[limpet chicken]

I had something strange just happen.

I was curious about the chemiluminescence effect caused by passing chlorine through H2O2 solutions, causing the evolution of singlet oxygen, and yielding ClO2.

So I decided just out of curiosity, to try with iodine, as it was convenient.

Roughly 5-6 of OTC 9% hydrogen peroxide, containing phosphoric acid as stabiliser, and phenacetin, were put into an aluminium foil pie case, of the kind used for small snacks, and a few mg of iodine was added, just a tiny flake or two, I would estimate perhaps 6-7mg at the most, and on seeing nothing, the peroxide was heated from below with a direct flame.

Rapid boiling was evident, along with near instant formation of a dark indigo-blue color, however, the blue liquid was alowed to boil dry, and on full evaporation, a dark blue compound was deposited on the aluminium surface, which then detonated with a sharp crack, blowing a small hole through the pie case, depositing brown residue and releasing a plume of iodine vapour into the air.

I suspect the triiodide ion played some role in the makeup of the dark compound, as triiodide is the only dark blue state of iodine that I know of, but I can't figure for the life of me why it exploded

I looked it up and found nothing on halogen peroxides of any sort, only things I can think of, are peroxidation of residual fats on the surface of the pie case, or a peroxyacid forming from the phosphoric acid PH buffer attacking the fat residues and exploding, with formation of the triiodide ion merely being produced outside of the explosive reaction itself and playing no part.

This isn't asking how to make explosives or anything, but I am left wondering why in fact, an explosion occured at all.

[jdurg]

Anytime you have iodine and aluminum in contact with each other, heating it up isn't a good idea.  It will cause the iodine to readily vaporize and react quite exothermically with the aluminum.

[Mitch]

You added phenacetin to hydrogen peroxide!  

NEVER EVER MIX ETHERS WITH PEROXIDES AND ALLOW IT TO GOTO DRYNESS!!!!!!!!!!

You made an organic peroxide, which are quite unstable. I hope this serves as a warning to others.

NEVER EVER MIX ETHERS WITH PEROXIDES AND ALLOW IT TO GOTO DRYNESS!!!!!!!!!!

So the take home message of today is...

NEVER EVER MIX ETHERS WITH PEROXIDES AND ALLOW IT TO GOTO DRYNESS!!!!!!!!!!

[limpet chicken]

I didn't add the phenacetin, for some strange reason, in the UK, the commonly available brands of H2O2 come with phenacetin and phosphoric acid already present, which I think is quite a retarded thing to sell, for that exact reason (peroxidation), I guess they don't expect people to boil it or use it for chemistry experiments though