Lab #8 - Making a Super Ball
Introduction: Two common liquids are mixed, and the reaction makes a solid that has properties of rubber. The solid is a polymer. Chemists identify polymers as long chains in which molecules have linked up and twisted around each other, much like the paper chains people make for Christmas trees. Nylon, polyethylene, wood (cellulose), proteins, and most plastics and rubbers are all polymers of particular molecules.
Materials: 20 mL sodium silicate (water glass solution), 5-10 mL ethyl alcohol, Stir stick, paper towels, paper cup for mixing of solution.
Safety Note: Students should wear goggles and plastic disposable gloves
Reaction: Silicon is a very
interesting type of atom. Find its position on the periodic table
of the elements. Like carbon, silicon makes four chemical bonds and
can branch out in that many directions to make long chains. In sodium
silicate, the silicon atom is bonded to 4 oxygen atoms and is not linked in
any chains. The ethyl alcohol molecule is very simple and has just
two carbon atoms. When sodium silicate and ethyl alcohol are put together,
the silicate particles begin to link up with each other to form long
chains as the ethyl groups (sometimes shown as "R") replace oxygen atoms
in the silicate ion. Some become cross-linked between chains.
Water molecules are by-products of the formation of the polymerization bond.