Purpose
To illustrate the absorbing power of the polymer found in diapers.
Materials
- Acrylic sodium salt polymer (A.S.A.P.), diaper powder, potassium polyacrylate
- Styrofoam cup
- Bottle of water
- Piece of cardboard
- Read the MSDS/WHMIS sheet for acrylic sodium salt polymer
- Wear chemical safety glasses
- Water/powder may fall out of cup
Procedure
- Cover the bottom of a white styrofoam cup with a thin layer of ASAP powder prior to class.
- Show the class that the cup is empty by tilting it towards them. (The diaper powder is white and as a result cannot be seen.)
- Pour a small amount of the bottled water (~10 mL) into the cup.
- Glance in the cup to check if all the powder was wetted by water. If not, add some more water.
- Place a piece of cardboard over the top of the cup and then invert the cup.
- Place the cup over a student head and then remove the cardboard.
- Allow the student to look up and then reveal the empty cup to the class.
- The addition of water can be repeated several times, but be careful near the end or someone may get wet.
Results
The diaper powder turns to a damp white gel which remains stuck to the bottom of the cup upon addition of water.
Follow-up Teaching Notes
Diaper powder absorbs ~900 times its own mass of water.
Connections
Polymers
Extension
Have students design a lab to determine the absorbing capacity of the powder and/or what conditions affect absorbance.
Disposal/Clean-up
The cup and contents can be disposed of in the garbage.
