Osmosis Egg Lab

Name: ______

Date: ______

Osmosis Egg Lab

Background Information:

Eggs are created with a shell covering the cell membrane. This shell is made mostly of CaCO3 taken from the bones of the hen and some proteins. The main purpose of the shell is protection of the embryo in the shell. Since the embryo is alive and must breathe the shell is porous, allowing oxygen in and carbon dioxide out. The outermost part of the shell is the cuticle, a waxy covering that helps slow the loss of water from the embryo. The cuticle is lost when the egg is washed or submerged in water or other liquid. Inside the egg there are several layers: the egg white, or albumen (with both a thin and thick layer), and the yolk. The layering of the colors in the egg is caused by the ingestion of grain and its pigments by the hen. The yolk is made up of about 50% water, 34% lipids, and about 16% proteins. The albumen is 10% proteins and is balanced in amino acids so well that it is used for measuring the value of other protein sources. The major proteins in the albumen are ovalbumin, conalbumin, and a small group called globulins.

Objective:

In this investigation you will use a fresh egg to determine what happens in osmosis. You will be measuring the amount of water that passes through the membrane lining of the shell of the egg. You will then be able to compare the data recorded by using three different substances and three eggs. You will then complete a lab write-up by using the “Lab Inquiry” model worksheet.

Materials:

1)  3 fresh eggs in shell 7) ruler

2)  200mL graduated cylinder 8) string

3)  3 clear cups 9) balance

4)  White vinegar

5)  Clear sugar solution.

6)  Distilled or bottled water

DAY 1 Procedure:

1)  Using the graduated cylinder, measure out 50mL of vinegar. Put it in one of the cups. Repeat this for each of the three cups. (Make sure to label your group’s cups with your group name.)

2)  Place each egg in separate cups 1-3. The vinegar should cover the egg. Cover the cup with plastic wrap or some other material but not tightly.

3)  Put the cups in the plastic tray on the counter for your class period and allow them to stand for 24 hours.

4)  Set up your data tables to collect measurements on all 3 eggs for the mL of fluid in the cup, circumference of the egg in mm and mass of the egg in grams for Days 2 – 4.

DAY 2 Procedure:

5)  Get your 3 cups. Carefully remove one of the eggs from the vinegar. Use your hands or one of scoops provided. It is quite fragile now as the shell is dissolved. Very gently rinse the egg with the water from the wash bottle.

6)  Measure the remaining vinegar in the cup using your graduated cylinder. Record your data(include any vinegar you may have spilled.) Dispose of the vinegar in the sink.

7)  Record your observations and the data for each of the three eggs. This includes measuring the circumference of each egg and the mass.

8)  Now label the three cups: vinegar, sugar, distilled water. Measure 50mL of vinegar and put in the vinegar cup. Measure 50 mL of sugar solution and put it in the sugar cup. Measure 50 mL of distilled water from one of the water jugs and put it in the cup labeled water.

9)  Place egg one in the vinegar, the second egg you measured in the sugar cup and the third egg you measured in the water cup. Cover the cups and put them back in the plastic tray and allow them to stand for 24 hours.

DAY 3 Procedure:

10) Carefully remove the egg in the vinegar. Repeat steps 5-6.

11) Measure 50mL of vinegar and put in the vinegar cup. Put the egg back in the vinegar.

12) Repeat these steps for the syrup and the water eggs. Be careful to put the correct egg in the correct cup.

13) Cover the jars with the lids but do not screw them on tightly. Put the jars in the plastic tray and allow them to stand for 24 hours.

DAY 4 Procedure:

14) Remove the eggs from the solutions one at a time and record your observations and draw pictures, take pictures of their appearances.

15) Discard the eggs in the container provided.

16) Measure the amount of liquid that is left in each cup. Record data.

You will now be expected to complete a formal lab writeup with all the steps.

Use the questions below in your conclusion. Make sure to answer these questions.

Questions:

1)  When the eggs were removed from the vinegar and placed in the separate liquids, in which direction did the water molecules move? Why?

2)  How do you explain the volume of liquid remaining when the egg was removed from the each of the liquids?

3)  Which solution took the longest and the shortest amount of time to reach a balance? Why?

Applications:

1)  Why do grocery store owners spray fresh fruits and vegetables with water?

2)  If a shipwrecked crew drinks seawater, they will probably die. Why?

3)  If a bowl of fresh strawberries is sprinkled with sugar, a few minutes later the berries will be covered in juice. Why?

4)  Roads are sometimes salted to melt ice. What does this do to plants around the roadside and why?

CUT OUT This Lab sheet and glue in your notebook.

1