Osmosis and the Incredible Egg Instructions

Purpose: To look at the effects of hypertonic and hypotonic solutions on the process of osmosis through a membrane.

Background: An egg is like a giant cell. It has a membrane on the outside and the membrane is covered by a shell. We can remove the shell of the egg by soaking it in vinegar, then what we are left with is a model of the cell. We are going to look at how hypertonic and hypotonic solutions effect osmosis in a cell.

Problem: ______

Independent Variable: ______

Dependent Variable: ______

Control: ______

Constant: ______

Hypothesis:

  1. What do you think will happen when the decalcified egg is placed in syrup?
  1. What do you think will happen when the decalcified egg is placed in water?

Materials:

-2 decalcified eggs

-paper towels

-2 Cups

-spoons

-water

-syrup

Procedure:

1)Label 1 Cup Water. Label the other cupSyrup.

2)Get 2 decalcified eggs.

3)Place one egg in each cup.

4)Measure 100 mL of water and place in the water cup with the egg.

5)Measure 100 mL of syrup and place in the syrup cup with the egg.

6)Examine and record the color and appearance of the water.

7)In the “syrup” cup pour syrup to cover the egg. Record the time the egg was put into the syrup.

8)Examine and record the color and appearance of the syrup.

9)After 5 minutes have gone by use the “water” spoon to remove the egg from the water and the “syrup” spoon to remove the egg from the syrup.

10)Dry each egg of very well and use the balance to measure the mass of each egg. Record the mass of each egg on the data tables.

11)Repeat steps 8 and 9 every 5 minutes until the teacher calls time to clean up.

12)After you have removed the eggs from the liquids the last time, record the appearance of the liquids on the data table.

Data Tables

Water Egg / Syrup Egg
Time (minutes) / Mass (grams) / Percent Mass Change / Time (minutes) / Mass (grams) / Percent Mass Change
0 / 0
5 / 5
10 / 10
15 / 15
20 / 20

Calculate Percent Mass change with the equation below:

(mass when you take it out – mass when you started) x 100

Mass when you started

Appearance of fluids
Initial description / Final description
Water
Syrup

Graph 1: Use your data about percent mass change above to complete the graph

Line for egg in syrup:Line for egg in water:

Questions:

1)What did this lab help you learn about?

2)What is osmosis?

3)Define a hypertonic solution.

4)In the lab which solution was hypertonic to the egg?

5)Define a hypotonic solution.

6)In the lab, which solution was hypotonic to the egg?

7)Use the words hypotonic and hypertonic explain why the mass of your eggs changed over time.

8)Were there any changes in the color of the water or syrup? If there were why do you think they changed color?

9)What would happen to the eggs if you left them in the liquids for longer?

10)What would happen to a human body cell if you put it into salt water?

11)What would happen to a human body cell if you put it into pure water?