High School Biology-Chemistry SMILE Meeting
11 March 2003
Notes Prepared by Porter Johnson

Barbara Lorde [Attucks Elementary School, science; grades 3-8]      Making a Plastic Toy
Barbara warmed one cup [250 ml] of milk in a saucepan for a few minutes, and slowly stirred in 5 tablespoons [75 ml] of vinegar.  The casein [a milk protein] and fats separated out, because the drop in pH (increased acidity) caused them to become insoluble. A rubbery mass was initially formed, but eventually it began to harden into a plastic consistency.  She then added food coloring to the casein during the class, to make it more interesting.  This casein-fat mass can also be squeezed or placed in a mold to produce a "toy" after hardening. She also suggested that you could bring in ratios and proportions in a practical context, as well as convert into metric units.  An interesting Chemistry lesson, as well as  ... 

... artistic, Barbara!

Tyrethis Penrice [McKinley Academy]      Soft Water vs Hard Water
Tyrethis called our attention to the following websites on Soft Water:  http://pasture.ecn.purdue.edu/~agenhtml/agen521/epadir/grndwtr/softened.html and http://scifun.chem.wisc.edu/HOMEEXPTS/SOFTWATR.html. Then we performed the experiment described in the second website, making our own hard water by mixing 1 teaspoon [5 ml] of Epsom Salts [MgSO4] to 1 cup [250 ml] of distilled water.  We added several drops of liquid dish detergent to this mixture, as well as to an equal amount of distilled water.  We were not able to produce as much suds with the artificially hardened water, in comparison with distilled water.  Still, the difference was not as great as we had expected.  Why?

    Soft Water VS Hard Water
  1. Soft Water (Rainwater): Forms suds easily. No scum or film present. Presence of Na+.
  2. Hard Water ( Ca++ or Mg++ present): Prevents lathering of soap or shampoo. Produces soap scum on surfaces. Clogs pores and coats hair on skin. Residue serves as breeding ground for bacteria. Formation of a hard scale, which can clog plumbing and build up in water heaters, leading to an increase in utility bills and appliance failure.
  3. Methods of treating hard water:

Good Chemistry for everyday life!  Thanks, Tyrethis!

Chris Clausing [Bloom Trail HS]      Inorganic Nomenclature
Chris made a Powerpoint™ presentation using the interactive CD- ROM Inorganic Nomenclature, which can be used by students on their own computers, and which tabulates scores.  The CD-ROM was obtained from the Johnson County Community College in Kansas.  For more information contact Donnie Byers: donbyers@jccc.net.

Chris modified the making compounds section of the CD by making game pieces out of cardboard to represent ions:
 Monovalent, divalent, and trivalent positive and negative ions are represented by pieces, as shown, and compounds are made by fitting the pieces together.  For example, the assembly dissociation of H20 is represented as follows:
Chris has also developed a program called Chemistry in the Schools [CITS], in which he teaches high school students who, in turn, teach 4th and 5th graders. They use exercises such as freezing a banana in liquid nitrogen, and then using the frozen banana to drive a nail into wood. For more information on this program, contact Chris.

Terrific stuff, Chris!

Barbara Pawela [May School, retired]      Strong Ice:  chbi1700.htm
Barbara made a presentation based upon a lesson that she developed in SMILE in Summer 2000, which consisted of the following activities:

  1. She placed various canned soft drinks inside Ziploc™ bags, put them in the freezer for several days, and brought them to class.  The cans had failed in various ways, with punch-through at the top, or large deformation.  She did the same experiment with filled glass and plastic bottles.  The glass bottles shattered, whereas the plastic bottles either shattered or were greatly deformed.  We concluded that there is power in the expansion of water when frozen into ice.  She also froze water in a metal can with a lid --- the lid being held in place with pencils and heavy tape.  The pencil didn't break, but it did bend so much that the lid was pushed off.
  2. The second activity involved mixing INSTANTS expandable capsules into a glass half-filled with water, and observing the expansion of the sponge toy as fluid was absorbed into it..
  3. The third activity involved putting a water-filled vial with a tightened screw cap into a salt-ice mixture.  After about 20 minutes the vial cracked, because ice had begun to form inside the vial.
  4. Finally, Barbara placed a Nickel on top of an ice cube, and let it sit for a few minutes.  We found that the Nickel had become stuck to the ice, and had to be pried off.  Why?

Fascinating, Barbara!

Scheduled Future Presentations:

Notes taken by Ben Stark.