Osmosis with Gummi Bears Names: ______
______
______
Purpose
To model osmosis using gummy bears.
Background
Gummi Bears are made of gelatin and sugar. Gelatin is a polymer that forms large three-dimensional matrices, which give structural support to jellies and jams. The matrices act similar to a selectively permeable membrane in that certain molecules will freely pass, while other will be unable to pass.
Materials
o (3) Gummi Bears
o (3) medium beakers and (1) small beaker
o Distilled water
o Centimeter ruler
o Sugar
o Paper towels
o Scale
o Masking tape
o Permanent marker
o Plastic fork and spoon
Procedure
1. Obtain two beakers and two different colored gummy bears.
2. Put a piece of tape on each beaker and write your name and using a permanent marker. Mark one beaker for tap water, one for distilled water, and one for sugar solution.
3. Find the mass of each bear using a scale. Record the data in the data table.
4. Measure your bears from top to bottom (length), from side to side (width) and from front to back (height). Use your measurements to calculate the volume. Record your data in the data table.
5. Place the bears in the cups.
6. Pour distilled water in the cup marked distilled. Pour enough water in the cup to fully cover the bear. Record the amount of water you are using here: ______mL
7. Pour tap water in the cup marked tap. Pour enough water in the cup to fully cover the bear. You must use the same amount as you did of distilled water
8. In the third beaker, put the same amount of distilled water as before, but add sugar. You are trying to guess what amount of sugar will make the solution isotonic or hypertonic to the gummy bear. Record the amount of sugar you used here: ______g
9. Place the beakers on the cart and let them soak overnight.
10. Answer the following questions:
o The distilled water will be ______to the gummy bear, causing water to ______. The gummy bear will ______.
o The tap water will be ______to the gummy bear, causing water to ______. The gummy bear will ______.
o The sugar solution will be ______to the gummy bear, causing water to ______. The gummy bear will ______.
Next Day:
1. Gently pour the water from each beaker into the sink. Catch the gummy bear with a plastic fork.
2. Catch each bear on a separate fork. While on the fork, measure the height, width, and depth. Calculate the volume. Record your data.
3. Blot the bear dry by placing it on a paper towel.
4. Find the mass of each bear. Do this by placing several paper towels on the scale, then zeroing it out. Then, place the bear on the scale. Record the total mass. Carefully slide the bear back into the empty cup.
5. Record the bear’s mass.
RESULTS:
Data Table for Mass:
Gummi Bear 1 (color:______) / Gummi Bear 2 (color:______) / Gummi Bear 3 (color:______)Mass (grams) / Before tap water (day 1) / After tap water (day 2) / Before distilled water (day 1) / After distilled water (day 2) / Before sugar solution
(day 1) / After sugar solution
(Day 2)
Mass of gummi bear
Data Table for Volume:
Gummi Bear 1 (color:______) / Gummi Bear 2 (color:______) / Gummi Bear 3 (color:______)Dimensions / Before tap water (day 1) / After tap water (day 2) / Before distilled water (day 1) / After distilled water (day 2) / Before sugar solution
(day 1) / After sugar solution
(Day 2)
Length (cm)
Width (cm)
Height (cm)
Volume (cm3)
QUESTIONS:
Number, write, and underline the questions first and then answer them.
1. What happened to the bears when placed in distilled water? Why?
2. What happened to the bears when placed in tap water? Why?
3. Was there a difference in your results using tap water compared to distilled water? If so, why?
4. What happened to the bears when placed in sugar water? Why?
5. What do you think would have happened to each of the bears if, after the last day, they were again placed in distilled water?
6. Calculate the percent change in volume and mass after each step of the experiment.
a. % change in volume = (final volume - initial volume)/ initial volume x 100
b. Replace the words “volume” with “mass” to find the percent change in mass.
c. Place the percentages in the table below:
Bears / % Change Volume / % Change MassTap Water Bear
Distilled Water Bear
Sugar Water Bear
7. Make a bar graph of the percent changes below.
a. Label axes
b. Place a scale on the vertical axis and give the graph a title. Place the data for both bears on the same graph. Use the color of the bear on the graph to represent that bear.
c. If you have a negative value for a percent change, start the vertical axis at a negative number. (For example: -50, -25, 0, 25, 50, 75, 100, etc.)
8. Write a 5-10 sentence conclusion. Discuss what you did, what happened, and why it happened. If there were any anomalies, try to explain them. Mechanics count, so write well.
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