Lesson Title: Osmosis and Diffusion: Egg Lab
Discipline Focus: Biology
Grade level: 10th Grade
Length of lesson: 4 Days
Stage 1 – Desired Results
Content Standard(s):
Minnesota Academic Standards in Science
Grade Level: 9-12, Strand IV: Life Science, Sub-Strand: Cells
Standard: The student will comprehend that all living things are composed of cells, and
that the life processes in a cell are based on molecular interactions.
Benchmarks: (3) The student will explain the role of the cell membrane as a highly
selective barrier in diffusion, osmosis and active transport.
Understanding (s)/goals
Essential Question(s):
Students will gain an understanding of how This lesson aims at questioning if students
and why diffusion and osmosis takes place
are able to distinguish between hyper,
in an egg cell.
hypo and isotonic solutions.
Student objectives (outcomes):
Students will be able to:
♦ Demonstrate diffusion across a semi-permeable membrane
♦ Measure the effects of various concentrations of solute in the process of osmosis
♦ Differentiate between hypotonic, isotonic, and hypertonic environments
Stage 2 – Assessment Evidence
Performance Task(s):
Other Evidence:
♦ Develop a hypothesis explaining
♦ Show participation throughout the four
the movement of water molecules
day lab duration.
across the semipermeable
membrane of an egg in four
different solutions.
♦ Complete 4 data tables including:
qualitative observations, egg mass,
egg circumference, and solution
volume.
♦ Provide answers to analysis
questions at completion of the lab.
Stage 3 – Learning Plan
Learning Activities:
Materials & Resources:
4 eggs, 4 plastic cups, Graduated cylinder, Vinegar, Tap water, Corn syrup, Salt water,
Other liquid of choice (brought in by instructor), String, Ruler, Digital scale, Masking
Tape, Sharpie, Paper towels, Lab notebook
Timeline:
DAY 1
Introductory Activity: PowerPoint describing vocabulary terms they will need to be
familiar with and an explanation on this week’s lab.
♦ The students have been introduced to diffusion and osmosis this week so I will
quickly ask them to describe what each of the terms mean. I will then describe
selectively permeable membrane and explain the difference between solvent, solute
and solution. The terms hypotonic, hypertonic and isotonic will be described verbally
and through an illustration drawn on the smart board.
♦ An explanation on this week’s lab will be given describing what needs to be done on
Day 1, 2 and 3 and the measurements that need to be taken. I will show them how
to use a digital scale, review how to measure with a graduated cylinder and how to
measure the circumference around the egg. I will then show the four tables that
need to be filled out this week and each student will draw this into their lab
notebook.
♦ We will then get into the lab. Students will be divided into groups of 4 and each
group will be given 4 eggs, 4 plastic cups and vinegar. The students will place one
egg in each cup and pour vinegar over each egg. The vinegar will not need to be
measured out, however there should be enough vinegar so that the egg is covered.
The calcium carbonate shell will dissolve over the weekend. Once finished in the lab
students will form hypotheses and decide on a fourth solution of their choice.
DAY 2
Lab Activity
♦ Obtain group eggs, pour off vinegar, measure the initial circumference and mass of
each egg and describe initial qualitative observations. Record in data tables in lab
notebook.
♦ Rinse out plastic cups.
♦ Pour 125 mL of tap water into one of the cups. Pour 125 mL of saltwater into a
second cup. Pour 125 mL of corn syrup into a third cup and 125 mL of solution of
choice into the fourth cup.
♦ Continue to develop hypotheses if not yet completed.
DAY 3
Lab Activity
♦ Obtain group eggs, pour remaining solution into a graduated cylinder and record
volume remaining.
♦ Make qualitative observations and circumference and mass measurements on each
of the four eggs. Record in data tables.
♦ Pour solution from graduated cylinder back into the plastic cup and place egg back
in solution. Allow egg cell to soak over a three day period.
DAY 4
Lab Activity
♦ Make final observations and measurements (volume, circumference and mass).
♦ Dispose of eggs and solutions.
♦ Answer data analysis questions with group members.
♦ Discuss as a class the results and the explanations behind these results.
Closing Activities
This lesson will be summarized as a class at the completion of the activity. I will have
the students share their results with the class. I would then like to have a class
discussion on what was happening to the egg cell in each of our solutions. We will
discuss why the egg cell gained or lost weight and why there may have been a change
in solution volume. The students will then be able to better understand a hypertonic,
hypotonic and isotonic solutions and how each of these environments is affecting
osmosis in a cell.
Osmosis & Diffusion: Egg Lab
Objective:
♦ Demonstrate diffusion across a semi-permeable membrane
♦ Measure the effects of various concentrations of solute in the process of osmosis
♦ Differentiate between hypotonic, isotonic, and hypertonic environments
The objective of this experiment is to detect diffusion and osmosis across a selectively
permeable membrane. We will be using shell-less chicken eggs placed in four different
solutions including: distilled water, salt (NaCl) solution, sucrose solution and a substance
of your choice over a period of three days.
Definition Review:
Diffusion: The spontaneous movement of molecules or particles in solution along a
concentration gradient (i.e. from areas of high concentration to a low concentration) until
there is an equilibrium.
Osmosis: The diffusion of water molecules through a selectively permeable membrane
from a region of low solute concentration to a region of high solute concentration.
Selectively Permeable Membrane: A membrane that allows only certain materials to pass
through it by diffusion.
Solvent: A liquid that dissolves a solute resulting in a solution (example: water).
Solute: Dissolved in another substance known as a solvent (example: salt).
Solution: A mixture made-up of solutes and a solvent (example: salt water).
Hypotonic: A condition in which the inside of the cell has a higher solute concentration
than its environment. Osmosis causes a net flow of water into the cell, causing swelling
and expansion. This swelling may cause cells without a rigid cell wall to burst.
Hypertonic: A condition in which the environment has a higher solute concentration than
inside the cell. Osmosis pressure causes water to flow out of the cells and causing the cell
to shrink.
Isotonic: A solution with equal concentration of solute inside and outside of the material.
Materials:
4 eggs
Distilled water
Rubbing alcohol
Digital scale
Lab Notebook
4 plastic cups
Corn syrup
Food coloring
Masking Tape
Graduated cylider
Salt water
String
Sharpie
Vinegar
Soda
Ruler
Paper towels
Procedure:
DAY 1
You will begin by removing the eggshell with vinegar. How does this work? When you
submerge an egg in vinegar, the shell dissolves. Vinegar contains acetic acid, which
breaks apart the solid calcium carbonate crystals that make up the eggshell into their
calcium and carbonate parts. The calcium ions float free (calcium ions are atoms that are
missing electrons), while the carbonate goes to make carbon dioxide—the bubbles that
you see. The eggs are still surrounded by a thin – selectively permeable – shell
membrane. Be careful these are fragile. (If you break an egg you will be cleaning up the
classroom)
1) In four plastic cups, pour 100 mL of vinegar.
2) Place a raw egg GENTLY into each of the cups of vinegar.
3) Allow the eggs to sit over the weekend.
Questions:
On Monday you will be placing each egg in four different solutions: Tap Water, Corn
Syrup, Salt Water and a substance of your choice.
1) Based on what you know about diffusion and osmosis develop a hypothesis explaining
the movement of water molecules across the semipermeable membrane. Include if you
think the solution is hypotonic, hypertonic, or isotonic
a) Tap Water
b) Corn Syrup
c) Salt Water
2) Will the eggs gain or lose weight in the Tap Water solution?
3) Will the eggs gain or lose weight in the Corn Syrup solution?
4) Will the eggs gain or lose weight in the Salt Water solution?
5) Each group will need to propose a treatment for a fourth egg. Based on what you
know about osmosis and the experimental setup, propose a treatment for this additional
egg. Each group will decide on this extra treatment and propose it to Mrs. Sloan.
Examples of materials that will be available to you include: food coloring, rubbing
alcohol, soda (i.e. 7up, coke, etc), cleaners, soap, etc.
DAY 2
1) Carefully remove eggs from the vinegar solution.
2) Rinse the eggs off with cold water and gently blot each of them dry with a paper towel.
3) Make qualatative observations (color, shape, texture, smell, and any other notable
characteristics) on each of the eggs and record these observations in your lab notebook.
Measure Circumference of the Eggs:
4) Wrap a piece of string snugly around each egg at the equator, be careful not to cut into
the egg’s membrane with the string.
5) Keeping your finger on the point at which the string circled the egg, lay the string
straight on the lab bench.
6) Use a metric ruler to measure the distance from the end of the string to this
circumference point and record this measurement in your lab notebook.
Measure Mass of the Eggs:
7) Weigh each of the eggs by placing them on an electric scale. Record the weight for
each egg to the nearest 0.1 gram in your lab notebook
8) Pour remaining vinegar down the drain and rinse each of the cups.
9) Label four plastic cups with Tap Water, Sucrose, Salt and solution of your choice.
In one cup, pour 125 mL of tap water
In a second cup, pour 125 mL of corn syrup
In a third cup, pour 125 mL of salt water
In a fourth cup, pour 125 mL of chosen solution (i.e. rubbing alcohol, soda, colored
water, soap, etc)
10) Carefully place one egg in each of the above solutions. MAKE SURE TO LABEL
WHICH EGG IS IN EACH SOLUTION ON YOUR DATA SHEET IN YOUR LAB
NOTEBOOK.
11) Allow eggs to sit overnight.
DAY 3
1) Carefully remove eggs from the each of the solutions.
2) Rinse the eggs off with cold water and gently blot each of them dry with a paper towel.
3) Make qualatative observations (color, shape, texture, smell, and any other notable
characteristics) on each of the eggs and record these observations in your lab notebook.
4) Measure the circumference of each of the eggs and record this value in your lab
notebook
5) Weigh each of the eggs by placing them on an electric scale. Record the weight for
each egg to the nearest 0.1 gram in your lab notebook.
Measure Volume of the Solution:
6) Pour the remaining solution from the plastic cup in a graduated cylider and record its
volume in mL in your lab notebook. Repeat this step for each of the cups.
7) Pour solutions down the drain and rinse each of the cups. Dispose of the eggs.
Record results in the following data tables:
Qualitative Observations
Solution
Vinegar
Tap Water
Salt (NaCl)
Sucrose
Before Placement in Solution
Changes in Appearance/Characteristics
after Placed in Solution
Solutions
Egg Measurement
Initial
Final
Circumference
Circumference
(cm)
(cm)
Change in Size
(cm)
Tap Water
Salt (NaCl)
Sucrose
Mass of the Eggs
Solutions
Initial Mass
(grams)
Final Mass (grams)
Change in Mass
(grams)
Tap Water
Salt (NaCl)
Sucrose
Solutions
Tap Water
Salt (NaCl)
Sucrose
Volume of Solution
Final Volume:
Initial Volume:
amount present
amount placed in
AFTER the egg
the cup (mL)
was removed (mL)
Change in Volume
(mL)
Questions:
1) An egg is the largest cell in the world. After the shell was removed, what organelle was the
thin white layer around the
egg (keeps the outside out and the inside in)?
2) Was there more or less liquid in the beaker after the egg had been in the corn syrup overnight?
Why do you think this is so?
3) Was there more or less liquid in the beaker after the egg had been in the water overnight?
Why do you think this is so?
5) A solution that has LOTS of solute and causes a cell to shrivel is known as
What is an example of this type of solution in this lab?
6) A solution that has LOTS of solvent and causes a cell to burst is known as
What is an example of this type of solution in this lab?
7) Which solutions were hypertonic, isotonic or hypotonic? Explain how you know.
8) What happened to the weight of the egg in your special treatment? Does this mean it was a
hypertonic, hypotonic, or isotonic solution?
9) What is one question you have about osmosis after this lab?