Lab Report – Chlorophyll’s
reaction to Light
Aim To investigate the
effect of chlorophyll on visible light.
I’m going to
investigate what is going to happen to visible light when it’s shown through
chlorophyll, which is the aim of this experiment. Chlorophyll is made in plants
during photosynthesis which is a process were plants take in CO2 and H20 and by
sunlight creates the by-products C6H12O6 and O2i,
also called glucose and oxygen. The chlorophyll appears greenii,
because when it comes to color we only see the reflected color that an object
is not absorbing when light hitsiii.
Therefore we will only see the reflected color green through the chlorophyll
because the chlorophyll reflects the color green and have absorbed all the
§ Hot plate
§ 2 Beakers
§ 1,5 dl Water
§ Thin leaf
§ Thick leaf
§ Stop watch
§ 2 tbsp. Acetone
§ A pinch of Sand
§ Small Funnel (with
a small hole)
Method – Part 1 Making solution of chlorophyll
Pour water into the beaker
and place the beaker on the hot plate.
Start the hot plate
and wait until the water is boiling.
Plunge both of the
leaves into the water.
Start the stopwatch
and after 1 min use the tweezer to take up the thin leaf and after 2 min do the
same to the thick leaf.
Put the leaves into
the mortar and grind them.
Add acetone and sand.
until you have a dark green liquid.
Place the funnel on
top the other beaker.
Filter the liquid by
pouring it through the funnel (all you shall be left with is liquid).
10. Pour the finished liquid into a cuvette and close
Method – Part 2 Discover the
effects of chlorophyll on sunlight
11. Turn on the projector and place the prism on top of
the platform to make the light beam go through it.
12. Adjust the prism so a rainbow will show onto a flat
surface were the light beam goes.
13. Hold the cuvette in front of the light beam.
14. Write down what happens to the light.
Here is a table
showing the results from all the main steps of the experiment. The final result
was that the beam of light became green of the chlorophyll.
For 1 min
For 2 min
Easy to grind
Difficult to grind
Green liquid formed
Green liquid formed
Small chunks are not dissolved
Green liquid solution
Green liquid solution
Light from projector
The result agreed to my hypothesis, the light appeared green. Why the
color green appeared is because chlorophyll can only absorb specific
wavelengths in our visible light spectrum. The prism broke up the white light
form the projector into the colors of the visible light spectrum, all colors
have different wavelengths. The wavelengths that chlorophyll can absorb are the
long and short wavelengths, which are the colors red and blue. The wavelength
left that was not absorbed by the chlorophyll was the wavelength that is green.
Therefore we only saw the color green because that was the color reflected and
not absorbed by the chlorophyll.
The group that I was in could have boiled the thick leaf longer differently
to make the end result of the experiment more credible. Because that would have
made it less solid and in that way easier to grind. Which would have left us
with a higher level of chlorophyll in our liquid. I do not believe we did any
mistakes in our trial of the experiment that changed the outcome in the end*. A
variable in this experiment can be that some people used leafs from different
plants. Which could have an effect on the results since different plants have
different amounts of chlorophyll, some may contain more and some less. In that
way can the concentration of chlorophyll change the end result by the light not
turning clear green.
A way to improve this lab could be to not use the thin leaf and use two
thick leaves instead. That would give us a liquid with a higher concentration
of chlorophyll. That makes the part where we place the chlorophyll in front of
the light beam sharper.
We could also develop this lab by comparing the liquid of a healthy leaf
with a leaf from the same plant that is the opposite. Since the opposite leaf
most certain have lower levels of chlorophyll because it no longer practice photosynthesis.
But we do not know that for certain and therefore it can be an experiment to
*Since we were not
supposed to mention that we added the alcohol together with the acetone and
sand. But if we were to mention that: We could also improve the experiment by
not using the alcohol because it made the liquid yellow. Which was not how the
experiment was thought to turn out, but we added acetone to make it green again
which saved the experiment. But for next time I would not use the alcohol at
all because it turned the liquid yellow and it wasted time to correct the