Chemical traffic light experiment

After shaking the bottle, it is place on the table for the chemicals to settle. When the bottle is shaken the color turns from yellow to green. After couple of minutes the color turns red and eventually turns back to yellow. This chemical reaction is sped up to 400%.

The chemical traffic light is the reaction of the changing in color of the solution which also related to the blue bottle experiment. One of the early formula consists of glucose, sodium hydroxide, indigo carmine, and water. Another formula consists of indigo carmine, dye, ascorbic acid (Vitamin C), sodium bicarbonate, sodium chloride, copper(II) sulfate, sodium hydroxide and water.[1] By doing so, chemical waste and the level of corrosive is reduced. The amount of solid chemicals dissolved in the experiment could be reduced from 60 grams to 6 grams. And the pH could be lowered from 13 to 3 which is easier to neutralize the pH to 7 by adding baking soda before disposal.[2] Also, it is safer and the reactions also occur faster and easier to perform.

At first, all chemicals were added together and the color appeared yellow. After shaking was done, the color turned green and then changed to red after it was left untouched. When further observed, the color turned back to yellow, which is why the solution is called the chemical traffic light. This reaction can be repeated many times but it need to add more oxygen or indigo carmine.

Chemical reaction

When the solution is shaken, oxygen dissolves in the solution and oxidizes indigo carmine. Solution becomes red if a small amount of oxygen is dissolved, and green if all of indigo carmine is oxidized.[3]

See also

References

  1. ↑ Rajchakit, Urawadee; Limpanuparb, Taweetham (2015-10-16). "Greening the Traffic Light: Air Oxidation of Vitamin C Catalyzed by Indicators". Journal of Chemical Education. doi:10.1021/acs.jchemed.5b00630.
  2. ↑ Wellman, Whitney E.; Noble, Mark E.; Healy, Tom (2003-05-01). "Greening the Blue Bottle". Journal of Chemical Education 80 (5). doi:10.1021/ed080p537.
  3. ↑ "Chemical Traffic Light". MEL Science.
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