Name: ____________________________
Block: ________
Date: __________
Bio A – Egg Osmosis Lab Activity (38 points)
Introduction: When a cell in placed into a solution, changes occur. Water can go in or out of the cell causing it
to swell, burst, or shrivel causing a change in mass. An egg is a single cell, so all of these changes are readily
visible after it is de-shelled. You can compare what you will see here to any human cell as the changes in solute
and water concentrations cause cells to shrivel, as you see in your skin, or burst if you are placed into the wrong
type of solution.
Materials:
Egg
Vinegar
Vegetable oil solutions
Paper towels
Beakers
Balance
Graph paper
Procedure:
1. Dissolve the shell of the eggs in a vinegar (5% acetic acid) solution. The more you use, the quicker it
dissolves. This can take approximately 24 to 48 hours. Afterwards, remove the egg and carefully dry it.
Write down your initial observations.
2. Take out the eggs and weigh the egg to get the mass of a de-shelled, dry egg (“initial” mass). When
drying it, be very careful as it only has a weak, thin membrane. It is raw as well, so be sure to wash your
hands after handling it.
3. Make 1 of the following solutions: 0%, 20%, 40%, 60%, 80%, and 100% vegetable oil.
The assigned percentage is the percent of corn syrup to be dissolved in final volume of 500 ml of water.
For instance, a 40% corn syrup solution (of a 500 ml solution) is composed of 200 ml corn syrup and
300 ml distilled water. Each group will do 1 solution.
4. Let the de-shelled egg sit in the solution for up to 48 hours. Afterwards, take it out and dry it off.
Write down your observations.
Observations
Before being put into solution (1 point)
After being put into solution (1 point)
5. Determine the dry mass using a balance. This is the “final” mass.
6. Subtract the “initial” mass from the “final” mass. This is the change in mass.
7. Calculate the percent (%) change in mass. Percent change is mass is calculated by using the formula:
[(final mass – initial mass) / (initial mass)] x 100%. This value will be either a positive number,
showing a gain in mass, or a negative number, showing a loss in mass.
8. Put your data on the board so that the others can copy your data. Copy the other groups’ data.
EGG
Percent
Syrup
1
2
3
4
5
6
0%
20%
40%
60%
80%
100%
Mass Before
(g)
Mass After
(g)
Change in
Mass (g)
Percent
Change in
Mass (%)
(0.5 points per box, 12 points total)
9. Construct a graph of percent change in mass versus percent corn syrup from the class data on the
board. Be sure to provide a title and include labels and units for each axis of the graph. (5 points)
10. Draw a best-fit line for the data points. (1 point)
Analysis Questions: (Answer each of the following in COMPLETE SENTENCES)
1.
A. What was your group’s percent vegetable oil solution? What happened to the egg in your solution?
(2 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
B. Was your solution hypotonic, hypertonic, or isotonic? Explain how you know. (2 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
2. Briefly describe what would happen to the egg in ALL of the following types of solutions: hypotonic,
hypertonic, and isotonic. (3 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
3. What approximate percent of corn syrup would be an isotonic solution for the egg? Explain how you know.
(2 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
4. Find and explain a real-world example for 2 of the following types of solutions: isotonic, hypertonic, or
hypotonic. (4 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
5. What could have caused the data to be so spread out? What can be done to improve the data and make it more
consistent? (2 points)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
6. Based on your graph, answer the following:
A. What is the percent corn syrup when there is a 6% change in mass? (1 point)
__________________________________________________________________________________________
__________________________________________________________________________________________
B. What is the change in mass in a 10% corn syrup solution? (1 point)
__________________________________________________________________________________________
__________________________________________________________________________________________
C. What conclusion can be drawn from the graph? (1 point)
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________