Biology-Chemistry High School SMILE Meeting
21 November 2000
Notes Prepared by Porter Johnson

Christine Etapa [Gunsaulus Academy]
brought us into the world of slime. We made three different kinds of slime [silly putty] following the recipes given out. In reality we were making polymers and comparing each of the polymers we made.

She led us through the first recipe, [2 grams of Borax, 70 ml of water, and 40 ml of white glue] so that there would be no confusion. To our amazement, right in front or our eyes our mixtures thickened and jelled into polymers. When we played with our first creation [like putty] it was soft yet pliable and able to bounce. It was able to "run", but easily cleaned up.

When trying the second recipe [75 ml white glue, 45 ml water, and 1 to 30 grams of talcum powder, and 1 gram of borax, and a few drops of food coloring], the mixture was more solid, like Play Dough or clay.

The third recipe [75 ml glue, 45 ml water, 1 to 30 grams cornstarch, 1 gram Borax, and a few drops of food coloring] was more adhesive than the rest. It was also quite "runny".

The recipes for the second and third could be adjusted to vary the consistency, and to compare the results.

For more details see these websites:

Playing with Polymers: http://www.reachoutmichigan.org/funexperiments/agesubject/lessons/polymer.html.
Making Polymers: http://www.kids.union.edu/makingPolymers.htm .
Making Superballs: http://techsupt.winbatch.com/webcgi/webbatch.exe?techsupt/nffunsupt.web+Chemistry~Experiments+Making~a~Superball.txt
The Macrogalleria; a cyberwonderland of polymer fun: http://www.pslc.ws/macrog/index.htm.
Minilabs Slime Science: http://www.hobbylinc.com/htm/sly/sly2021.htm

Pat Riley [Lincoln Park HS] Ionic bonding versus Covalent Bonding
Materials

1 slide label [ A B C D ]
4 cups
4 spoons
beaker and graduated cylinder
conductivity tester

We placed a small amount of substance A on the slide in its respective location. then we repeated this for substances B, C, and D. We then carefully placed the slide on a hot plate. We placed a thermometer on a clear part of the glass, and turned on the heat. We then waited and watched to see which substance melted first:

Sample A melted first at about 30 ^oC
Sample B stayed the same
Sample C started to shrink and melt at about 70 ^oC
Sample D started to crystallize and clump and changed color

Ionic compounds are usually hard, brittle, and water soluble, with high melting points. They can conduct electricity when dissolved in water. Molecular compounds can be soft, hard, or flexible; are usually less water soluble; have lower melting points; and cannot conduct electricity when dissolved in water. So, we guess that A and C were covalent, whereas B and D were ionic.

Then we performed a solubility test in water for each of the samples

A: Insoluble B: Soluble C: Soluble D: Soluble Conductivity test: we inserted an electrode to see if they conducted electricity: A: No B: Yes C: Yes D: No In actuality we had the following materials: A: Carnauba Wax B: Table Salt C: Sugar D: Epsom Salts [MgSO₄]

What is going to happen next?!
DON'T MISS IT!
Notes taken by Pam Moy