Re: experiments concerning chemical chain reactions.

What you saw was a "clock reaction", probably the iodine-clock reaction. Even more interesting are oscillating reactions. Unfortunately, these reactions do not use household chemicals, except 3% hydrogen peroxide. Therefore, you won’t be able to run these experiments without assistance from a teacher with access to these chemicals. You will also need to be very careful with some of the chemicals, especially the sulfuric acid. You will want to wear rubber gloves and goggles.

Recipe for Briggs-Rauscher Oscillating Reaction:

Solution (1) is just drugstore (3%) hydrogen peroxide.

Solution (2) is prepared by placing 29 g of potassium iodate (KIO3) (26 g of NaIO3 can be substituted) and about 400 mL of distilled water in a 1 liter beaker. Add 8.6 mL of 6.0 M H2SO4. (To prepare a stock solution of 6.0 M sulfuric acid, carefully pour 330 mL of concentrated [18 M] sulfuric acid into 500 mL of distilled water and dilute to 1.0 L.) Stir the solution until the iodate dissolves (this may require some heating -- sodium iodate will dissolve more readily).

Solution (3) is prepared by dissolving 10.4 g of malonic acid and 2.2 g of manganese (II) sulfate monohydrate (MnSO4 o H2O) in about 400 mL of distilled water in another 1 L beaker. In a 100 mL beaker, heat 50 mL of distilled water to boiling. In a 50 mL beaker mix 0.2 g of soluble starch with about 5 mL of distilled water and stir the mixture to form a slurry. Pour the slurry into the boiling water and continue heating and stirring the mixture until the starch is dissolved. (NB: This step is crucial, because if the starch is not dissolved, the oscillations will not be visible.) Pour the starch solution into the malonic acid/manganese sulfate solution. Dilute it to 500 mL.

Pour equal volumes of (2) and (3) into a beaker equipped with a magnetic stir bar. (The demonstration can be performed without mixing, but the transitions will not be as sharp as with mixing.) Add a volume of (1) equal to the sum of (2) and (3).

Useful references:

Briggs, T. S.; Rauscher, W. C. "An Oscillating Iodine Clock Reaction,"J. Chem. Ed. 1973, 50, 496.

Epstein, I. R.; Pojman, J. A. An Introduction to Nonlinear Chemical Dynamics: Oscillations, Waves, Patterns and Chaos; Oxford University Press: New York, 1998.

Soltzberg, L. J. "Self-Organization in Chemistry - The Larger Context,"J. Chem. Ed. 1989, 66, 187.

Gleick, J. Chaos: Making a New Science; Viking: New York, 1987.

Shakhashiri, B. Z. Chemical Demonstrations: A Handbook for Teachers. Volume 2; University of Wisconsin Press: Madison, 1985.

Useful www sites:

http://www.pojman.com http:// heracles.chem.wvu.edu/new/default.htm