Sciencemadness Discussion Board

Smoke without fire ?

itchyfruit - 14-7-2009 at 15:58

I'm looking into ways of producing smoke from a small hand held pot, something similar to dry ice (but not actual dry ice) and preferably without using heat or anything to dangerous(i'm not allowed to use pyro) any suggestions ?

If i can't make this happen i may resort to using the liquid you use in smoke machines,does anyone know what this is ?

Sedit - 14-7-2009 at 16:06

Smoke machines use vaporized mineral oil IIRC. At the very lest that could help you find the information your looking for.

kclo4 - 14-7-2009 at 16:06

Simply setting something soaked in hydrochloric acid, by something soaked in Ammonia solution will produce a white smoke of ammonium chloride in the air. Other acids that vaporize easily, such as that found in vinegar work. Ammonia cleaning solution on a rag by a rag of soaked in vinegar will show you how well this works. The more concentrated both are, the better.

Alternatively you could heat ammonium chloride as it will sublimate and produce a lot of smoke.

Edit: A video of it... http://www.youtube.com/watch?v=0xAoQp7i2YU&feature=relat...

Another good video: http://www.youtube.com/watch?v=EKUEOPU5Eyc&NR=1

If you were to have a fish pump bubbler in the ammonia, and have the gas then bubble through a solution of HCl,or vice versa, you'd have tons of smoke I bet. It is all about getting the gases to come out of solution and react, so if you increase the surface area, and agitate the solutions (bubbling) it should help a lot.

[Edited on 15-7-2009 by kclo4]

[Edited on 15-7-2009 by kclo4]

Formatik - 14-7-2009 at 16:30

The suggested ammonia and HCl is probably simplest and these two yield a thick, white, harmless NH4Cl fog. Many chemical methods of smoke generation have used hazardous compounds e.g. SO3 in chlorosulfonic acid, SiCl4, TiCl4, white phosphorus, etc.

merrlin - 14-7-2009 at 21:29

Quote: Originally posted by kclo4  

Alternatively you could heat ammonium chloride as it will sublimate and produce a lot of smoke.




I would advise against heating ammonium chloride to produce smoke. It decomposes below 280 Celsius to produce ammonia and HCl. In fact, it is an excellent reducing agent for doing die attach with gold/tin solder.

kclo4 - 14-7-2009 at 21:33

It recombines into ammonium chloride though, once it is below that temperature. I can't imagine it would be very dangerous at all, and no were near as dangerous as HCl, or NH3 alone.

UnintentionalChaos - 14-7-2009 at 21:36

If you turn up the heat on boric acid, which is similarly nontoxic, a lot of it evaporates, generating a very persistent, but light fog.

kclo4 - 14-7-2009 at 21:42

Are you sure about that? Boric acid dehydrates into boron oxide, letting off water.
The boron oxide might vaporize, but I think it would take a ton of heat to do it at any significant amount.

JohnWW - 14-7-2009 at 21:43

"Smoke" grenades, used by armies to make smokescreens to obscure advancing infantry soldiers from enemy gunfire, usually contain TiCl4, which on dispersal in and exposure to moist air produces clouds of very opaque hydrous TiO2. Possible alternatives are SiCl4 and SnCl4, although the latter has a substantially higher molecular weight. There was a thread here on smoke-producing substances like these a few years ago; I think www.roguesci.org also had such a thread, but it would be available now only in the recent backups that members have downloaded, and of which I have a copy.

UnintentionalChaos - 14-7-2009 at 21:47

Quote: Originally posted by kclo4  
Are you sure about that? Boric acid dehydrates into boron oxide, letting off water.
The boron oxide might vaporize, but I think it would take a ton of heat to do it at any significant amount.


Well, yes, it will lose water first first. You'll be surprized how much fume comes off the material even without intense heating. Rather high vapor pressure, I suspect.

merrlin - 14-7-2009 at 22:07

Quote: Originally posted by kclo4  
It recombines into ammonium chloride though, once it is below that temperature. I can't imagine it would be very dangerous at all, and no were near as dangerous as HCl, or NH3 alone.



If you decompose ammonium chloride by heating in air, the air molecules will inhibit recombination. The greater the dilution, the longer it will take to recombine. Dilution also reduces the size of the particles, so that you can have an invisible aerosol. This is a good way to irritate your respiratory tract.

merrlin - 14-7-2009 at 22:25

Quote: Originally posted by kclo4  
Are you sure about that? Boric acid dehydrates into boron oxide, letting off water.
The boron oxide might vaporize, but I think it would take a ton of heat to do it at any significant amount.


You are correct that the B2O3 vaporization will be insignificant, but I would not rule out "smoke" from some of the intermediate phases that might be produced during decomposition. See attached phase diagrams. I have never observed much "smoke" when fully dehydrating boric acid, but then I have heated it slowly to prevent foaming.

Attachment: B2O3-H2O_phase_diagrams.pdf (43kB)
This file has been downloaded 471 times

woelen - 15-7-2009 at 12:58

Personally I think that the heating of NH4Cl is one of the best options, and the second best in my opinion is HCl + NH3 from concentrated solutions. NH4Cl does decompose, but the recombination is very efficient and actually one almost can speak of sublimation of NH4Cl, although it really is a chemical reaction.

Stuff like TiCl4, SnCl4 or SiCl4 is not something I would advice. These produce the oxide TiO2, SnO2 or SiO2, but also very corrosive HCl. The white fume, produced by these liquid is extremely choking and very corrosive, to human organs, but also to metal tools.

itchyfruit - 15-7-2009 at 13:47

Thanks guys (and if any girls)
I showed sandy(the witch) the hcl/nh3 reaction today and she's happy with it. However she did inform me that she would like it to come from the hem of her cloak as well as the little pot in her hands, i have devised a method of doing this with the aid of a couple of syringes taped together and attached to a couple of plastic tubes connected to a open container with some cotton wool in it (to avoid spills).Although i think this will work i am still open to other suggestions as i'm a little concerned about her having conc hcl and nh3 in her pocket!!
The nh4cl method could be difficult due to the heat required.
I tried heating boric acid but didn't really get a massive amount of smoke and again this does involve an external heat source!!
Thanks again for your help :)

Formatik - 15-7-2009 at 14:18

From little pots you could put a layer of ammonia in the pots, and then lower a dish of hydrochloric acid. Be careful of spills, keep in mind though NH4Cl is pretty much harmless, NH3 and HCl are not. I would have an excess of NH3 over HCl in case, since it's less corrosive. I wouldn't put either of these substances in a pocket or cloak.

itchyfruit - 15-7-2009 at 15:16

I need to do it with out people being able to see what is forming the smoke.
Is dry ice something i'd be able to make? i'm sure it's not but it may be worth a try!

Formatik - 15-7-2009 at 16:27

In that case, I can only suggest to procure some dry ice.

itchyfruit - 15-7-2009 at 16:37

In that case, I can only suggest to procure some dry ice.

Any tips on how to do this ?

Formatik - 15-7-2009 at 16:47

Dry ice is available in some grocery stores, ice cream shops, welding supply stores, dry ice supply companies. You will have to look around near you.

itchyfruit - 15-7-2009 at 16:58

Theirs a welding shop not far away,is it just compressed co2 i need?

Formatik - 15-7-2009 at 17:10

Dry ice is compressed CO2. Some of those supply stores sell the solid CO2 (pieces or chunks). That's what you want. You don't need a CO2 cylinder.

itchyfruit - 15-7-2009 at 17:27

Cheers :)

woelen - 16-7-2009 at 13:00

Dry ice does not really give smoke, NH4Cl from NH3 and HCl is more impressive. Another risk of dry ice is the intense cold. Direct contact with the skin should be avoided at any cost. Contact with this material for more than a few seconds causes severe frostbite, which can be as harmful as strong burns!

itchyfruit - 16-7-2009 at 13:43

I spoke to a dry ice supplier today and they said the same thing,so nh4cl seems to be the way forward.
I was thinking of diluting the hcl and nh3 and (now this is just a thought) providing some sort of heat in the reaction vessel via a hand warmer or sodium acetate perhaps,what do you reckon?

kclo4 - 16-7-2009 at 15:01

How about 2 sponges inside a pipe with a fan blowing in it?
I bet that would work pretty well, especially if you used decently concentrated solutions of both.

itchyfruit - 16-7-2009 at 16:26

Could be a bit bulky for the hem of a cloak,plus i'd like to avoid using concentrated nh4/hcl for safety reasons,but maybe worth looking into if i can find a small enough fan.

MagicJigPipe - 23-7-2009 at 13:34

Look at how "professional" smoke machines work and make a miniature version that runs on a small 12V battery or something like that? Are you good with electronics?

Just because something gets hot does not mean it can't be close to someone's body. I think it can be done with a little work and ingenuity.

itchyfruit - 25-7-2009 at 06:05

The smoke machine i had (my brother broke it) worked by dripping an oily substance on a very hot metal plate, i think it may need a fairly large battery to produce enough power to do this.
I am at the moment looking into using smoke pellets (i should have thought of this before we use them for checking flues).

watson.fawkes - 25-7-2009 at 10:18

Quote: Originally posted by MagicJigPipe  
Look at how "professional" smoke machines work and make a miniature version that runs on a small 12V battery or something like that?
It's vaporization onto a hot plate. Electrical power from batteries is horribly inefficient for this. I'd look at repurposing a butane-powered soldering iron as the heating element. If it needs to be small, you'll need one with an adjustment valve to get the heat production down into the right range.

itchyfruit - 25-7-2009 at 10:32

Butane powered hot tongs maybe ?

Mr. Wizard - 25-7-2009 at 20:49

I would just like to state that breathing ANY kind of smoke is bad thing for your health and lungs. I would suspect distilled water or some normal saline would be harmless, maybe even dry ice with distilled water, but breathing atomized mineral oil, or other liquids is not a good thing. Once something is in your lungs and touches a surface it can only come out through your blood stream, or stay there. Other solids, even though they may not harm you immediately are often time bombs. I'll mention silica dust and asbestos as two famous 'inert non toxic' examples. Any smoke or dust generated by a pyrotechnic device should be avoided as well. Would you inject the residue from a pyrotechnic device into your bloodstream? Inhaling a substance will expose your blood to it in seconds.



[Edited on 26-7-2009 by Mr. Wizard]