wg48
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chemiluminescence and an oscillating reaction
I imagine it already been done or tried to be but if not we should try to couple a chemiluminescence reaction with an oscillating reaction to flash
the light on and off.
For a supper neat effect couple it to two chemiluminescence reactions that produce different colours so the light varies between the two colors.
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careysub
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It doesn't oscillate exactly, but Volume 1 of Shakhashiri's Chemical Demonstrations has a "Two-Color Chemiluminescent Clock Reaction" (red,
then blue) with the following reagents:
luminol
sodium hydroxide
potassium carbonate
pyrogallol (pyrogallic acid, 1,23-trihydroxybenzene)
40% formaldehyde
30% H2O2
Gallic acid can probably be substituted for pyrogallol.
Procedure:
Wearing gloves, measure 40 mL of distilled water into a 250 mL beaker. Add 0.8 g of sodium hydroxide and dissolve. Add 0.005 g of luminol, 25 g of
potassium carbonate, and 1.0 g of pyrogallol, Stir to dissolve. Add 10 mL of 40% formaldehyde. Pour the solution into a 1 L beaker, and place the
beaker in a 2 L beaker or shallow pan.
To perform the demonstration, dim the room lights and add 30 mL of 30% H2O2 ro the 1 L beaker. Sitrring is not necessary. The reaction mixture glows
dull red for several seconds, followed by extensive foaming and the solution becoming hot, and then bright blue for a few more seconds.
It is based on two sequential oxidation reactions, first we get the singlet oxygen glow from oxiidizing pyrogallol and formaldehyde by alkaline H2O2,
and then the oxidation of luminol apparently by free radicals produced by the pyrolgallol oxidation. CO2, H2, and O2 are all evolved to produce the
foaming.
The actual reaction sequence, at the time of writing, 1983, was not well understood.
Volume 2, however does have an oscillating chemoluminescent reaction: Photofluorescent Cerium-catalyzed Bromate-Malonic Acid Reaction (A
Modified Belousov-Zhabotinsky Reaction).
This requires:
Potassium bromate (13 g) or sodium bromate (12 g)
Potassium bromide (0.3 g) or sodium bromide (0.26 g)
Malonic acid (16 g)
Tris(bipyridine) ruthenium(II) chloride (0.045 g)
6M H2SO4 (150 mL)
Cerium(IV) ammonium nitrate (0.38 g)
Distilled water (600 mL)
and a UV light (it does not glow by itself)
The instructions are much more complicated, and I am not up to typing them out right now. Maybe I can make and post a PDF of the entire procedure and
discussion later (5 pages).
The oscillation is between a bright orange fluorescence and a dark state.
[Edited on 28-11-2016 by careysub]
About that which we cannot speak, we must remain silent.
-Wittgenstein
Some things can never be spoken
Some things cannot be pronounced
That word does not exist in any language
It will never be uttered by a human mouth
- The Talking Heads
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Neme
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I don't have currently time to read whole text but do you mean something like this?
Attachment: luminiskujici oscilace.pdf (74kB)
This file has been downloaded 384 times
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wg48
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Those last two posts give me the urge to synthesis some luminol. Nerd Rage has an OTC route and no cyanide required like the malic acid.
Its £13 for one gram on ebay or £30 for 25g, perhaps a xmas present to myself LOL.
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Neme
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I have been doing the experiment in pdf I attached, it works pretty fine. It starts glowing for few seconds every two minutes (sometimes little bit
longer).
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DJF90
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There was one demonstrated on LabPhoto a few weeks/months back.
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