Name:______________________ Date:____________ Block:___________
Mini-Lab: Chromatography of Green Leaves
Green is the color you notice most about plants. The principal
pigment in green plants is chlorophyll. These pigments help plants to
gather the sun’s energy. Without chlorophyll, plants could not make food.
The colored substances in the leaves, known as pigments, can be separated
by paper chromatography.
ChromatographyExperimental Question: Why do green leaves change their colors in
autumn?
Hypothesis:
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Materials: (per lab group)
250 ml beaker or jar
25 ml graduated cylinder
mortar and pestle
scissors
goggles
10 ml chromatography solvent
paper chromatography strips
samples of green leaves
Procedure:
1. Put your goggles on to ensure that your eyes are protected throughout the
duration of this lab. Remember… the goggle police are watching!
2. Choose a few leaves from the samples that your group members brought
in. From what plant did the leaves come from?
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3. Tear the leaves into small pieces (about the size of a postage stamp).
Place the pieces in a mortar. Grind them to a paste with the pestle, using
a circular motion as pictured in the diagram below.
4. Add 10 ml of acetone. Continue grinding until the liquid is deep green in
color. Group members should take turns grinding.
5. Pour the green pigment solution into a 250 ml beaker.
6. Obtain a strip of chromatography paper, one for each group member.
Caution: Be sure to only hold the strips of chromatography paper on
the edges, as oils from your fingers could affect results.
7. Take one end of the chromatography paper strip and make a fold about
one inch from the end. Write your initials on this fold. This fold will
help anchor your strip.
8. Place the other end of the chromatography strip into the green solution
and place the fold you made in step 7 over the edge of the beaker.
9. Watch the colored rings from in the filter paper for about 10-15 minutes.
a. What color appears first? ___________________________________
b. How many rings of this color are there? ________________________
c. What color appears next? ___________________________________
d. How many rings of this color are there? ________________________
10.Wash the mortar and pestle thoroughly. Make sure to wash and return
materials to the materials table.
11.Glue your chromatography strip to your lab report under the analysis
section.
Analysis Questions: (To be done in complete sentences!)
1. Describe the appearance of the chromatography strip at the conclusion of
the experiment.
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2. a. Is chlorophyll composed of one or several pigments?
b. What proof do you have?
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3. Examine your chromatography strip. Each color band is a different
pigment. Listed in order from top to bottom on an ideal chromatogram
are…
Carotene- orange in color
Xanthophyll- yellow in color
Chlorophyll a- bright green in color
Chlorophyll b- a dull or khaki green color
What pigments can you see on your chromatogram?
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4. Many leaves change color in the fall. Propose a hypothesis for how it is
possible for this color change to happen based on your new knowledge of
pigments present in chloroplasts.
(Hint- Chlorophyll a and b are easily broken down by the cooler
autumn temperatures).
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Glue your chromatogram here….