Chemiluminescence - the oxidation of luminol
Light without heat
Chemiluminescence is a 'fascinating phenomenon where a chemical reaction produces light without heat'. The oxidation of luminol is a good example.
The oxidation of luminol
Dissolving luminol (3-aminophthalhydrazide or 5-amino-2,3-dihydro-1,4-phthalazinedione) in a base abstracts the protons from the two cyclic nitrogen atoms, resulting in a intermediate which is readily oxidised by hydrogen peroxide or household bleach (sodium chlorate(I)) to an excited intermediate, the decay of which to a lower energy level is responsible for the emission of a photon of light.1
Having experimented with several different methods from a variety of sources to demonstrate chemiluminescence, often with disappointing results, I found the following method, by Declan Fleming of the University of Bristol,2 to work effectively in a blacked out classroom setting. This method results in a relatively rapid rate of reaction, producing bright chemiluminescence albeit on a short timescale.
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