MadSci Network: General Biology
Query:

Re: Please could you help me. I would like to carry out an experiment to show

Date: Fri Apr 21 16:22:56 2000
Posted By: Erin Cram, Grad student, Molecular and Cellular Biology, University of CA, Berkeley
Area of science: General Biology
ID: 955654731.Gb
Message:

These project ideas are from : http://www.sciencemadesimple.com/leaves.html
Many other ideas are available via the internet.  Try "color leaves experiment" 
as a key word search at http://www.google.com


PROJECT 1 - Separate Colors in a Green Leaf using Chromatography

What you need: 

     leaves, small jars (baby food jars work well) 
     covers for jars or aluminum foil or plastic wrap 
     rubbing alcohol, paper coffee filters 
     shallow pan, hot tap water, tape, pen 
     plastic knife or spoon, clock or timer. 

What you do: 

   1.Collect 2-3 large leaves from several different trees. Tear or chop the 
leaves into very small pieces and put them into small jars
     labeled with the name or location of the tree. 
   2.Add enough rubbing alcohol to each jar to cover the leaves. Using a plastic 
knife or spoon, carefully chop and grind the leaves in the
     alcohol.
     SAFETY NOTE: Isopropyl rubbing alcohol can be harmful if mishandled or 
misused. Read and carefully follow all warnings on the
     alcohol bottle. 
   3.Cover the jars very loosely with lids or plastic wrap or aluminum foil. 
Place the jars carefully into a shallow tray containing 1 inch of
     hot tap water.
     SAFETY NOTE: Hot water above 150 F can quickly cause severe burns. Experts 
recommend setting your water heater thermostat
     no higher than 125 F. 
   4.Keep the jars in the water for at least a half-hour, longer if needed, until 
the alcohol has become colored (the darker the better). Twirl
     each jar gently about every five minutes. Replace the hot water if it cools 
off. 
   5.Cut a long thin strip of coffee filter paper for each of the jars and label 
it. 
   6.Remove jars from water and uncover. Place a strip of filter paper into each 
jar so that one end is in the alcohol. Bend the other end
     over the top of the jar and secure it with tape. 
   7.The alcohol will travel up the paper, bringing the colors with it. After 30-
90 minutes (or longer), the colors will travel different
     distances up the paper as the alcohol evaporates. You should be able to see 
different shades of green, and possibly some yellow, orange
     or red, depending on the type of leaf. 
   8.Remove the strips of paper, let them dry and then tape them to a piece of 
plain paper. Save them for the next project. 



PROJECT 2 - Separate Colors in a Fall Leaf using Chromatography

What you need: same as Project 1.

What you do: 

   1.Repeat step (1)-(8) from Project 1, this time using leaves that have changed 
color. You may have to wait much longer in steps (4) and
     (7). There is normally much less of the other colors in the leaves compared 
to the green chlorophyll. 



PROJECT 3 - Observe how light affects color development 

What you need: 

     a tree with leaves that turn red in autumn 
     aluminum foil or heavy paper and masking tape. 

What you do: 

   1.Before the leaves turn colors in the fall, find a maple tree, flowering 
dogwood, sweet gum, or other tree or shrub that you know will
     turn bright red or purple. 
   2.Find several leaves that receive bright sunlight, and cover part of them 
with foil or heavy paper and tape. 
   3.After the leaves have changed color, remove the covering and observe the 
different colors underneath. These are the colors that were
     in the leaf all summer. The bright reds and purples are only made in the 
fall, with exposure to light. 



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