Sharon Endebak

Super Ball

 

Science Concept:

Sodium silicate reacts with ethanol forming a polymer that has rubber properties.

Materials:

sodium silicate solution (40%)

ethanol

food coloring

stirring rod

100 mL graduated cylinder

400 mL beaker

10 mL graduated cylinder

latex gloves

paper towels

Directions:

1. Measure 20 mL of sodium silicate solution in the 100 mL graduated cylinder.

2. Pour the sodium silicate solution into the 400 mL beaker.

3. Add food coloring, if desired, to the sodium silicate solution.

4. Measure 5 mL of ethanol in the 10 mL graduated cylinder.

5. Add the ethanol to the sodium silicate solution.

6. Stir the solutions quickly as the solid begins to form.

7. When mixture is solid, remove from beaker using latex gloves. If the mixture

still has not formed a solid, add 5 mL more of ethanol.

8. Start molding the mixture into a ball, using paper towels to dry it as you work.

Be careful not to mold it too hard as it will crumble.

Introduction:

Do you want a toy to play with while you watch the rest of these demonstrations? Well, then you will love this demonstration.

Explanation:

In this demo we will concentrate on the element silicon. Silicon is found in sand and is a major element found in computer chips. The liquids solution of Sodium silicate is already in the form polymer. The silicate is alternating atoms of silicon and oxygen. These long chains are called the polymers. When the ethanol is added, it bridges and connects the chains by cross-linking them. The analogy of a chain-link fence is a good picture of the idea of chains that are cross linked. That is what the ethanol and the silicate are doing to form this super ball.

Safety:

Use latex gloves to keep hands clean while working with it when it is wet.

 

Disposal:

If there is any excess of the rubber ball, it must be disposed of in the garbage.

Reference:

Borgford, C, and Sommerlin, L, Chemical Activities, American Chemical Society, 1988,p. 89