Adventures With Super-Adsorbers and Substance Solubility

Disposable Diaper Comparison and Mystery-powder Identification

1. Use the scientific method to determine which disposable diaper absorbs the most water and most saline water.
   
2. Identify when a piece of diaper is SATURATED with water.
   
3. Observe how polyacrylate rapidly absorbs water.
   
4. Compute percentage of water absorbed by disposable diapers.
   
5. Identify six unnamed powders based on their color, appearance and reaction to hot and cold water using a Table of Physical Properties.
   
6. Work as a scientific team with specific assigned jobs.
   
7. Evaluate his/her team's success as a team by identifying behaviors which helped team achieve its goal.

Of course, the environmental issue concerning disposal of sodium polyacrylate-filled diapers and polyacrylamide-enriched soil is a springboard for discussion as these materials are NOT biodegradable. On the other hand, the convenience, sanitary properties and environmental cost (ie: pesticides and bleaching process) for producing cotton diapers needs also to be considered. Finally, the ability of polyacrylamide to help produce crops which can feed many people is also an issue.

Whereas the polymers discussed above ABSORB water, other powders and crystals may DISSOLVE in water and form a SOLUTION. When soluble powder or crystals are dissolved in a container of water, the solid is no longer identifiable. When no more of the solid can be dissolved in water, the water is said to be SATURATED: identifiable pieces of the solid fall to the bottom of the container or float on top. Hot and cold water may affect the rate at which a substance is dissolved.

Sodium polyacrylate is listed as being non-toxic. Before beginning the activity, however, it would be wise to ask if any of the students are alllergic to disposable baby diapers. One child in my class developed a rash on her arms from touching the substance and later told me that she thought she was allergic to disposable diapers when she was litttle. She is allergic to many other substances, especially metals and zippers. I would suggest letting a child like this be an observer and /or recorder.

EXPERIMENT 1: HERE, YOU TAKE THE BABY! ICK!

Materials for each group:

2 identical glass jars or clear plastic cups (approx. 200 ml) labeled A and B.

1 graduate cylinder (100 ml)

1 balance or scale (optional: use to weigh table salt)

2 precut 2 inch square pieces of 2 BRANDS of disposable baby diapers labeled A and B. (Hint: Ask students to bring in diapers a few days before lesson. It will help save money and students will naturally "root" for the diaper they bring in! If using more than two brands, compare only two at a time or adjust the materials and student lab sheet to suit your needs).

1 lab sheet

10 g or 10 ml of sodium chloride (ordinary table salt) tap water

2 containers for disposal of wet diaper samples (One larger container for the salt solution samplesand one for the tap water samples is sufficient for the whole class. Save if intending to plant seeds in the wet super absorber, see Extension Activity 3-b).

1. Divide class into groups of 4.
   
2. Assign cooperative jobs: Leader / Reader, Recorder, Custodians (gets materials and cleans up), Encourager / Gatekeeper (assures equal opportunities to "do" the activity).
   
3. Explain experiment and review lab sheets (make a copy for each group.).
   
4. Group members make observations about dry diaper samples. Discuss possible outcomes and write down their hypothesis of best diaper on lab sheet .
   
5. Groups measure 100 ml of tap water into each of the glass jars.
   
6. Groups place a square of diaper of sample A in one jar of water and B in the other.
   
7. Watch each jar carefully. After 3 minutes record observations on lab sheet.
   
8. Carefully, have a group member pour excess water from one glass jar into the empty graduated cylinder. Record this amount on the lab sheet and subtract from 100 ml to get the percent of water absorbed. Repeat with other jar.
   
9. Record which diaper sample absorbed more water, then dispose of wet diaper samples.
   
10. Prepare a 10% saline solution using 10g or 10 ml of sodium chloride in each jar and 10% tap water in each jar and repeat steps # 5-9.
    
11. Groups determine which diaper they would most want their baby sibling to wear.

1. Lead the class in a whole group discussion trying to determine which diaper absorbs water the best. Obtain tap water results from each group, then plot results on a graph for all to see. Repeat with the saline solution experiment.
   
2. Discuss what variables might make some group results different than others even when the same sample was used.
   
3. Orally, have groups share what their group did cooperatively that ` helped them complete their lab sheet effectively. Ask if they would do something differently next time.
   
4. Brainstorm other uses for "super slurper" with the class.
   
5. Discuss the impact of these polymers on the environment and explain the use of polyacrylamide in agriculture.

Extensions/Integrations:

1. Language Arts: a) Have students write a commercial for a baby diaper based on the results of their experiments. Include persuasivelanguage to sell their diaper. b) Organize a classroom debate on the pros and cons of super-absorber
   
2. Math: Prepare additional problems requiring percentage calculations. Students could write their own word problems about similar experiments. Increase difficulty level by basing results on 200 ml of water, etc. Water temperatures could also be compared.
   
3. Environmental Education: a) Bury pieces of the diapers in a bag of soil or a whole diaper outside under the ground for long term study. Check it from time to time to see if it has biodegraded. Discuss environmental implications after viewing. b) Try planting seeds or plant clippings in swollen diaper pieces or in sodium polyacrylamide or sodium polyacrylamide-enhanced soil. Call J.R.M. Chemical Company to order this product at their special educator cost at 1-800-962- 4010. SOILMOIST, J.R.M.'s polymer enhanced soil product is available at local nurseries, but itsswellability is not very dramatic.
   
4. Physical/Earth Science: Cover jars containing swollen diaper pieces with plastic wrap to observe EVAPORATION and DEHYDRATION.

DATE____________________

GROUP LAB SHEET: HERE, YOU TAKE THE BABY! ICK!

Problem: Your baby brother or sister is sitting on your lap. Which diaper would you refer he/she wear?

Hypothesis: We would like our younger brothers or sisters to wear

diaper_____ because________________________________________________________

Materials: 2 glass jars, 1 graduated cylinder, 4 diaper squares (2 of each brand), sodium chloride, tap water.

Procedure:

1. Write down observations about dry diapers:

Sample A:

Sample B:

2. Measure 100 ml of tap water into each of the glass jars.

3. Place a diaper square sample A in one jar, a sample B in the other jar.

4. Write down observations about diapers in tap water after 3 minutes.

Sample A:

Sample B:

5. Carefully pour excess water from the glass jar with sample A into the empty graduated cylinder. Record this amount in the number sentence below. Empty the cylinder, then, repeat with the other jar.

Sample A: 100 ml - __________ = ________%

Sample B: 100ml - __________ = ________%

Which sample absorbed the most water?_______________________

6. Measure the amount of salt water the diaper samples absorbed the

same way and record the results below.

Sample A: 100 ml - __________ = _________%

Sample B: 100 ml - __________ = _________%

Which sample absorbed the most saline water?__________________

7. Conclusions: We would rather our baby brother or sister wear

diaper sample diaper ______ because ____________________________

EXPERIMENT 2: NAME THAT SUBSTANCE!

Materials for each group:

6 (35 mm) camera film cases filled with 6 different substances from the Table of Physical Properties Chart (Choose at least 2 substances which can not be identified just by color or appearance. Hint: Baking powder displays a noticeably different reaction to hot vs. cold water and would be a good all-around choice. Salt and refined sugar are a challenging duo as well.

1 plastic spoon

2 clear containers to mix substances in water (source of hot and cold water; WARNING: do not use scalding hot water)

1 pair of goggles for students handling substances

Procedure:

1. Divide class into groups of six.
   
2. Assign cooperative jobs: Leader, Reader, Recorder, Custodian, Encourager and Gatekeeper.
   
3. Explain experiment and review lab sheets. List the names of the substances provided on the chalk board.
   
4. Group members make observations by noting the color and appearance of each substance. Should the group agree that a substance can be identified based on these criteria they may complete the grid on the lab sheet.
   
5. Next, taking turns the groups will explore the physical characteristics of each unidentified substance, by observing its reaction to hot and cold water.
   
6. Based on the results in #5, groups will complete the identification grid on the lab sheet.

Reflective Questioning:

1. Lead the class in a whole group discussion by having the recorder from each groupwrite their final results on the board.
   
2. Share the real identities of each substance and have groups orally share their techniques for identifying the substances.
   
3. Finally, have groups share positive experiences about working in a group, and what they might change the next time when working in a group.

Extensions/Integrations:

1. Math: Students create other grids similar to the Table of PhysicalProperties such as: How to tell shoes apart, different types of sandwiches, pens, animals, etc.
   
2. Social Studies: Have groups list the different geographical characteristics andtemperatures of states in the U.S. Then, have other groups try to identify the state described.
   
3. Language Arts: Divide students into pairs and provide each pair with an object to describe physically with as many adjectives as possible. The three groups with the most adjectives that are reasonable gets to keep the object!

DATE_____________________

GROUP LAB SHEET: NAME THAT SUBSTANCE

Problem:
You're cleaning the kitchen cabinets for your mom or dad when suddenly six containers crash to the floor! The containers open up and their contents come rushing out. How will you identify what each substance is? No tasting!!!

Materials:
6 substances, 1 plastic spoon, 2 clear containers for mixing, 2 hand lenses, hot and cold water, goggles for student handling substance.

Procedure:

1. Taking turns, try to identify substances by color only using the TABLE OF PHYSICAL PROPERTIES and the list of substances on the board.
   
2. Continue using the TABLE OF PHYSICAL PROPERTIES to identify each substance using your hand lenses and water solubility tests when necessary.
   
3. Complete the chart below, listing the properties which helped you decide the name of each substance.
   
   

   SUBSTANCE NUMBER	SUBSTANCE NAME	PHYSICAL PROPERTY
   #1
   #2
   #3
   #4
   #5
   #6

   
   
   
4. When done, CHECK your answers with the properties listed for each item on the TABLE OF PHYSICAL PROPERTIES. Clean-up and brainstorm other powders we could. have used.