Chlorophyll Extraction
Authors: Brittland K. DeKorver, Kristen Anderson, Yune Leou-on, Mark Pan
Institute for Chemical Education and Nanoscale Science and Engineering Center
University of Wisconsin-Madison
Purpose: To learn about the fluorescence and the function of chlorophyll in
plant leaves.
Learning Objectives:
1. Chlorophyll is substance that is responsible for the green color of plant
leaves.
2. Chlorophyll uses sunlight to convert carbon dioxide and water into glucose
and oxygen.
Next Generation Science Standards (est. 2013):
 PS3.A: Definitions of Energy
 PS3.B: Conservation of Energy and Energy Transfer (partial)
 PS3.D: Energy in Chemical Processes and Everyday Life
 LS1.A: Structure and Function
 LS1.C: Organization for Matter and Energy Flow in Organisms
National Science Education Standards (valid 1996-2013):
 Standard B: Physical Science
o Transfer of Energy
 Standard C: Life Science
o Structure and function in living systems
Grade Level: 2-8
Time: 1 hour
Materials:
 Leaves (gathered from
outside; or purchased spinach
leaves)
 Onion Skin
 Elodea Leaf (an aquarium
plant)
 Isopropyl alcohol




Beaker
UV lamp or UV LED
flashlights
Hot plate
Secret ballot sheets (see
Evaluation section)
Safety:
Caution students that isopropyl alcohol is poisonous and should not be eaten.
Students should not shine UV lights at each other. Students should not be
permitted to use the UV lamp.
Introduction:
Many compounds in plants are useful to humans, whether for making a product
(such as rubber), giving health benefits (such as aspirin), or for decoration (such
as dyes). Often, these chemicals found in plants are identified and then adapted
to be more useful to us. The first step in this process is extracting the chemicals.
Today, the students will extract chlorophyll from plant leaves, and then confirm
the presence of chlorophyll by testing its fluorescence.
Fluorescence occurs when the electrons of a molecule absorb invisible light,
giving the electrons more energy. When this happens, the electrons are said to
be excited. Then, the electrons release the energy, returning to the original
ground state. The energy that is released is slightly less than was absorbed, so it
is no longer invisible, and a color is observed. Chlorophyll fluoresces a deep red
color under UV light.
Procedure:
1. Act-it-out
a. Assign two students to play the role of chlorophyll and sunlight.
Provide appropriate props (e.g. a cardboard sun, a green
robe/wrap). Introduce them as the sun and chlorophyll to the whole
group.
b. Provide chlorophyll with a sign designating “carbon dioxide + water”
on one side and “glucose + oxygen” on the other.
c. Tell the group that the sun provides light energy (GENTLY bumps
into) to the chlorophyll, and when the chlorophyll gets that energy, it
can change the carbon dioxide and water into glucose and oxygen.
d. Narrate that the plant uses the glucose and the oxygen is released
into the air.
e. Allow other students to model as the chlorophyll and sunlight, if
time permits.
f. Tell the students that in today’s lesson, they will be learning more
about chlorophyll.
2. Using Microscopes
a. Allow students to use microscopes to compare and contrast a layer
of onion skin with an Elodea leaf.
3. Chlorophyll Extraction (if time permits)
a. Heat some water in a beaker on a hotplate (or in a microwave)
b. Place the plant leaves in the hot water and wait for three minutes.
c. After removing from the water, dry the leaves on paper towel. Have
the students tear the plant leaves into small pieces and/or smash
them in a shallow dish. The smaller they are, the better the
extraction will be.
d. Allow the students to measure and pour 5mL of isopropyl alcohol
onto the leaves. Wait about 5 minutes, or until the isopropyl alcohol
turns green.
e. Filter or decant the solution into a vial.
f. Have the students verify the presence of chlorophyll in their vials by
testing its fluorescence. Chlorophyll will fluoresce red.
Discussion:
Have students describe what they saw under the microscope to the mentors and
to each other. They should notice that both have cell walls, but the Elodea cells
also contain green dots (chloroplasts). Tell the students that this is where the
chlorophyll is.
Tell the students that they will be breaking up the plants’ cell walls in order to
remove the chlorophyll from the chloroplasts, in the extension section.
Evaluation:
Provide “Secret Ballots” for the students. On one side, it will read “Will you be
able to see chlorophyll in an Elodea leaf or in the onion skin?” Students will write
their prediction before the lesson and fold the ballot in half. On the other side, it
will read, “Which one had chlorophyll, an Elodea leaf or the onion skin?”
Students will complete this before they leave to earn a candy reward. Emphasize
to the students that it is ok if their prediction is different than their final answer.
This lesson is the product of the Institute for Chemical Education and the
Nanoscale Science and Engineering Center at the University of Wisconsin-Madison.
This Material is based upon work supported by the National
Science Foundation under grant number DMR-0425880.
SCIENCountErs Lessons are licensed under a Creative Commons AttributionNonCommercial 4.0 International License. Permissions beyond the scope of this license may
be available by emailing [email protected].