By Sara Thompson
Special to the Enterprise
During spring and summer, trees use their leaves to produce energy and nutrients for the tree from sunlight through a process called photosynthesis. Photosynthesis could not work without chlorophyll, which gives leaves their green color. As the weather begins to cool off and winter approaches, the chlorophyll begins to break down in the leaf allowing other pigments to show through. When you mix crushed up leaves in a solution you can separate out their colors in this chromatography experiment at home.
What you will need: Leaves of different color, mortar and pestle or a bowl and spoon, a glass jar or cup for each color, rubbing alcohol, large baking dish, boiling water, and white coffee filters.
For the experiment gather leaves and sort them into different colors. Using a mortar and pestle or a bowl and spoon, crush up the leaves. Tearing them up a bit first can help, just try to keep the colors separated. When the leaves are crushed up a bit, place them in the bottom of a glass jar or cup. Do this to each color leaves, placing the different colors into different jars. Carefully pour enough rubbing alcohol into the jars to just cover the leaves, should only be a couple of tablespoons. You can choose to let the experiment sit overnight, or to speed up the process you’ll need to heat the glass jars. Place the jars into a baking dish and carefully pour boiling water around the jars. Do not put the water into the jars, but around them to heat them up. Wait about a half an hour and allow the pigments to seep into the rubbing alcohol. Next, cut the white coffee filters into strips. Place one end of the strip into the rubbing alcohol and allow the other end to hang over the edge of the baking dish, try to avoid the hot water. You will need to leave the strips in for an hour or two to allow the pigments to soak into the filter paper.
After a couple of hours take the filter paper out of the jars. The pigments from the leaves were released into the rubbing alcohol when they got warm. The rubbing alcohol is soaked up by the filter paper and brings the leaf pigments with it. The colors separate into bands on the paper and you are left with a beautiful display of colors on the filter paper.
This experiment is best done in the autumn while the leaves are changing color. The brightly colored pigments are only present when the green chlorophyll is breaking down at the end of summer, while the tree prepares for winter. This is a fun and colorful experiment that can be done with scientists of all ages, as long as the smallest explorers have an adult’s help with the leaf crushing and pouring of liquids.
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