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This experiment is courtesy of 
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Biodegradability
The Elusive Disappearing Act
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Developers:
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Sister John Ann Proach, OSF
Bishop Conwell High School
Levittown, PA t
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Robert M. Amici
Richard A. Einhorn
Rohm and Haas Company
Bristol, PA
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Grade Levels:
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Grades 7 through 12
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Discipline:
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Environmental Science, Chemistry, Physical Science
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Goal:
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The students will be able to explore the concept of
degradability and biodegradability and study its effects on
the environment.
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Objectives:
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- To study the effects of water, salt water and heat on
common household materials.
- To separate an emulsion and show that the materials
are completely recoverable.
- To observe the effect of acetone and water on
polystyrene.
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Background:
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Today, there is great concern for the environment, and a
current environmental issue that confronts the scientists,
politicians and educators is biodegradability. Where are all
the materials that we hope to dispose of really going? What
happens when we throw something away?
Years of research in chemisty, polymer science and
technology have produced new plastics which have made life
easier and more convenient. Polymers have been developed
which are able to retain their strength by resisting the
break down of their molecular composition caused by light,
air and water . This enabled consumer products made of these
polymers to be very effective in many applications. Because
of their light weight and durability, plastics have become a
commonplace material in the lives of the consumer.
Since many plastics are used in 'throw-away' packaging
applications, an environmental issue has arisen concerning
the use, recycling, and disposal of these materials. Can we
reduce our landfill needs by reducing the amount of plastics
that we discard? For any material to decompose, chemical
bonds must be broken by bacteria, fungi, microorganisms,
water in the soil, sunlight or by some other means. From
studies so far we see that this process takes time, and time
seems to be running out for Planet Earth. What are some
possible answers to the problems of disposal? Is
degradability and biodegradability the answer?
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Materials:
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Part I - per team
8 pieces ( 5 cm square) of materials to be tested ex.
paper cup, plastic milk container, newspaper, paper bag,
poly (vinyl chloride) (PVC), plastic bottle, aluminum foil,
etc.
16-250-mL beakers
1 hot plate
1 pair of beaker tongs
1balance (reading to two decimal places)
13% salt solution or simulated sea water
water
marking pen or pencil
goggles
aprons
hot pads or gloves
Part II A-- per team
2 grams of calcium chloride dihydrate, CaCl2 2H2O
100 mL water
Latex paint (not oil based)
thermometer
hot plate
glass stirring rod
2-250-mL beakers
balance ( reading to two decimal places)
1-100-mL graduated cylinder
goggles
aprons
hot pads or gloves
Part II B - per team
1-250-mL beaker
glass stirring rod
weighing dish
pipette
hot plate
balance (reading to two decimal places)
goggles
aprons
hot pads or gloves
Part III - Demonstration
balance (reading to two decimal places)
2- 400-mL beaker
1-100-mL graduated cylinder
100 mL of acetone
400 mL of water
polystyrene packing peanuts
glass stirring rod
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Procedures:
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Part I - Solid - Non-Degradable - Here to Stay
- Obtain 16 250-mL beakers and label 8 beakers "water"
and 8 beakers "salt water."
- Obtain 2 pieces each (5cm square) of the materials to
be tested such as paper plates, paper cups, newspaper,
aluminum foil, PVC bottle, milk container plastic.
- Weigh each piece of material and record the mass in
Data Table 1.
- Fill 8 beakers with 100 mL of water and 8 beakers
with 100 mL salt water.
- Place one piece of each material selected in a beaker
of salt water and one in a beaker of water.
- Place the beakers on the hot plate and heat to
boiling. Continue heating for 15 minutes.
- Note any changes in each of the materials as they are
heating.
- After 15 minutes of heating, remove the beakers from
heat and with your forceps remove each piece of material
from the beakers and place the materials on a paper towel
to dry.
- The materials may have to dry overnight.
- Reweigh the materials and record the masses in Data
Table #1.
- Compare your results and answer the questions for
Part 1.
Part II A - Plastic Dispersion - Gone But Not
Forgotten
- Weigh 2 grams of CaCl2 2H2O and
place in a 250-ml beaker. Add 100 mL of water. Stir and
place on a hot plate.
- Heat the CaCl2 solution to between
85�C to 90�C .
- While the solution is heating, obtain another 250-mL
beaker and place 20 grams of latex paint in the beaker.
Add 10 mL of water to the beaker and stir until
homogeneous .
- When the CaCl2 solution reaches between
85�C to 90�C , slowly add the diluted paint to
the CaCl2 solution while on the hot plate.
- Continue to heat the mixture for 10 to 15 minutes,
stirring constantly.
- Remove from the hot plate and allow to cool.
- Observe the material in the beaker and complete the
questions for Part II A.
Part II B -Determination of the Percent Solids of a
Latex Paint
- In a 250-ml beaker, dilute 10 grams of paint with 20
mL of water.
- Record the mass of a weighing dish in Data Table 2B.1
- Add 1.5 to 2.0 grams of the diluted paint to this
weighing dish.
- Place the weighing dish on a hot plate and begin
heating it at a low setting. Do not let the suspension
splatter.
- Record your starting time .
- At one-minute intervals, remove the weighing dish
from the hot plate and reweigh it. Record your reading in
the proper place on Data Table 2B.2.
- Place the weighing dish on the hot plate and continue
heating and reweighing the material at one minute
intervals until the mass of the dish remains constant for
two consecutive readings.
- Remove the dish from the heat and allow to cool. Take
the final reading of the dish and calculate the percent
solids.
- Graph your data from Data Table 2B.2 on Graph 2B.2
Refer to Sample Data Table 2B.2 and Sample Graph 2B.2
- Complete your observations and answer the questions
from Part II B
Part III - Demonstration- You Think I'm Gone But I'm
Not
- Take a 400-mL beaker and fill it with 200-mL of
water.
- Add a few packaging "peanuts" to the water.
- Observe the reaction of the water and the "peanuts."
- Fill another 400-mL beaker with 100 mL of acetone.
- Weigh a few packaging "peanuts" and record their
mass.
- Take approximately 50 - 100 packaging "peanuts" and
continually add them to the beaker with the acetone.
- Observe what happens to the "peanuts" as each is
added to the acetone.
- Estimate the total weight of the "peanuts" added to
the acetone.
- Predict what would happen to the contents of the
beaker when you would add 200-mL of water.
- Add 200-mL of water to the contents of the beaker.
- Filter the contents of the beaker and weigh the
material.
- Make your observations and answer the questions to
Part III.
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Questions:
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Part I
- What was the purpose of heat in this experiment?
- What were the changes observed in the water and salt
water?
- What do the changes in the water mean for the
environment?
- If these materials were degradable, what would you
expect to see? If these materials were biodegradable,
what would you expect to see?
Part II A
- Describe the appearance of the CaCl2
solution and the paint emulsion upon mixing.
- Describe the final appearance after heating the
solution for 15 minutes between 85�C and 90�C.
- Do you think you have the same material that you
began with? Why?
- Where do you think the precipitate came from?
- What does this tell you about paint?
- Is this a qualitative or quantitative observation?
Why?
- If a plastic disperses in a liquid, does this mean it
is degradable?
- If a plastic disperses in a liquid, does this mean it
is biodegradable?
Part II B
- While heating the dish with the paint, what was given
off?
- From your calculations in the experiment, what would
be the percent of solids obtained for a solution of 10
grams of paint and 30 grams of water? 40 grams of water?
- Why did you weigh the dish at one minute intervals?
- What percent water was in your sample of paint
solution?
- From this experiment, what general conclusion can you
make about degradability? biodegradability?
Part III
- What happens to the packaging "peanuts" when added to
the beaker with water?
- What was the approximate mass of 5 packaging
"peanuts."
- What was your prediction of the number of peanuts
that could be placed into the acetone in the beaker?
- What is the approximate mass of all the packaging
"peanuts" that were added to the acetone?
- As the peanuts are placed in the acetone, describe
what is happening?
- What do you think causes the "fizzing" heard?
- Does the acetone degrade the peanuts?
- What role does the water play in the experiment?
- If the plastic disperses in the liquid, does it mean
that it is degraded? biodegraded?
- After you filtered the contents of the beaker, what
was the approximate mass of the material?
- What can you conclude about the material you isolated
inrelationship to the starting material?
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Table Data:
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Data Table I
Sample Identfication
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Water Exposure
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Salt Water Exposure
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Data Table 2B.1
Mass of Paint and Dish
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Mass of Dish
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Mass of Paint
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Percent Solids
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Sample Data Table 2B.2
Time
(Minutes)
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Mass
(grams)
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2.87
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2.48
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2.16
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1.86
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1.61
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1.40
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1.32
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7
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1.31
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1.30
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9
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1.30
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10
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1.30
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Data Table 2B.2
Time
(Minutes)
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Mass
(grams)
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0
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1
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2
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3
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4
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5
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9
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10
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11
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12
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14
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15
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Data Graphs

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Procedure For Calculations:
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Discussion Questions:
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- What does degradability mean?
- What does the term biodegradability mean?
- Is biodegradability good for all materials? Why?
- What things would you not want to be biodegradable?
- What are the conditions required for
biodegradability?
- What are some ways in addition to biodegradability
that will help the environment?
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References:
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Part III Demonstration was adapted from "Project LABS"
Rohm and Haas Co. 1990, pg. 27-28.
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Extension Activities:
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- Many companies are trying to capitalize on the
biodegradability theme by offering "green" materials,
i.e. their product as biodegradable. But are they really?
Go through the supermarket and stores and list all of the
products that claim to be biodegradable. Design possible
ways to test their claim.
- As part of the extension activity in #1, select
materials that you could subject to a long term exposure
study. These materials could be buried, or put in a
water-filled trash can for months, weighing the materials
every so often to determine if they degrade.
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Teacher Notes:
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If CaCl2 is not available in Part II A of the
experiment acetic acid may be substituted. Two mL of acetic
acid may be added to 100 mL of water. The results would be
the same. Please Note: When heating the acetic acid place
the hot plate in a hood or heat the solution in a well
ventilated room. The fumes created from heating acetic acid
can be irritating to the respiratory tract and eyes.
In Part IIA milk could be tried instead of paint with the
acetic acid. This could be filtered at the end and other
activities could be developed.
In Part IIB of the activity, Determination of the Percent
Solids, Elmer's Glue� can be substituted in the place of
latex paint.
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This experiment is courtesy of 
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