Sciencemadness Discussion Board - Perchloric acid and bismuth

Perchloric acid and bismuth

woelen - 4-8-2010 at 11:47

This is a really remarkable find I want to share with others. I found this in an old document about perchloric acid. Normally, aqueous (60%) perchloric acid does not react with metals, or just as a strong acid with evolution of hydrogen gas. Using this knowledge, I already made chromium(III) perchlorate from chromium metal and perchloric acid, I also made cobaltous perchlorate, magnesium perchlorate (fairly violent reaction, production of hydrogen gas, but not much different from reaction with hydrochloric acid). I also have done experiments with boiling 60% perchloric acid and KI and even that does not lead to a redox reaction with the perchlorate ion.

But with bismuth things are totally different. I was warned about the risks of this reaction, so I only took very small amounts. 1 big drop of 60% perchloric acid was mixed with a small spatula of bismuth powder (200 mesh, 99.92% purity according to documentation with the powder). The chemicals were mixed such that a grey slurry was obtained. No gas was produced, no visible reaction. I then put this in a heating spoon and put it above a flame. Soon, the liquid starts bubbling somewhat (boiling away of water) and then suddenly there is a really impressive BOOM

. It made me really be scared stiff! This reaction is much more impressive than I had imagined.

I have done many tests afterwards with even smaller quantities. Even a tiny speck of just 1 mm³ already gives a loud PANG sound.

[Edited on 4-8-10 by woelen]

densest - 4-8-2010 at 12:05

Bi2O3, Mg-Al, and CuO are the ingredients for the crackling microstars currently popular in fireworks shells. The mixture 75/15/10 is formed into tiny cubes and bound (20%) into larger stars with an approximate gunpowder/aluminum mixture (80%). As the larger stars burn, they release & ignite the microstars, which explode.

I have no idea if these stars are reacting in any similar way, but it was surprising to me to learn that the bismuth trioxide was replacing lead dioxide, a surprisingly potent oxidizer...

Jor - 4-8-2010 at 15:02

I would imagine the bismuth being oxidised, and when the water has boiled away, bismuth perchlorate being formed, wich I think explosively decomposes to bismuth chloride and oxygen, just like I remember some other metal perchlorates do (I think some heavy metal perchlorates). However, I;m not sure.

I hope you evaporate the perchloric acid outside, because these vapours will reacts with wood and and cellulose based material, to make them very flammable/explosive.

JACS 1935

The WiZard is In - 4-8-2010 at 15:33

Quote: Originally posted by woelen

This is a really remarkable find I want to share with others. I found this in an old document about perchloric acid. Normally, aqueous (60%) perchloric acid does not react with metals, or just as a strong acid with evolution of hydrogen gas.

[snip]

Bismuth-Perhcloric-acid-1-800.jpg - 619kB

Bismuth-Perhcloric-acid-2-800.jpg - 636kB

woelen - 4-8-2010 at 22:52

This is an interesting read. I did not know this document. It indeed is very peculiar that this strange phenomenon only occurs with bismuth and not with other metals. I also learned something from this. Even things which seem safe to do can hold a nasty surprise. One must not think of what could have happened if I decided to make a few grams of bismuth perchlorate by dissolving some bismuth metal powder in a few ml of perchloric acid

. I have done that with chromium and cobalt and luckily I first came to know of the bismuth thing before I ever attempted to make bismuth perchlorate.

@Jor: Don't worry about explosive fumes. The amounts I have evaporated are so tiny (all together certainly less than 0.05 ml) such that this cannot pose any threat to my lab surroundings. I know of the risks and I never evaporate larger quantities of perchloric acid such that fumes are formed. Besides that, of that 0.05 ml also most is decomposed in the explosion reaction.

[Edited on 5-8-10 by woelen]

Zinc - 5-8-2010 at 07:03

Here is a thread that mentiones the bismuth explosive http://www.sciencemadness.org/talk/viewthread.php?tid=5112

Rosco Bodine - 5-8-2010 at 11:30

There is reportedly a catalytic activity for Bi2O3 as a component of anode coatings useful for the electrolytic formation of perchlorates. It would seem entirely possible that there may be a relationship between the mysterious unstable reaction product of Bi and perchloric acid and the reported electrocatalytic effect of Bi on perchlorate formation. Now there's something to think about, huh.

AndersHoveland - 28-7-2013 at 04:57

For best results in forming the explosive brown layer, it is recommended to heat 60% HClO4 to 110 °C before adding the bismuth.

One possible explanation I can think of is that the bismuth might be in the +1 or +2 state, and is protected from further oxidation by the simultaneous precipitation of insoluble BiCl3 which surrounds it. Just a guess.

I am not sure what is happening here, but the following reaction that I found might possibly be able to shed some light:

Quote:

"15% nitric acid solution in ethanol was used to clean a bismuth crystal. The solution decomposed violently after this treatment and projected the content of the container in the extraction hood in which it was placed. Mixtures with less than 10% of nitric acid in alcohol are the only ones to remain stable for short periods of time. They should never be stored."

Chemical Risk Analysis: A Practical Handbook, Bernard Martel

The author suggested that some fulminate of bismuth might be forming. It does seem most odd.

[Edited on 28-7-2013 by AndersHoveland]

Fantasma4500 - 28-7-2013 at 06:37

i believe Axt has a video of Pb(ClO2)2 decomposing rather fast or well deflagrating it is more..
i have always been curious about lead chlorate or lead perchlorate

perhaps bismuth perchlorate could be made by NH4ClO4 + (BiO)2CO3 > Bi(ClO4)3? + (NH4)2CO3

problem would be that this reaction would be easiest to make with water, as in mixing both reagents (aq)
it could perhaps be done both in anhydrous state? they mention in the picture of the old book that it doesnt work when it gets anywhere near water
perhaps even bismuth chlorite could be experimented with in a more safe manner, to see if it has similar properties to lead chlorite, then use lead for the perchlorate, if the bismuth seems less violent as chlorite?

12AX7 - 28-7-2013 at 07:39

It's not Bi(ClO4)3. The article mentions that it is easily prepared.

Don't suppose this reaction could be carried out under the watchful eye of some atomic spectrometer, given suitable safeguards?

Tim

Tdep - 15-7-2015 at 19:09

I did this experiment the other day and quite enjoyed the resulting explosions. Here's my video I made from the reaction: https://youtu.be/mQaGuYsqQ98

So, still no thoughts on the makeup of the coating? I tweeted Nurdrage and he suggested 'The instability is not unique to bismuth and can occur with many different metals' however to see it DDT in such small amounts without a fuel, makes me sure there's something more interesting going on than just bismuth(II) perchlorate (which we know it isn't)

nitro-genes - 16-7-2015 at 08:10

Interesting, maybe bismuth is unique in being able to reduce perchloric acid to lower oxychlorites such as (hypo)chlorites of bismuth with unknown valence. Chlorites of some heavy metal salts are very exposive. This could also concur with the elemental analysis in the paper posted earlier in this thread, although the interpretation was false.

https://en.wikipedia.org/wiki/Chlorite

[Edited on 16-7-2015 by nitro-genes]

PHILOU Zrealone - 16-7-2015 at 12:26

Maybe it is like other very reactive reductive metals. There is formation of specific valence as surfacial crust and upon reaction with the naked metal, there is a violent oxydoredox.

The case of KO2 on potassium is a typical example...cutting the crust provoques an explosion because of the underlying native K.

Oscilllator - 16-7-2015 at 20:04

Quote: Originally posted by PHILOU Zrealone

Maybe it is like other very reactive reductive metals. There is formation of specific valence as surfacial crust and upon reaction with the naked metal, there is a violent oxydoredox.

The case of KO2 on potassium is a typical example...cutting the crust provoques an explosion because of the underlying native K.

Wait. If the potassium is already in contact with the KO2 (as a coating), then how would cutting the crust change anything?

nitro-genes - 17-7-2015 at 02:20

The superoxide crust forms very slowly under mineral oil, in which case only very small amounts of oxygen get to the potassium metal per unit of time. Since it is so slow, there is not enough to provide the activation energy for the reaction to commence. When cut, maybe a relatively large surface is instantly exposed to oxygen, providing the activation energy. It maybe acting like a sort of "fuse".

Similar may be ballmilling fine aluminium powder, when the drum is allowed to very slowly leak in oxygen over days, nothing happens. When you open the drum at once, it heats up pretty fast and eventually bursts into flames.

[Edited on 17-7-2015 by nitro-genes]

Tdep - 20-7-2015 at 06:24

Quote: Originally posted by nitro-genes

Interesting, maybe bismuth is unique in being able to reduce perchloric acid to lower oxychlorites such as (hypo)chlorites of bismuth with unknown valence. Chlorites of some heavy metal salts are very exposive. This could also concur with the elemental analysis in the paper posted earlier in this thread, although the interpretation was false.

https://en.wikipedia.org/wiki/Chlorite

[Edited on 16-7-2015 by nitro-genes]

I like this theory, perhaps the solid could be prepared using chlorine dioxide or maybe chloric acid, generated by sulfuric acid and potassium chlorate. The risk of detonation is very high but if any black surface crust is seen, it gives good evidence that the bismuth is reducing the perchloric acid and then reacting

nitro-genes - 22-7-2015 at 18:33

Chlorate and acid to generare chloric acid is a good idea.

Its extremely unstable at higher concentrations and ignites anything organic, though a small scale simple test would be to dissolve a small amount of bismuth chloride in icecold dilute HCl and add a spatule of potassium or sodium chlorate. A black explosive precipitate would indicate bismuth chlorite, although it is possible that upon reaction of perchloric acid with the metal more happens, perhaps oxidation of bismuth tot higher valence cation, or complex formation.

[Edited on 23-7-2015 by nitro-genes]

Tdep - 22-7-2015 at 18:58

All reports suggest it is not stable towards water, needed concentrated perchloric acid to form, so the dilute HCl idea doesn't seem probable to me. Could sodium chlorite be added to a cold solution of perchloric acid and bismuth, showing it forming without heating? I don't have chlorites, but I do have chlorates, might try the acid/chlorate method later today

nitro-genes - 23-7-2015 at 01:33

It may be that only a certain strenght of perchloric acid is needed to act as an oxidizer instead of an acid. Is the black crust once formed also dissolved/destroyed in water? If so dilute HCl may not be applicable, good point.

HCl also produces hypochlorite and chlorine gas upon reacting with chlorates, so sulfuric acid may be a better option indeed, provided bismuth sulfate is water soluble.

https://en.wikipedia.org/wiki/Chlorine_dioxide

Sodium chlorite is reasonably stable, if you were able to produce a small amount of it, metathesis from more concentrated solutions could be tried to produce the bismuth chlorite. Be very carefull when making gasseous chlorine dioxide, the gas at more than a few percent in air is explosve itself.

[Edited on 23-7-2015 by nitro-genes]

PHILOU Zrealone - 24-7-2015 at 08:20

Quote: Originally posted by nitro-genes

Chlorate and acid to generare chloric acid is a good idea.

Chloric acid is stable up to 30-40% above it decomposes into ClO2 and other chloride oxydes.

Chloric acid is unstable in contact with chloride or HCl...it is destroyed into Cl2(g)...

Chloric acid is best done by reaction of H2SO4 (diluted <40%) and chlorate.

This process can be used to make chloric acid and upon slow heating and evaporation disproportionate into HClO4...
In the disproportionation process some HCl is formed and account for the "low" 50% yield...
4 HClO3 --> 3 HClO4 + HCl
HClO3 + 5 HCl --> 3 Cl2 + 3 H2O

[Edited on 24-7-2015 by PHILOU Zrealone]

blargish - 24-7-2015 at 14:10

I also have taken a recent interest in this phenomenon and have conducted a few basic trials by dropping some conc. perchloric acid onto a piece of bismuth on a ceramic dish and heating.

The black/brown crust was incredibly sensitive and detonated when touched with a metal spatula. It was destroyed by water, and also dissipated upon standing in air for a prolonged time. I've attached a couple clips I shot: the first clearly shows the formation of the black crust during the heating step, and the second is a slow-mo shot of a detonation.

Attachment: Bismuth Crust.mp4 (9.5MB)
This file has been downloaded 869 times

Attachment: Detonation.mp4 (2.2MB)
This file has been downloaded 818 times

I think it's important to note that the original paper states that the product of hydrolysis of the mystery explosive compound was an acidic solution of Bi3+, Cl-, and ClO₄- which does seem to me as a potential indicator towards it being some sort of lower oxychlorite undergoing disproportionation in water. It actually bears similarity to PHILOU's equation for the disproportionation of chloric acid...

[Edited on 24-7-2015 by blargish]