from the roots, through the branches,and into the leaves. The sugars produced by photosynthesis flowfrom the leaves to other parts of the tree, where some of thechemical energy is used for growth and some is stored. The shortening days and cool nights of autumn trigger changes inthe tree. One of these changes is the growth of a corky membranebetween the branch and the leaf stem. This membrane interfereswith the flow of nutrients into the leaf. Because the nutrientflow is interrupted, the production of chlorophyll in the leafdeclines, and the green color of the leaf fades. If the leaf contains carotene, as do the leaves of birch andhickory, it will change from green to bright yellow as thechlorophyll disappears. In some trees, as the concentration of sugar in the leafincreases, the sugar reacts to form anthocyanins. These pigmentscause the yellowing leaves to turn red. Red maples, red oaks,and sumac produce anthocyanins in abundance and display thebrightest reds and purples in the autumn landscape. The range and intensity of autumn colors is greatly influencedby the weather. Low temperatures destroy chlorophyll and promotethe formation of anthocyanins, if the nights stay abovefreezing. Bright sunshine also destroys chlorophyll and enhancesanthocyanin production. Dry weather, by increasing sugarconcentration in sap, also increases the amount of anthocyanin.So the brightest autumn colors are produced when dry, sunny daysare followed by cool, dry nights. -------------------- Chris Yates makes it EASY to craft withchildren of all ages with Hundreds of FREE craft projects andideas. Visit http://www.FreeKidCrafts.com Now! About the author:None
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