Belousov-Zhabotinsky Oscillating Reaction
Recipe
Equipment
Balance capable of weighing 100 g.
25 mL graduated cylinder
100 mL graduated cylinder
250 mL graduated cylinder
Magnetic Stirring Hot Plate
1-1500 mL Pyrex beaker
1-1000 mL Pyrex beaker
4 - 500 mL Pyrex beaker
1- 250 mL Pyrex beaker
1 petri dish
1 overhead projector
Solution A
800 mL water
60 gm. NaBrO3
24 mL. conc. H2SO4
Solution B
25 g. Malonic acid
250 mL. water
Solution C
0.5 g. o-phenanthroline
1.0 g. Ferrous ammonium sulfate.6H2O
100 mL. water
Mix together:
180 mL. Solution A
130 mL. water
30 mL. Solution B
10 mL. Solution C
This gives a solution that is mostly red but flashes blue at 17-19 sec.
intervals at 25C for approximately one hour and 15 min. if stirred
continuously.
The reaction should be carried out at a higher temperature in another experiment.
Some Concentrations for Common Reagents
Tolerances in Commen Chemical Measurements
A. T. Winfree's Recipe
- 67mL water + 2mL conc. sulfuric acid + 5g sodium bromate are mixed to form about 70mL of solution.
- Take 6mL of this solution and add 1mL Malonic acid solution (formed from 1g/10 mL water). Add 0.5mL NaBr (1g in 10mL).
- After Br color has gone add 1mL of 25mM phenanthroline ferrous sulfate and a drop of Triton X-100 surfactant (1 g in 1000mL) to spread solution.
Note: the solutions should be Cl- free. Use distilled water. Chloride ion knocks out the reaction (a later experiment might be to add a certain amount to observe what happens!).
Leaving out 1/2 the H2SO4 suppresses spontaneous oscillation.
Note: Use very clean petri dishes since a speck of dirt or a scratch will act as nuclei for CO2 bubbles and as pacemaker nuclei causing a profusion of waves.
A.T. Winfree, The Geometry of Biological Time, Springer-Verlag, N.Y., 1980, Chapter 13, page 301.
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