Fluorescent oscillating reaction

A mixture of three solutions periodically changes color and glows in UV

Scientific name: Fluorescent oscillating reaction with ruthenium and cerium ions

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fluorescent Briggs Rauscher Reaction

Fluorescent Oscillating Reaction Demonstration Kit - Flinn Scientific

Safety

Wear eye protection and lab gloves.

Avoid contact with acids with skin.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

Br2 + CH2(COOH)2 → BrCH(COOH)2 + Br- + H+

BrO3- + 12H+ + 10 Ce3+ → Br2 + 6H2O + 10Ce4+

Ce4+ + Ru2+ → Ce3+ + Ru3+

Step-by-step instruction

  1. Mix 16 g of malonic acid, 0.30 g of potassium bromide and 300 ml of water. It is solution A.
  2. Mix 13 g of potassium bromate and 300 ml of water. It is solution B.
  3. Mix 0.045 g of tris(bipyridine)ruthenium(II) chloride hexahydrate, 0.38 g of cerium(IV) nitrate and 150 ml of 6M sulfuric acid. It is solution C.
  4. Put a magnetic stir bar and pour solutions A and B into a 1l beaker, place the beaker on a magnetic stirrer and start to stir.
  5. Pour solution C into the beaker.
  6. Carefully lower a UV lamp into the beaker and secure it so that the liquid does not contact with the socket of the lamp.
  7. Make it dark and switch on the UV lamp. There are oscillations between bright and dark fluorescent orange in the solution.

Scientific background

This reaction is a modification of the Belousov-Zhabotinsky (BZ) reaction, and has the same mechanism. But there is an important additional reaction in this modification - the Ce4+ ions react with the Ru2+ ions producing the Ce3+ and the Ru3+ ions. The Ru3+ ions fluoresce in UV whereas the Ru2+ ions don't.

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Published on 28 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst