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      Introduction

      Today's activity is very straightforward. We're going to play with sulfur. You should have a lot of fun doing this. A molecule of rhombic sulfur is made of eight sulfur atoms arranged in a ring. When rhombic sulfur is heated above 180°C and is quickly cooled, the rings open and join together to form long linear chains, like this:

      polymerization of rhombic sulfur

      This chemical reaction is, of course, a polymerization. The molecular structure of the polymer produced consists simply of a long chain of sulfur atoms. This is the polymer we're going to make today.

      Materials

      To do this activity, this is what you'll need:

      1. Rhombic sulfur (also called powdered sulfur or flowers of sulfur)
      2. Test tubes ~10 mm × 100 mm
      3. Bunsen burner
      4. 100-250 ml beaker
      5. Water
      6. Zip lock sandwich bags
      7. Spatula
      8. Test tube tongs

      Procedure

      1. Use the spatula to place the sulfur in your test tube, until the tube is about 90% full.

      2. Fill the beaker with water.

      3. Light the Bunsen burner.

      4. Hold the test tube with the test tube tongs, and then heat the bottom of the tube in the flame. Heat it by placing the bottom end of the tube in the flame, and keep the test tube moving around in the flame to ensure even heating.

          WARNING! Do not hold the test tube with your hands when you do this. If you do, you WILL burn your hands.

          WARNING! Always point the open end of the test tube AWAY from yourself and others. The contents may splatter out and cause burns.

          WARNING! Do not pass the mouth of the tube through the flame. This may cause the sulfur vapors to ignite and burn. Burning produces sulfur dioxide, a gas that is poisonous and stinks.

      5. The sulfur will first melt, becoming a reddish amber color. After continued heating, it will turn black and get very thick. When it has turned black and become thick, quickly pour the contents of the test tube into the ice water.

      6. Use tweezers to remove the material that forms in the beaker.

      7. After investigating the material, feeling it, and studying it, put your material in a zip lock sandwich bag and seal it up.

      8. The next day, observe your material. What is it like now?

      Questions

      Answer these questions when you've finished the activity.

      1. What is your material like?

      2. What happens to your material after several days?

      3. Do you think this material would be a useful product?

      4. In this reaction you turned rhombic sulfur into polymeric sulfur. The molecules of the both the reactant and the product are made of atoms of the same element. Why then do they behave differently and have different properties?

      References

        Bacon, R.F., and Fanelli, R. Journal of the American Chemical Society, 1943, 65, 639.

        Meyer, K.H. Natural and Synthetic High Polymers. New York: Interscience, 1950.

        Sorensen, Wayne R., and Campbell, Tod W. Preparative Methods of Polymer Chemistry. New York: Interscience, 1961.

        Tobolsky, A.V., and Eisenberg, A. Journal of the American Chemical Society, 1959, 81, 780.

        Watt, Shirley, ed. Polymer Chemistry, Rev. Ed.. Arlington, VA: National Science Teachers Association, 1997, pp 201ö202.

      Copyright ©2001 The Chemical Heritage Foundation