Pelfrey 1!
Osmosis and Eggs: The Movement of Water To Effect Egg Size
Rachel Pelfrey
Alyssa Hall and Sarah Thomas
November 16, 2015
Pelfrey 2!
Introduction:
The movement of water from an area of low solute concentration to an area of high solute
concentration across a semi-permeable membrane is defined as Osmosis. This process is most
relatable to the cells within the bodies of living organisms which consistently carry out this
process. There are three solution results of Osmosis: Hypertonic, in which the solute
concentration outside of a cell is higher than the concentration within the cell, which provokes
the water within the cell to relocate to the outside of the cell, causing the cell to shrink and
shrivel; Hypotonic, in which the solute concentration is higher on the inside of the cell than the
concentration on the outside of the cell, triggering the movement of water into the cell from the
outside, which causes the egg to expand in size, possibly even to the point of bursting; and
Isotonic, in which the solute concentrations inside and outside the cell are equivalent, which
doesn’t provide any change in the movement of water into and out of the cell. Even thought this
process occurs at a microscopic, it can be seen without the use of a microscope and at a much
larger scale. Osmosis can be seen through the use of eggs. With the proper materials, the solution
effects of Osmosis can be seen over the course of seventy-two hours. In order to see the effects
of Osmosis, the beginning weights of the eggs used for each solution will be used for comparison
to the final weights after the solutions have had time to set in. In the experiment, the beginning
weight of the eggs will be the control, the solute concentration will be the independent variable,
and the final weight of the eggs will be the dependent variable. If the solute concentration is
higher in the liquid surrounding the egg than on the inside of the egg, then the egg will show the
results of a hypertonic solution and shrink, or, if the egg has a higher solute concentration than
the liquid surrounding it, then the egg will show the results of a hypotonic solution and expand.
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Materials:
1. Camera (can be handheld, computer, phone, etc.)
2. Permanent marker
3. Object to take notes with (can be digital [computer, phone, tablet, etc.] or pencil and paper)
4. Two standard plastic cups, transparent
5. Vinegar
6. Standard white chicken eggs
7. Scale (one the measures in grams)
8. Distilled water
9. Tap water
10. Iodized sea salt
11. Microwave
12. Spoon (metal or plastic)
13. Regular coffee mug
14. Liquid measuring cup (measures up to once cup)
15. Dry measuring cup (1/4 of a cup)
16. Calculator (can be handheld, phone, computer, etc.)
Procedure:
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1. Using a permanent marker, label the cups that will contain the eggs of the experiment, one
cup should be labeled Hypotonic and the other should be labeled Hypertonic
2. Soak the eggs in vinegar, make sure that the eggs are completely submerged, leave it to soak
overnight (eggs should soak for at least twenty-four hours) this will deteriorate the eggshell,
leaving an exposed membrane which will allow Osmosis to take place
3. After eggs have soaked, remove the vinegar from the cup, draining it carefully, and clean
eggs off with cold tap water, be sure to handle the eggs with care to prevent breaking
4. Return the eggs to cups, refill with vinegar, covering eggs completely
5. Repeat steps two and three (eggshells should be completely deteriorated by this time)
6. Return eggs to cups and weigh the eggs separately, record the weight in grams (take note and
take a picture), these are the control weights to compare the dependent end weights to
Pelfrey 5!
7. After the weights are recorded and pictures are taken, fill the Hypotonic cup with distilled
water, enough to cover the entire egg (if egg floats, tape an object onto the cup that will
submerge it)
8. Using the liquid measuring cup, measure out 2/4 cup of water and transfer to coffee mug,
heat for one minute thirty seconds in the microwave
Pelfrey 6!
9. While water is in the microwave, use the dry measuring cup to measure out 1/4 cup of
iodized sea salt
10. Once water is heated, pour salt into the water (may be boiling), and stir in with spoon until
dissolved
11. After salt is dissolved, let water cool before returning to cup to prevent distorting the plastic
and boiling the egg
Pelfrey 7!
12. Once water cools, return the solution to cup and carefully add in the egg, this is the
Hypertonic solution (if egg floats, tape an object onto the cup that will submerge it)
13. Set both of the cups aside and allow them to sit overnight (should sit for at least twenty-four
hours)
14. After eggs have sat in the solutions for the extended time period, remove the solutions and
rinse both the eggs and the cups, handle with care to prevent breaking (if egg breaks, return
to cup and record break in experiment notes)
15. Return eggs to cups, record observations of egg size change in both solutions, take pictures
for comparison to beginning eggs
16. Weigh the end result of the eggs, record the weight (in grams) in experiment notes and take
pictures
Pelfrey 8!
17. Once weights are recorded, subtract the larger weight from the smaller weight then divide by
starting weight for the Hypotonic egg (in this case, subtract the beginning weight from the
end weight then divide the difference by the beginning weight) then move the decimal place
over twice to calculate the percentage
18. Once the Hypotonic difference has been recorded, subtract the larger weight from the smaller
weight then divide by starting weight for the Hypertonic egg (in this case, subtract the end
weight from the beginning weight then divide the difference by the beginning weight) then
move the decimal place over twice to calculate the percentage
19. After the percent of change is calculated, record the data for each egg in experiment notes,
then discard of the eggs upon the completion of the experiment
Data and Results:
The eggs started as approximately the size of a hand palm, coated with a frail, yet hard
white outer shell with an almost ceramic or chalk-like texture. When placed in the vinegar, the
eggs appeared to have small bubbles rising from their shells, but showed no immediate change.
Over the course of the forty-eight hours in which the eggs sat in the vinegar, the eggshell slowly
deteriorated into a bubbly or foamy white essence along the surface of the vinegar, exposing a
thin, rubber-like membrane that exposed the nearly see through, cloudy egg albumen and the
yellow egg yolk. The eggs remained relatively the same in shape, but became more flexible and
less defined without the presence of the outer shell. The egg dedicated to the Hypotonic solution
had a beginning weight of ninety-four grams and the egg dedicated to the Hypertonic egg had a
beginning weight of ninety grams. When the distilled water was poured over the egg for the
Pelfrey 9!
Hypotonic solution, there was no evident change, not even bubbles were seen coming from the
egg. The tap water that was used for the Hypertonic solution did show change after being heated,
it was steaming and also bubbling, the salt dissolved almost immediately after it was added into
the water and not much stirring was needed to dissolve as much salt as possible. When the salt
was added, there was a loud hissing or sizzling sound followed by a thin puff of smoke or steam
which disappeared quickly. The solution was too hot when added back into the cup and distorted
it, the solution was then set in the freezer to cool until it was able to be added back into a new
cup equivalent to the previous one that became distorted. When the egg was added into the
Hypertonic solution, it appeared to float and had to be taped down, though there was no
immediate change in appearance. After another twenty-four hour lapse, the eggs showed a drastic
change in both color and size. The egg placed in the Hypotonic solution grew with a ten percent
rate of change and a final weight of 107 grams while the egg placed in the Hypertonic solution
had a forty percent rate of change with a final weight of fifty-two grams. The Hypotonic egg
seemed to be more of a clouded yellow in color with slight transparency and a hint of white
while the Hypertonic egg appeared to be mainly white with a separated yellow yolk, apparently
having been cooked by the boiling water, which allowed it to be easily salvaged and retrieved
after being dropped, triggering the separation of the egg albumen and yolk.
Solution
Hypertonic
Hypotonic
Beginning Weight (Grams)
90
94
End Weight (Grams)
52
107
Difference
38
13
40%
10%
Percent of Change
110
Beginnign Weight (Grams)
End Weight (Grams)
Pelfrey 1! 0
82.5
55
27.5
0
Hypertonic Egg
Hypotonic Egg
Conclusion:
The data collected throughout this experiment proves both hypotheses statements correct.
The ten percent rate of change that enlarged the egg in size that was placed in the Hypotonic
solution and the increased weight of thirteen grams proves that if the egg has a higher solute
concentration than the liquid surrounding it, then the egg will show the results of a Hypotonic
solution and expand. The forty percent rate of change that decreased the egg in size that was
placed in the Hypertonic solution as well as the decreased weight of thirty-eight grams proves
that if the solute concentration is higher in the liquid surrounding the egg than on the inside of
the egg, then the egg will show the results of a hypertonic solution and shrink. This experiment
revealed that the effects of Osmosis can be viewed at a scale that isn’t microscopic and also
reveals how easily identifiable the resulting solutions are. This experiment also pertains to real or
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everyday life because Osmosis is a process that is carried out by the individual cells of every
living organism on a daily basis and, therefore, needs to be understood at least at a basic level.
Along with this, the effects of Osmosis shown with the use of the eggs is identical to that of the
cells of living organisms.
Discussion:
The results of this lab are believed to be accurate due to the support from the data
collected throughout the experiment and its correspondence to the facts that go along with the
information used as the basis of this experiment. Such as, the way the data for the Hypotonic
solution matching with the definition of a Hypotonic solution and the way the data for the
Hypertonic solution matches with the definition of a Hypertonic solution. The lab would be
improved with better materials, more time, more careful and accurate planning, and much more
precision, which would allow the experiment to show the effects of Osmosis better than the four
day experiment done here. The information gathered from this lab can be applied to further any
previous knowledge of Osmosis and also to support it, along with this, it can be applied as a
teaching method to share with others learning about Osmosis starting from the basics. After
completing this experiment, there are no further questions of inquiries to follow the procedure,
data, or results that were collected.
Resources:
"Science of Eggs: Experiment With Naked Eggs Activity | Exploratorium." Exploratorium: The
Museum of Science, Art and Human Perception. Web. 9 Nov. 2015.