Name ________________
Period:________________
Egg Lab
Selectively Permeable Membranes
Purpose: The purpose of this lab is to investigate the properties of a
selective permeable membrane.
Materials:
Two
250 ml beakers, corn syrup, vinegar, balance, paper towels, eggs, plastic wrap,
water.
Procedure:
Day
1: Weigh
and determine the volume (by water displacement) of two eggs. Use a calculator to determine their
densities (mass divided by volume. Label two 250 ml beakers with the initials
of everyone in your lab group. Label
one of the beakers “Egg 1” and the other “Egg 2”. Place one egg into each beaker. Cover each egg with vinegar (3%
acetic acid). Continue filling the beakers
until the level of the vinegar is about a half inch above the top of the
eggs. Make observations about the
appearance of the eggs. Then cover the
beakers with cling wrap and set them aside as directed by your teacher.
Day
2: Remove the cling wrap from the beaker. Flood the beakers with water to remove the
vinegar. Carefully remove the eggs from
the beakers and gently rinse them off.
Place them each on a piece of paper towel, keeping track of which is egg
1 and which is egg2. Record your
observations. Weigh and determine the
volume of each egg again. Calculate their
densities. Rinse out the two beakers
and put the eggs back in (keeping track which is which). Carefully fill the beaker labeled “Egg 1”
with tap water to a half inch above the egg.
Carefully fill the beaker labeled “Egg 2” with corn syrup to a half inch
above the egg. Then cover the beakers
with cling wrap and set them aside as directed by your teacher.
Day
3: Remove the cling wrap. Remove Egg 1 and put
it on a paper towel. Carefully flood the beaker labeled “Egg 2” to rinse off
the corn syrup. Record your
observations of the two eggs. Weigh and
determine the volumes of each egg again.
Calculate their densities.
Discard the eggs and clean up as directed by your teacher.
Data:
Day
1: Raw, unspoiled eggs, straight from the refrigerator.
|
|
Mass
(grams) |
Volume
(ml) |
Density
(g/ml) |
|
Egg
1 |
|
|
|
|
Egg
2 |
|
|
|
Observations
of the eggs in the vinegar:
________________________________________________________________________________________________________________________________________________
Chemical
reaction: HC2H3O2
+ CaCO3 Þ Ca(OH)2 + CO2
+ H2O
Day
2: Same eggs after being soaked in vinegar for 24 hrs.
Observations
of “vinegarized” eggs:
________________________________________________________________________________________________________________________________________________
|
|
Mass
(grams) |
Volume
(ml) |
Density
(g/ml) |
|
Egg
1 |
|
|
|
|
Egg
2 |
|
|
|
Day
3:
Observations:
________________________________________________________________________________________________________________________________________________
Egg
1 (soaked in tap water):
Egg
2 (soaked in corn syrup):
|
|
Mass
(grams) |
Volume
(ml) |
Density
(g/ml) |
|
Egg
1 |
|
|
|
|
Egg
2 |
|
|
|
Questions:
1. What did the vinegar do to the eggshell?
________________________________________________________________________________________________________________________________________________
2. Label the drawings below, showing what
happened to the two eggs between day two and day three. In the drawings titled “before”, label the
tap water and the corn syrup, and use dots to show relative concentrations in
the water, eggs and corn syrup. Also
draw arrows showing the direction of the movement of water into or out of the
eggs. Then in the drawings labeled “after”,
draw the eggs’ final sizes and appearances.
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Before:
Egg 1 Egg 2
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_files/image004.gif){kind=small}
_files/image005.gif){kind=small}
_files/image006.gif){kind=small}
After:
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Egg 1 Egg 2
3.
Define
the following terms:
a.
Diffusion
________________________________________________________________________________________________________________________________________________
b.
Osmosis
________________________________________________________________________________________________________________________________________________
4.
In
which situation was the egg in a
a.
hypertonic
solution
________________________________________________________________________________________________________________________________________________
b.
hypotonic
solution
________________________________________________________________________________________________________________________________________________
5.
Compare
the densities of the eggs in each step of the lab.
________________________________________________________________________________________________________________________________________________
6.
To
be selectively permeable means to let some substances through but not
others. Which part of this lab
demonstrated that the egg’s membranes were selectively permeable? Why?
_________________________________________________________________________________________________________________________________________
Conclusion:
In
your own words, sum up this lab. What
happened and what did it demonstrate?