Official pyrotechnics thread!

[woelen]

woelen: You can get chemicals easily there but you can't do any pyro? That sucks so bad!

Nice set of descriptions there too! I've never actually worked with or even seen any azides but I'm heared they can be quite dangerous at times.

And I'm shure everyone will be interested to hear the results of your experiment!

 

When I started home chemistry a few weeks ago I decided to talk to the local police about whats permitted and whats not - they were happy that I did actually. They basically said anything that does not hurt or disturb people after a certain time - anything below the level that could hurn someone is acceptible without a lisance. Fortunatly I do not intend to mess with this stuff without training first (Some kid arround here did try and mamaged to hurt himself quite badly because he did not know what he was doing)!

 

I have a question for who ever can answer it: why is Sulphur used in a mix? I'm not shure it actually provides any colour so does it do something for the actual reaction like regulate speed or something?

 

Cheers' date='

 

Ryan Jones[/quote']

Yes, as far as legal issues are concerned, the Netherlands is a nice country for home chemists, as long as you don't do any pyro.

 

I've imported quite some chemicals from abroad and that is no problem at all, also oxidizers like KBrO3 can be had without problem. Possession of red P is no problem here, as opposed to the USA, where with war on drugs a lot of paranoia exists at the moment and where a lot of chemicals are on so-called "list X", "list Y" etc. Fortunately we hardly have that kind of hassle over here. BUT, as soon as pyro is involved it turns 180 degrees. I'm even afraid of burning 1 gram of BP in the open. The smoke of that has such a typical "fireworks smell" and that already can give you quite some troubles. If someone smells it and calls the police, then chances are that all chemicals are confiscated. So, I am careful with what I do, and then I can be open with it. I have nothing to hide.

 

So, with the azides I only make mg quantities of these explosives and if I detonate them I do that with no more than 50 mg. In that way no neighbours will be alarmed and I cannot cause any harm with such small amounts.

It also has a big advantage: Using such small quantities allows me to do a LOT of experiments, even with small stock amounts of chemicals .

[RyanJ]

Well, looks like to get some freedom you need to get rid of some, in this case you cna get chemicals but you can't do some interesting experiments with them.

 

Its the opposite here, you can't get a load of the stuff from arround here but when you can say import it you'r allowed to do pyro as long as you don't endanger anyone can.

 

Like I said its normally some idiot that gets all the people a bad name, I know no chemists that live close too me but I know of one kid who got hurt real bad because he messed with acetone peroxide and it wxploded with him in contact with the stuff - not nice but it was his own fault.

 

Anyway back to the topic.

 

My next quesiton to the experts or anyone else: Why do things explode? What is it about them that makes then react so fast?

 

Before we go into this topic let me say that there are two types of explosives (Mainly anyway) HE's and LE's in this care I'm talking about HE's such as nitroglycerine and RDX

 

Cheers,

 

Ryan Jones

[jdurg]

Things explode because the bonds holding the molecule(s) together are very weak in comparison to the bonds that are formed in the products they make. Remember, when bonds form they release energy, and when bonds break it requires energy. If you form a lot of strong bonds in a chemical reaction, it will release a lot of energy. If little energy is required to break the initial bonds, then all the energy generated can be absorbed by the products.

 

When a compound explodes, the initial solid or liquid tends to form many moles of gas (More moles of gas than initial moles of explosive). These gases are typically water vapor, nitrogen gas, and carbon dioxide. Nitrogen gas has a VERY strong triple bond in there, and CO2 has two fairly strong double bonds. So a great deal of energy is released when the products form. This energy gets absorbed by the gases which increases their temperature. At a higher temperature, the gas expands and exerts a greater force. In a true explosive, the gases expand faster than the speed of sound and create a shock wave which results in the 'KABOOM'.

 

Some compounds won't explode if out in the open because they don't generate gaseous products fast enough to make a 'BOOM'. Black powder and nitrocellulouse are examples of these products. If you confine them, however, then they can explode because the expanding gases have no place to go and the resulting build up of gas pressure causes their confinement to break and the gases rush out going 'KABOOM'. But this isn't a true chemical explosion as it is more of a physical explosion.

 

As an example of an explosive, let's take a look at nitroglycerin. Glycerol trinitrate is a great example of an explosive. (H2C(ONO2)-CH(ONO2)-CH2(ONO2)). All of the bonds in the compound aren't exactly super strong bonds. They are all single bonds of either the N-O, C-O, or C-H variety. The nitrate groups are also very bulky so there's a lot of steric strain placed on the molecule. It doesn't take a lot of energy to snap one of the bonds and start forming one of the three products; N2, CO2, or H2O. The energy released when the products form is so high that it catalyzes the breaking of another molecule of nitroglycerine and suddenly there's a loud KABOOM!

 

So an explosive is simply a chemical with a lot of strain and weak bonds which decomposes into numerous gaseous products with a lot of strong bonds.

 

With the earlier discussion of azides, I want to also let people know that azides are up there with cyanides in terms of toxicity. I would consider azides a bit more dangerous because not only are they as toxic as cyanides, but azides can explode while cyanides can't. When an azide is dissolved in water, it forms small quantities of HN3 (azotic acid) which is INCREDIBLY toxic. So while woelen does know what he is doing with the stuff, an inexperienced chemist could really hurt themselves by having some azide go off in their face, or by inhaling the HN3 fumes.

[H2SO4]

oh my god a pyrotechnics thread. MY WISH HAS COME TRUE!!!

 

 

 

 

Not being cocky or anything (well i guess i am) but i have some expierence in the pyrotechnics field. Im just starting it up= again becuase its winter annd in the summer i have a fear of burning down california. But ya, so besides chemcals we should share techniques for making bp, stars, tubes, plugs, ect..

 

 

just curiosu are we allowed to speak of exploding foreworks (i can understand if flash powder explosives are forbidden, but black powder is another story).?

[Phi for All]

just curiosu are we allowed to speak of exploding foreworks (i can understand if flash powder explosives are forbidden, but black powder is another story).?

You can speak of them but no formulae, please. Those of you who know how to do it will understand. Those who don't will be in the dark, but they will still have their fingers.

[RyanJ]

You can speak of them but no formulae, please. Those of you who know how to do it will understand. Those who don't will be in the dark, but they will still have their fingers.

 

Yea thats the way it should be I am afraid thanks to people who would go out and try and make the stuff! No positing how you make the matrerials or the devices because we want everyone reading this thread to keep their finders, halds and even lives Posting how the materials and stuff work should be fine as long as no-one can make that into a bomb and or firework

Accodring to the rules (Which the mods also said were fine), you can talk about the making as long as it does not allow someone else to make the device / material from what you have said (Just miss somehting out or whatever) Flash powder again is fine just gon't tell epople how to mkar this stuff... YT has already talked about it in this thread somewhere!

 

jdurg: Great description! And I right in saying that things that explode just burn really fast or is there nore too it than that?

 

Cheers,

 

Ryan Jones

[woelen]

Yea thats the way it should be I am afraid thanks to people who would go out and try and make the stuff! No positing how you make the matrerials or the devices because we want everyone reading this thread to keep their finders' date=' halds and even lives Posting how the materials and stuff work should be fine as long as no-one can make that into a bomb and or firework

Accodring to the rules (Which the mods also said were fine), you can talk about the making as long as it does not allow someone else to make the device / material from what you have said (Just miss somehting out or whatever) Flash powder again is fine just gon't tell epople how to mkar this stuff... YT has already talked about it in this thread somewhere!

 

jdurg: Great description! And I right in saying that things that explode just burn really fast or is there nore too it than that?

 

Cheers,

 

Ryan Jones[/quote']

No, explosives do not simply burn very fast. As Jdurg already pointed out, explosive compounds have a few properties:

1) Their bonds are quite weak and contain a lot of potential energy

2) The decomposition products are gaseous at the temperature at which the reaction occurs

3) There is a mechanistic pathway, which makes breakdown of the explosive molecules easy

 

Many explosives (but not all) in the same molecule (or salt) have both an oxidizer and a reductor. Some examples:

 

 

--------------------

Nitroglycerine (much better name is glycerol trinitrate, because it is a triple nitrate ester). The CH2.CH.CH2 skeleton is the reductor, the three .ONO2 groups are the oxidizer.

 

--------------------

TACN (tetrammine copper (II) nitrate, a salt, having formula [Cu(NH3)4](NO3)2, which contains the deep blue tetrammine copper (II) ion. Here the NH3 is the reductor and the NO3(-) is the oxidizer: It decomposes thus:

 

Cu(NH3)4(NO3)2 ---> Cu + 2N2 + 6H2O

 

Here follows a picture of this stuff. Yeah, I made some of this . It is sufficiently stable to keep it in a display vial and showing it to people .

 

-----------------------

PETN (pentaerythritol tetranitrate), C(CH2ONO2)4. Easy to prepare if you have pentaerythritol C(CH2OH)4, a four-fold primary alcohol. I'm afraid for US-citizens this is a list XXX compound, because it can be used to make drugs, over here it is not that hard to get your hands on. PETN is a very powerful explosive. It has a VOD of 8400 m/s (this means that if you have a large mount of PETN and it is detonated, that the wave front at which the decomposition reaction occurs moves through the solid at a speed of 8400 meters per second!). Again the C(CH2.)4 skeleton is the reductor and the .ONO2 groups are the oxidizer.

 

As you see, many explosives contain nitrate and now you probably also understand why in many countries nitric acid is a regulated chem.

 

 

Other powerful and sufficiently stable explosives of the reductor/oxidizer type are perchlorate esters and perchlorate salts, where the cation contains hydrazine, ammonia or organic ligands, such as (en). Organic peroxides also frequently are highly explosive, containing the organic skeleton as reductor and peroxo-groups as oxidizer. These peroxide explosives are really crap and please do not experiment with that stuff. Too many people have lost limbs or more by fiddling around with that.

 

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As I said, not all explosives have an internal oxidizer/reductor pair in their molecule. Examples of these are the azide-explosives, but also crap like NI3 (or better: NI3.nNH3). These explosives simply are explosive, because of very weak bonds or highly strained bonds in their molecules. An azide like Pb(N3)2 simply decomposes, giving Pb and N2 gas. This decomposition goes with extreme violence.

 

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Finally, and that is most remarkable, there also are explosives, which do not give gaseous products on decomposition. Yet, they are quite powerful. An example of such an explosive is silver acetylide, Ag2C2, and the related copper (I) acetylide, Cu2C2. These contain the C2(2-) ion. They are very easily prepared by the home chemist, but they also are quite powerful and impact sensitive. Ag2C2 has a VOD of appr. 3.5 km/s. These explosives are very dangerous due to their secondary effect. On detonation, a very hot and very finely divided cloud of elemental carbon is produced, which in air burns with an intense hot and bright yellow/orange flame. No childrens toys . I once made a small amount of this, but I dare not keep it around. I destroyed it immediately, enjoying the nice flash.

[RyanJ]

Great description woelen! So burnins if nothing like explosions then? Makes sence now you put it that way

 

Not many people know this nut nitroglycerine is used to treat people after a heart attack although itss minute quanities mied with other things to stabalise it but its also given the name glycerol trinitrate so people don't realize they are basically eating an explosive! I told my grandfather this and he thought it was funny to know hw was eathing somehting so unstable!

 

Maths question for you guys now, how does one calculate the blast radius for an explosion? If there a formula to do this?

 

And another one too: How do those shaped blastin charges work like the ones they use to cut through steel lines in demolitions, why not just use a normal explosive charge?

 

And yea Azides sound nasty - do these things have any practial uses other then blowing small quantities of them up? Seeing how toxic they are I would not thing so.

 

Cheers,

 

Ryan Jones

[woelen]

And yea Azides sound nasty - do these things have any practial uses other then blowing small quantities of them up? Seeing how toxic they are I would not thing so.

In fact, azides are made in multi-tonne quantities every year. Most people have a few ounces of azides around their home and some even almost a pound . Probably you (I think in your case your parents) also have. Think good and you'll find the answer!

[RyanJ]

In fact, azides are made in multi-tonne quantities every year. Most people have a few ounces of azides around their home and some even almost a pound . Probably you (I think in your case your parents) also have. Think good and you'll find the answer!

 

Actually I'd rather not know where they are

 

Can you provide any helpful hints to where these may be? I really can't think of anywhere... maybe bleach because its meant to kill bacteria and the like.

 

Are the azides reactive at all by the way?

 

Back to fireworks for me with another question: is is possible to make a ballanced reaction for the reactions themselves? It seems that under such high temperatures and pressures then just about anything could form as the products....

 

Cheers,

 

Ryan Jones

[jdurg]

Nitroglycerine is VERY effective in treating angina because it is so unstable and decomposes so readily. It thusly gives off a great deal of NO once absorbed into the body, and NO is an incredibly potent vasodilator. By opening up the blood vessels it allows the heart to get more blood and also lowers blood pressure. This is the reason why you get such a horribly vicious headache if you work with nitroglycerine. The stuff you see used in hospitals to treat patients is VERY dilute, so if a molecule or two goes off it can't set off a chain reaction. Still, it's very potent at what it does. It's also another reason why it's so dangerous to work with. If you're in the process of making a substantial amount of the stuff and accidentally get the concentrated explosive on your hand, it can make you pass out and knock over your reaction vessel. You're funeral would then be very cheap as there wouldn't be much left of you to bury.

 

As for the azides, sodium azide is one of the most important chemicals out there in terms of safety. In modern automobiles with airbags, a few grams of sodium azide exist in the primer. In the case of an accident, a sensor detects that an accident has occured and sets off a small electrical charge on the pile of sodium azide. This instantly causes it to detonate which immediately fills the airbag with nitrogen gas. This controlled explosion can save your life.

[RyanJ]

As for the azides' date=' sodium azide is one of the most important chemicals out there in terms of safety. In modern automobiles with airbags, a few grams of sodium azide exist in the primer. In the case of an accident, a sensor detects that an accident has occured and sets off a small electrical charge on the pile of sodium azide. This instantly causes it to detonate which immediately fills the airbag with nitrogen gas. This controlled explosion can save your life.[/quote']

 

jdurg: I knew it was used but I never actually knew why it worked so thanks for that! Another case of explosives saving lives. What does glycerol trinitrate look like anyway?

 

Finally a case of an explosive saving someones life! I wonder how many lives this has actually safed and if it were not for the "maniac explosive chemists" all those people would have died!

Damn, I should have remembered that - I watches a show about car safety not a week ago - I'm an idiot!

 

How much of this stuff does it take rto fill an airbag them? I'm gusessing its not that much

 

Oh, yea another pyro related quesiton for a mod or anyone! Would a copper oxide and aluminium thermite work? I read that something like this was used in some pyro show a while ago, just wondering if it was true! Apparently this is more like flash powder than thermite

 

Cheers,

 

Ryan Jones

[woelen]

Azides have very practical applications. Each modern car contains a canister of sodium azide in an airbag. An acceleration sensor triggers a heater, when the acceleration (better: deceleration) goes above a certain limit. The heat of the heater (usually a simple wire inside the pellets of sodium azide) causes this to soft-explode and within 50 ms or so, the entire airbag is filled with non-toxic nitrogen gas. The NaN3 decomposes to Na-metal and N2 gas. Usually some other chemical is molded around the canister to neutralize the sodium metal formed just in order to avoid fire. Most cars have a few ounces of NaN3. (Ah, jdurg was first while I was typing, well done jdurg !)

 

Another application of azides is as primary detonator for situations, where the arms can become moist or wet. Lead azide remains explosive, also when it is wet. A small amount of lead azide is used as primary detonator to start the detonation of a larger less sensitive (but usually less toxic and more powerful) load.

 

------------------------------------------------------

 

The high temperatures in fireworks, explosives and so on, indeed make it difficult to describe the reactions with a nice stoichiometrically well-defined chemical equation. However, one usually can state that nitrogen in the compounds is released as N2, hydrogen almost invariably is released as H2O and carbon and sulphur mostly are released as CO2, SO2 or a carbonate salt and a sulfate salt. Of course, it also depends on whether sufficient oxidizer is present in a composition. E.g. if you have C, S and KNO3 as BP, when the mix is KNO3-deficient, then not all sulphur is oxidized and some sulfides are formed. If the KNO3 is present in excess amount, then part of it is not reduced further than KNO2 and in fact, this sometimes is used as a means to make nitrites from the esaier to obtain nitrates.

[jdurg]

Glycerol Trinitrate is a yellowish oily liquid. To me, the stuff looks a lot like vegetable oil, only not as intensely yellow.

 

In an unrelated note, I do know that Barium Oxide (BaO) and aluminum powder is used to create pure barium metal via a Barium Thermite.

[RyanJ]

Glycerol Trinitrate is a yellowish oily liquid. To me' date=' the stuff looks a lot like vegetable oil, only not as intensely yellow.

 

In an unrelated note, I do know that Barium Oxide (BaO) and aluminum powder is used to create pure barium metal via a Barium Thermite.[/quote']

 

Vegetable oil? Something so powerful looks so humble? How wierd!

 

 

So Barium will work - what others do you think would work. How about aluminium oxide and magnesium?

 

Cheers,

 

Ryan Jones

[RyanJ]

Another question:

 

If you added small quantities of say gold to a firework, what colour would that produce?

 

Cheers,

 

Ryan Jones

[woelen]

I expect not very much, maybe you get some sparkles of molten gold drops, but these would not be spectacular. Iron, aluminium or magnesium sparkles are more spectacular, because they do not only glow, but they also burn, which gives much added light.

 

If I ever win a kilo of gold powder or gold chloride on eBay for a few dollars, then I'll give it a try but chances are not good at all. I have some HAuCl4, but that stuff costs $30 per gram, so that's not something for a firework composition .

[RyanJ]

I expect not very much' date=' maybe you get some sparkles of molten gold drops, but these would not be spectacular. Iron, aluminium or magnesium sparkles are more spectacular, because they do not only glow, but they also burn, which gives much added light.

 

If I ever win a kilo of gold powder or gold chloride on eBay for a few dollars, then I'll give it a try but chances are not good at all. I have some HAuCl4, but that stuff costs $30 per gram, so that's not something for a firework composition .[/quote']

 

$30 for a gram?! Expensive, whats it used for?

Whats the name of that substance, Chlorine hydrogen alurate(III)?

 

Does anyone have a colour list for flame tests? I'm looking for one because I'm trying to work out how they get the colour combinatiosn in fireworks by mixing x with y

 

Cheers,

 

Ryan Jones

[woelen]

$30 for a gram?! Expensive, whats it used for?

I use it for toning photographic images. Gold-toned pictures are among the most beautiful pictures. Besides that, I also use it for experiments .

 

Whats the name of that substance, Chlorine hydrogen alurate(III)?

HAuCl4 is called tetrachloroauric acid. It is a fairly strong acid and there also are salts of this, the anion AuCl4(-) is called tetrachloroaurate (III). It is a deep yellow/orange anion and it is one of the most stable compounds of gold.

 

Does anyone have a colour list for flame tests? I'm looking for one because I'm trying to work out how they get the colour combinatiosn in fireworks by mixing x with y

Keep in mind, that flame tests do not necessarily yield the same color as when a metal is used in fireworks. The observed colors are affected by subtle interactions. E.g. copper salts frequently give green flame tests, but in pyrotechnic mixtures they may also be blue as I've understood. So, there is more to say about that.

[RyanJ]

I use it for toning photographic images. Gold-toned pictures are among the most beautiful pictures. Besides that' date=' I also use it for experiments .

 

 

HAuCl4 is called tetrachloroauric acid. It is a fairly strong acid and there also are salts of this, the anion AuCl4(-) is called tetrachloroaurate (III). It is a deep yellow/orange anion and it is one of the most stable compounds of gold.

 

 

Keep in mind, that flame tests do not necessarily yield the same color as when a metal is used in fireworks. The observed colors are affected by subtle interactions. E.g. copper salts frequently give green flame tests, but in pyrotechnic mixtures they may also be blue as I've understood. So, there is more to say about that.[/quote']

 

Thanks woelen!

 

As for the flame tests I'll keep what you said in mind

 

Cheers,

 

Ryan Jones

[jdurg]

Typically speaking, when a powdered metal is used in a firework it tends to just give off white sparks and not a whole lot of color as there really isn't a movement of electrons, just a transfer of energy. If you want color, you have to go and use a salt of a metal.

[RyanJ]

Typically speaking, when a powdered metal is used in a firework it tends to just give off white sparks and not a whole lot of color as there really isn't a movement of electrons, just a transfer of energy. If you want color, you have to go and use a salt of a metal.

 

I always thought the salt would vary the colour of the actual elements so salts are really used because pure metals produce only white colours? Sweet!

A question on that note then, do different salts of the same metal make different variations of the colours?

 

Cheers,

 

Ryan Jones

[YT2095]

yes different salts of a same metal will give differing results (always within the same color band range though), Barium Chloride will differ from the Carbonate or the Nitrate etc...

 

as for Metal Fuels, salts are added in small quantities as color Adjusters, again using Barium, it`s Chlorate is often used to counter the Mild lilac color of Potassium in salutes (flash powder) to make a PURE white flash.

 

care has to be taken also that saturation doesn`t occur, for that a color wheel can be used as a rough guide, at saturation, most all becomes white(ish) with only a Tint of the color and looks dreadfull, it`s also a waste of good chems! (and that`s a SIN!)

[RyanJ]

Sorry YT2095, did notsee your reply - I did not get a topic notification for some reason!

 

Another question, what is the use of Sulphur in black powder, are there ever cases where something other than sulphur (E.G. Phosphorus) is used?

 

Cheers,

 

Ryan Jones

[aj47]

I have a question regarding TNT. Ive always understood the reason it is so explosive is becasue the nitro and methly groups withdraw electron density from the bezenze creating weak bonds, correct?

If so wouldn't a benzene with further more elctronegative groups added on be more effective or is this too impractical. e.g. tri flouro benzene if such a chemical exists?