Sciencemadness Discussion Board

Insoluble oxidising agent

froot - 19-1-2004 at 00:57

I cannot seem to find any, would they exist? Basically I would like to try a few experiments with insoluble burning mixtures, the main application being for fuses that could burn underwater. I was thinking along the lines af a thick mouldable gel-like mixture that I would set in a wire braid from a piece of coax cable. This is just to describe the application to give you a better idea of what could work.
I was wondering if anyone had any ideas for the insoluble burning mixture, not making fuses!

chemoleo - 19-1-2004 at 08:59

Try KClO3 or KClO4 (which are virtually insoluble) with sulphur (also insoluble). Mix it and add a thin solution of polystyrene in acetone (any yoghurt beakers will do, check for the label 'PS';). The polystyrene will act as a binder, and a binder that is insoluble (unlike dextrin etc). This will burn when it rains on it etc but I am sure it would not any more once you submerge it into water - simply because the water would drain the heat too fast etc. The only way I can see this to work is in some kind of tube, where the emitted gases flow out so fast that they prevent the water from flowing in - so here you got a candle that works under water. Being a tube, it's going to be a torch, instead :)

Magnesium, once lit, supposedly burns in water, simply by reacting with it. I imagine it needs a special device, however, as an Mg ribbon, or even a solid 1x1cm rod of Mg is snuffed out by water. I tried both ...so I am not guessing!

BromicAcid - 19-1-2004 at 09:07

I believe manganese dioxide is fairly insoluble in water. It's not a powerful oxidizing agent but it is good to have a knowledge of other things that could be used.

I am a fish - 19-1-2004 at 09:37

Quote:

Magnesium, once lit, supposedly burns in water, simply by reacting with it. I imagine it needs a special device, however, as an Mg ribbon, or even a solid 1x1cm rod of Mg is snuffed out by water. I tried both ...so I am not guessing!


I've tried burning magnesium ribbon under water as well. It went out immediately.

BromicAcid - 19-1-2004 at 09:44

Most instances I've read about magnesium burning underwater regard the flares made from it. I have however seen magnesium powder explode from having water poured on it, of course resulting not only from the possibility of the steam explosion but of the reduction of the water and the formation of the highly explosive mixture of hydrogen and oxygen above it.

I do believe that magnesium can burn underwater on its own but I bet that it would have to be incredibly thin, even more so then the ribbon most of us have, or maybe we're going in the wrong direction, maybe it has to be thicker.... I seen it burn in CO2 once, it was very interesting.

In Principles of Pyrotechnics a formula that burns under water is listed, its composition is:
Mg 16%
Al 13%
BaSO4 40%
Ba(NO3)2 32%
8 parts flaxseed oil and 1 part MnO2 are added as binders



Edited to include more information relevent to the topic.

[Edited on 1/19/2004 by BromicAcid]

froot - 19-1-2004 at 10:01

Thanks for the help guys. Maybe if you added Al or Mg dust to your mixture, Chemoleo, it would help it along in a temperature draining environment but I'm sure temp of water is directly proportional to rate of burn/reliability. I suppose it can only burn in a gaseous environment so the mixture would have to expel lots of gas to work submerged and have a really low ignition temp-almost unstable.
KCLO3/4 seems to be the closest to ideal.
What if one had a center core down the length of Zn/ammonium chloride mixture that will react with any water it comes in contact with and keeps the burn marching on?:)

Iv4 - 20-1-2004 at 02:42

Nice idea but with that it would all go of effectivly at once :(.

THough come to think of it you could have a sealed pipe with sodium peroxide or something in it to give of oxygen.

AngelEyes - 20-1-2004 at 04:58

I managed to make some fuses that burn underwater. I used 'lifeboat matches' - they're fat matches with a long coating of combusible material. These could be lit and held underwater before being withdrawn yet still alight. This was a while ago, though, and the lifeboat matches I have recently acquired do not seem to be reliable for this purpose. The tube option seems best - maybe using NC lacquer or something to waterproof...not sure.
Underwater explosions are unbelievably fun though, and I don't know why...

Simple but should prob. work!

TPL - 23-1-2004 at 07:05

If you are just looking for a fuse that would burn under water, try the so called matchhead fuse...