Name: _______________________
Date: __________
Investigation: Osmosis with Gummi Bears
Purpose
To investigate the movement of water into and out of a polymer
through a semipermeable membrane
Background
Gummi Bears are made of gelatin and sugar. Gelatin is a polymer that forms
large three-dimensional shapes, which give structural support to jellies and
jams. The sugar molecules are able to move in and out of the gummibear
when it is immersed in water. Water is also able to move into and out of the
gummibear.
Research Question
Will soaking Gummi Bears in tap water and salt water affect the volume
and/or mass of a gummi bear?
Hypothesis: If we soak the gummy bear in tap water then it will______.
If we soak the gummy bear in salt water then it will______.
Materials
o (2) Gummi Bears
o (2) paper cups (6oz)
o tap water
o Centimeter ruler
o Salt solution
o Paper towels
o balance
o marker
Procedure
1. Obtain two paper cups and two different color bears.
2. On the side of each cup, write your name and period using a permanent
marker. Decide which solutions you would like to test. Your choices
are tap water, salt water, distilled water, and concentrated salt
water. Write your choices on your two cups, labeling which will have
which solution.
3. Find the mass of each bear using a balance. Record the data in the
data table. Keep the bears in the cup when measuring mass.
4. Measure your bears from top to bottom (height), from side to side
(length) and from front to back (width). Use your measurements to
calculate the volume. (​l x w x h​) Record your data in the data table.
5. Pour your first solution in the appropriate cup; enough to fully cover
the bear.
6. Pour your second solution in the appropriate cup;enough to fully cover
the bear.
7. Place the cups on the counter in the location set aside for your class
as indicated by your teacher.
8. On the next lab day (Thursday), gently pour the water from each cup
out into the sink. Be careful, do not drop your bear, it is very fragile.
(GENTLY) Blot any excess water with a paper towel.
9. Find the mass of each bear. Do this by placing the entire cup with the
bear on the balance. Record the total mass. Remember to subtract the
mass of the cup afterward, once you remove the bear. Then find the
volume of the bear.
Data Table for ​Mass​:
Solution 1:
Before ​solution
Mass (grams) 1​ (day 1)
Color of
Gummi Beat
Mass of
gummi bear
in cup
Mass of cup
Solution 2:
After ​solution
Before ​solution
1 ​(day 2)
2​ (day 1)
After ​solution
2​ (day 2)
After ​solution
1 ​(day 2)
After ​solution 2
(day 2)
Total mass=
(gummi bear in
cup)-(mass
ofcup)
Data Table for ​Volume​:
Before ​solution
Dimensions
1​ (day 1)
Height (cm)
Length (cm)
Width (cm)
Volume
Before ​solution
2​ (day 1)
Analysis Questions
Using your own data, and that of your classmates, calculate the percent
change in volume of the gummi bears in each
of the four solutions:
Tap:
Distilled:
Salt:
Concentrated Salt:
1. What happened to the bear when placed in your first solution? Why?
2. What happened to the bear when placed in your second solution?
Why?
3. Was there a difference in your results between the two solutions? If
so, why?
4. What do you think would have happened to the salt water bears if,
after the last day, they were placed into tap water?
5. Make a bar graph of the percent changes on the last page.
a. Label the axes, horizontal-tap water bear, salt water bear,
distilled water bear, concentrated salt water bear.
Vertical axis- scale based on percent change of volume.
b. Give the graph a title. Place the data for all the bears on the
same graph. Use the graphing box on the next page.
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.)
6. Write a paragraph that explains the r​ esults​ of this experiment using
the concept of osmosis. Include your data where appropriate to
explain your results.​(5-7 sentences) Use the TEA EAT format you
learned in English class.