Belousov-Zhabotinsky oscillating reaction

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SUMMARY

The discussion centers on the Belousov-Zhabotinsky oscillating reaction, specifically the challenges faced by a physics student in replicating the experiment. Key reactants mentioned include sulfuric acid (H2SO4) at 1.5M, sodium bromate (NaBrO3) at 0.08M, malonic acid (CH2(COOH)2) at 0.002M, and ceric sulfate (Ce(SO4)2) at 0.1M. Recommendations include increasing the concentration of malonic acid to 0.2-0.3M and using ceric ammonium nitrate instead of ceric sulfate. Continuous stirring for at least one minute is essential to observe the expected color oscillations.

PREREQUISITES
  • Understanding of chemical kinetics and reaction mechanisms
  • Familiarity with the Belousov-Zhabotinsky reaction
  • Knowledge of molarity and solution preparation
  • Experience with laboratory mixing techniques, including the use of magnetic stirrers
NEXT STEPS
  • Research the chemical properties and roles of ceric ammonium nitrate in oscillating reactions
  • Learn about the effects of reactant concentration on the Belousov-Zhabotinsky reaction
  • Investigate the use of magnetic stirrers for enhancing reaction outcomes
  • Explore troubleshooting techniques for chemical experiments in oscillating reactions
USEFUL FOR

Chemistry students, experimental physicists, and researchers interested in chemical oscillations and reaction dynamics will benefit from this discussion.

Feynmanfan
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Here's a physics student trying to perform the Belousov experiment, that is the chemical clock that changes its color from red to blue and viceversa.

I've been able to "borrow" the following reactants:

H2S04(sulfuric acid) 1,5M
NaBr03(sodium bromate) 0.08M
CH2(COOH)2(malonic acid) 0.002M
Ce(SO4)2 0.1M
ferroin 0.0003.M

I've tried mixing them but I've seen no oscillations. The original recipe says that Ce2(SO4)3 should be used (Ce3+//Ce4+ is what oscillates). What do you suggest I should do? In what order do I mix the reactants? Is this a bad recipe?
Thanks for your help!
 
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1. I think your malonic acid is too dilute. I recommend 0.2 to 0.3M acid.

2. The order of mixing should not matter.

3. I think your Ce(SO4)2 is too concentrated. I would use something like 0.002M Ce(4+) solution. Or did you just switch the concentrations of the acid and ceric sulfate when you typed it here ?

4. If switching the concentrations doesn't help (or you just mistyped it here), you could try ceric ammonium nitrate instead of ceric sulfate.

5. What color do you see when you prepare the solution ?

6. The typical period of oscillations for the specified concentrations is of order a minute. So, you need to have the solution be stirred continuously for at least that long to see a color change. A better idea (once you have a working solution, at least) is to use a magnetic stirrer.
 

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