Sciencemadness Discussion Board

Wierd...

Zinc - 8-7-2006 at 12:32

Our chemistry teacher gave me and my friend some potassium chlorate (one of many chemicals she gave us) and we mixed it with magnesium powder. We tried to light it with a butane torch bud it didn't ignite:(. The potassium chlorate is 20-30 years old but the bottle was never opened before.
The same goes for KBrO3. I mixed it with sulfur (I know it is dangerous to do that) and tried to light it but it didn't ignite:(. The potassium bromate was also 20-30 years old and never opened before. I am sure that nothing was wrong with the magnesium and sulfur. Do you know why the mixtures didn't burn? I know that we mixed them good. The powders were as coarse as flour. Do the KCLO3 and KBrO3 have a limited shelf live?

Bert - 8-7-2006 at 12:39

If your Mg was as old as your oxidizers, it has probably completely oxidized in storage unless it was sealed in an inert atmosphere. Or your chemicals are perhaps mislabeled.

12AX7 - 8-7-2006 at 13:21

FYI, I've never had good luck igniting loose KClO3 and MgAl powder I made myself. Explodes just fine with charcoal and confinement, go figure.

Tim

Zinc - 8-7-2006 at 14:12

Quote:
Originally posted by Bert
If your Mg was as old as your oxidizers, it has probably completely oxidized in storage


The Mg is a few months old and was dark grey so it wasn't completely oxidised. If it was completely oxidised it would be white because MgO is white.



3 minutes ago I tried igniting the KCLO3/C mix. It burned but very slow and only a part of the pile burned away. The rest of the pile remained. I also mixed the KCLO3 with sulfur and it burned good (I know that chlorates and sulfur should not be mixed)

DeAdFX - 8-7-2006 at 14:17

Quote:
Originally posted by 12AX7
FYI, I've never had good luck igniting loose KClO3 and MgAl powder I made myself. Explodes just fine with charcoal and confinement, go figure.

Tim


I find Mg strips + powdered Al/KClO3 easy to ignite but Al/KClO3 impossible...

Zinc... If you have trouble getting KClO3/Mg to ignite then you should consider pruchasing/acquiring fresh batches of both chemicals.

nitro-genes - 8-7-2006 at 14:56

Could be the "fineness" of your Mg, although when it is a dark grey powder it should be fine enough. Another possibility is that it is heavily coated somehow, inhibiting the reaction...

You can test your Mg powder by adding a little conc. NaOH solution to a VERY SMALL amount of the Mg powder. If the mix immediately starts to boil and evolve a lot of heat, leaving no impurities behind in the solution when the reaction subsides it is unlikely that it is coated or oxidised somehow....

If you doubt the potassium chlorate, you could add a drop of conc. sulferic acid to a small pile of it. If is starts to make small popping and hissing sounds and evolve chlorine smelling gasses (ClO2) its likely that it at least contains some potassium chlorate...

12AX7 - 8-7-2006 at 19:01

NaOH and Mg??? Al sure, but, I'm confused.

Acid will certainly do to make either into a voluminous, bubbly, hot, corrosive mess (and especially with copper ions present)! :P

Tim

Zinc - 8-7-2006 at 23:02

Quote:
Originally posted by nitro-genes Another possibility is that it is heavily coated somehow, inhibiting the reaction...

If you doubt the potassium chlorate, you could add a drop of conc. sulferic acid to a small pile of it. If is starts to make small popping and hissing sounds and evolve chlorine smelling gasses (ClO2) its likely that it at least contains some potassium chlorate...



I mixed some KCLO3 and sugar and to the mixture i added a few drops of conc.H2SO4. When a drop would hit the pile a "ssssssss" sound would be heared and the place where the drop landed would be charred but it would not ignite.


I also tested the Mg in a mixture of it with KMnO4. I ignited it with a propane/butane torch and it burned very quickly.

Zinc - 9-7-2006 at 12:07

20 minutes ago I tried to light a mixture of KBrO3 and activated carbon with a magnesium ribbon. Unfortunatly the mixture didn't burn. I am sure that the KBrO3 is KBrO3. I heated it until it decomposed to KBr and oxygen and the I added the potassium bromide to conc. H2SO4 and fumes of HBr were evolved. Also the H2SO4 turned red from a small quantity of bromine that was evolved. Anyway it seems that I must aquire some new KBrO3 and KClO3 but I am still want to know why the mixtures woul'd not burn. The reactants were wery fine and toroughly mixed. The KClO3 and KBrO3 were very old (20-30 years) bute never opened before abd were sealed very well. So do KBrO3 and KClO3 have a limited shelf life?

woelen - 9-7-2006 at 23:05

I have KClO3 of 25 years old, it was opened up before many times and it still is VERY active. On mixing with red P it explodes, simply by rubbing it with a little stick. Adding H2SO4 results in formation of yellow ClO2 and mixing it with sulphur gives a very sensitive and brightly buring mix.

As far as I know, both KClO3 and KBrO3 have unlimited shelf life, provided they are stored in a dry place.

The KBrO3 you have may be a mix of KBr and KBrO3 in a 5 : 1 molar ratio. Such a mix is quite common, because it provides a very convenient way of making bromine in acidic aqueous solution, simply by adding the solid to it. Try adding some of your solid to dilute sulphuric acid. If you get copious amounts of bromine, then your chemical indeed is a mix of KBrO3 and KBr. If it was sold as such, then of course it also must be on the label.

KClO3/Sucrose/H2SO4

MadHatter - 10-7-2006 at 06:17

Sounds like there's something wrong with the KClO3. A drop of concentrated sulphuric acid
placed on a pile of KClO3/sugar should cause that mixture to flare up and burn.

Zinc - 10-7-2006 at 12:10

Quote:
Originally posted by woelen
The KBrO3 you have may be a mix of KBr and KBrO3 in a 5 : 1 molar ratio. Such a mix is quite common, because it provides a very convenient way of making bromine in acidic aqueous solution, simply by adding the solid to it. Try adding some of your solid to dilute sulphuric acid. If you get copious amounts of bromine, then your chemical indeed is a mix of KBrO3 and KBr. If it was sold as such, then of course it also must be on the label.


To 30 ml of dilute sulfuric acid (battery acid) I added a small spoon of of KBrO3. the KBrO3 just dissolved. No bromine was evolved. Also no other gas was evolved. So it seems that it is pure potassium bromate.

garage chemist - 10-7-2006 at 12:32

Seems like there's something wrong with your mixing.
You have to powder both components separately with mortar and pestle, until they are as fine as dust. Then you can mix them by shaking together in a film can.

Also, what mixing ratios did you use? You have to weigh the components.

Also, activated carbon is absolutely useless for pyrotechnics. It doesn't burn when mixed with oxidisers!

Zinc - 10-7-2006 at 13:10

Quote:
Originally posted by garage chemist
Seems like there's something wrong with your mixing.
You have to powder both components separately with mortar and pestle, until they are as fine as dust. Then you can mix them by shaking together in a film can.

Also, what mixing ratios did you use? You have to weigh the components.

Also, activated carbon is absolutely useless for pyrotechnics. It doesn't burn when mixed with oxidisers!



I powder the reactants by putting them on a paper and pressing them hard with a spoon until they are fine as flour.
I mix them via the diaper method.

For ratios I dont know. I never measure anything. Every pyrotehnic mixture I have ever made in my life was mixed with out any standard ratios but that method has never failed me. Some mixtures were good and some not but no mixture has ever failed to ignite when made by this method so I doubt that something is wrong with my mixing.

About the activated carbon I agree. I once mixed it with KMnO4 and it burned very slow and a lot of solid residue was left.

woelen - 11-7-2006 at 01:26

Quote:
Originally posted by Zinc

To 30 ml of dilute sulfuric acid (battery acid) I added a small spoon of of KBrO3. the KBrO3 just dissolved. No bromine was evolved. Also no other gas was evolved. So it seems that it is pure potassium bromate.

Good, now we for sure know it is not a mix of KBr and KBrO3. This test is not 100% conclusive. It could be pure KBrO3, or pure KBr. Now add some of the solid to conc. HCl (or add some NaCl to your solution in battery acid). If you get production of gas (chlorine) and/or creation of bromine (yellow or even red color of liquid), then you have pure KBrO3, otherwise you have pure KBr.

woelen - 11-7-2006 at 01:36

Zinc, after reading all things over again, I have the strong impression that you have received pure KCl and pure KBr. These compounds are called "kalium chloratum" and "kalium bromatum" in pharmacies language, which was not uncommon for chemicals 30 years ago. This is VERY misleading, because these names stand for the chloride and bromide, and NOT for the chlorate and bromate.

All the hissing and fizzling you have with H2SO4 simply is formation of HCl and HBr. With the bromide you have a side reaction, where some bromine is formed, due to the oxidizing properties of conc. H2SO4. The charring of the sugar, also is the action of H2SO4 on sugar. I did a test of adding some H2SO4 to my KClO3. It forms a red/orange drop and yellow fumes of ClO2 are emitted. When I added some sugar to this, then it exploded with a high pitched PENG :o. This is quite different from what you have, just charring of the sugar!

So, I'm afraid I have to disappoint you, but I really think you have pure KCl and pure KBr.

[Edited on 11-7-06 by woelen]

Zinc - 11-7-2006 at 02:56

Quote:
Originally posted by woelen
Zinc, after reading all things over again, I have the strong impression that you have received pure KCl and pure KBr. These compounds are called "kalium chloratum" and "kalium bromatum" in pharmacies language, which was not uncommon for chemicals 30 years ago. This is VERY misleading, because these names stand for the chloride and bromide, and NOT for the chlorate and bromate.

So, I'm afraid I have to disappoint you, but I really think you have pure KCl and pure KBr.


I don't think so. When I mixed the potassium chlorate with sulfur (a dangerous thing to do) it burned good so it can't be KCl. Sadly it only burned good with sulfur:(. And about the potassium bromate when I added the potassium bromate to dilute sulfuric acid it only dissolved. No HBr was evolved. I also heated the KBrO3 until it decomposed to potassium bromide and oxygen. Then I added the KBr to conc. H2SO4 and fumes of HBr were evolved. Also the sulfuric acid turned red from a small amount of bromine that was also evolved. From this I conclude that I have KBrO3 and KClO3 and not KBr and KCL.

You are right about the old pharmacy names. Once in school I have seen a bottle and on the lable it wrote ammonium chloratum. I then said "No way. This can't be ammonium chlorate. It is a very sensitive explosive." Afther that I saw the formula NH4Cl under the name.

Edit
Quote:
Originally posted by woelen
Now add some of the solid to conc. HCl (or add some NaCl to your solution in battery acid). If you get production of gas (chlorine) and/or creation of bromine (yellow or even red color of liquid), then you have pure KBrO3, otherwise you have pure KBr.


I added some NaCl to the battery acid and after that I added some of the supposed KBrO3. Nothing happened. The supposed KBrO3 only dissolved. I still think that I have KBrO3 and not KBr. When I added the KBrO3 to dilute H2SO4 it would just dissolve but when I heated the KBrO3 until it would decompose to oxygen and KBr and added the potassium bromide to dilute sulfuric acid fumes of HBr were evolved. Also the H2SO4 turned red from a small amount of bromine that was also evolved.

[Edited on 11-7-2006 by Zinc]

chromium - 11-7-2006 at 04:14

I have one more idea how to distinguish between KBr and KBrO3. KBrO3 is much less soluble in water: 6.9g/100ml @ 20C ; 3.0g/100ml @ 0C. KBr: 65.2 g/100ml @20C ; 53.5 g/100ml @ 0C

woelen - 11-7-2006 at 04:14

I have severe doubts on your KBrO3. I have KBrO3 and I added some to H2SO4. Added to dilute H2SO4, it just dissolves, but KBr also just dissolves and no fumes of whatever type are evolved. When I add solid KBrO3 is added to concentrated H2SO4 then a VERY violent reaction starts, producing oxygen and bromine.

Pure KBr, besides HCl, also gives bromine (and SO2) with conc. H2SO4, because of the oxidizing properties of conc. H2SO4.

And, when you have KBrO3, even only at low percentage, then adding this to a NaCl/H2SO4 solution definitely would give a fairly violent reaction, in which chlorine and brominechloride are formed. I did the experiment by adding solid KBrO3 to 15% HCl. When this is done, then there is strong effervescence at the granules of KBrO3. The fizzling is quite strong. The bubbles are chlorine, but also contain bromine. The color is yellow. The liquid also becomes yellow (*piss color*). When you could not even see a faint yellow color, then I'm very sure that your stuff is not KBrO3.

You write that you heated the KBrO3, until it decomposes, giving oxygen. Did you test the presence of oxygen with a glowing spint?

If you really want to be sure, and you have conc. HCl, then add a spatula full of both of your chems to that.

KClO3 will give a very intensely colored deep yellow gas, and the liquid becomes deep yellow. Even with a small amount of KClO3 you will see that color. Pictures of what you should observe are here:

http://woelen.scheikunde.net/science/chem/exps/clo2/index.ht...


KBrO3 will result in violent bubbling, formation of chlorine gas, and the liquid will turn piss yellow. Unmistakenly!

If your liquid remains colorless and no bubbles are observed, then 100% sure you have no KClO3 and KBrO3.

If you don't have concentrated HCl, then you could try adding a lot of finely crunched table salt to 30% H2SO4 and use that instead of conc. HCl.

[Edited on 11-7-06 by woelen]

Zinc - 11-7-2006 at 06:02

Quote:
Originally posted by woelen I have KBrO3 and I added some to H2SO4. Added to dilute H2SO4, it just dissolves, but KBr also just dissolves and no fumes of whatever type are evolved. When I add solid KBrO3 is added to concentrated H2SO4 then a VERY violent reaction starts, producing oxygen and bromine.


When I added the KBr made by the decomposition of KBrO3 I added it to conc.H2SO4 and not to dilute H2SO4. I will add it to dilute H2SO4 and post the resluts.
Quote:
Originally posted by woelen
And, when you have KBrO3, even only at low percentage, then adding this to a NaCl/H2SO4 solution definitely would give a fairly violent reaction, in which chlorine and brominechloride are formed.


Nothing happened. The KBrO3 just dissolved. Do you mean a mixture of NaCl and conc.H2SO4 or a mixture of NaCl and dilute H2SO4? I added it to a mixture of dilute H2SO4 and NaCl.
Quote:
Originally posted by woelen
I did the experiment by adding solid KBrO3 to 15% HCl. When this is done, then there is strong effervescence at the granules of KBrO3. The fizzling is quite strong. The bubbles are chlorine, but also contain bromine. The color is yellow. The liquid also becomes yellow (*piss color*). When you could not even see a faint yellow color, then I'm very sure that your stuff is not KBrO3.


I added a small spon of KBrO3 to 19% HCl and nothing happened. The KBrO3 just dissolved.
Quote:
Originally posted by woelen
You write that you heated the KBrO3, until it decomposes, giving oxygen. Did you test the presence of oxygen with a glowing spint?


The glowing splint didn't ignite. It even stopped to glow.:o
Also in my previous posts I have forgot to mention that when I was heating the potassium bromate when it decomposed (the cracking sound stopped) the christals melted.

I also added the KBrO3 to conc.H2SO4 and a violent reaction occured. The H2SO4 turned red and fumes of bromine were evolved. Also a small amount of "dilute" white fumes was evolved.

[Edited on 11-7-2006 by Zinc]

[Edited on 11-7-2006 by Zinc]

Zinc - 11-7-2006 at 06:42

Quote:
Originally posted by Zinc
When I added the KBr made by the decomposition of KBrO3 I added it to conc.H2SO4 and not to dilute H2SO4. I will add it to dilute H2SO4 and post the resluts.


I tried it 10 minutes ago. It dissolved and a smell simillar to the smell of HBr appeared. No visible fumes were evolved and no bubling occured.

Unfortunatly I can't more experiment with potassium chlorate:(. I ran out of it and noticed it today when I took the botlte and saw it is empty.

woelen - 11-7-2006 at 11:49

OK, now I'm 100% sure you have no KBrO3, you have KBr :(.

The crackling sound on heating is due to crystals, breaking apart. Even simple table salt may give crackling noise on strong heating.

I indeed meant adding KBrO3 to dilute H2SO4/NaCl. You did that and nothing happened, just dissolving. Even if your stuff contained a few percent of KBrO3, then the liquid would turn yellow or even red/orange.

Finally, you added it to 19% HCl. My KBrO3 gives a very violent bubbling reaction with this, similar to adding Na2CO3 to 19% HCl, except that the gas evolved is not CO2, but Cl2.

Zinc - 11-7-2006 at 12:52

It was probably a old pharmacy name. They called ammonium chloride ammonium chloratum so probably they called potassium bromide potassium bromatum.
I really hate those old pharmacy names. They are very misleading.

About the KClO3 I don't know. Probbably it was potassium chlorate since it burned good with sulfur. Sadly it burned good only with sulfur. Do you know the reason why it burned good only with sulfur? It didn't burn with Mg and with activated carbon it burned very slow and only a part of the pile would burn away. The rest of the pile remained. Unfortunatly I can't experiment more with KClO3 since I have run out of it.

woelen - 11-7-2006 at 13:03

The only reason I can think of with the KClO3 failing to burn with Mg is that it is not mixed well enough. Normally, it definitely reacts violently, but the metal must be finely powdered. Not granules of 0.1 mm size, but much smaller, such that they seem to float in the air, when they are gently breathed at.

Yes, with the KBr I can imagine that the person, who gave it to you was mislead by the name of the compound. You can, however, fairly easily make KBrO3 from KBr by means of electrolysis. I have done that (in fact, that is my source of KBrO3), and garage chemist also has done that. Fairly recently, there was a thread about that, just search for "bromate", or something like that. Garage chemist used a tiny amount of a dichromate, to make the electrolysis cell more efficient and that indeed is a good idea. If you have some, give it a try, but without, it also works, but with much lower efficiency. Garage chemist obtained really white KBrO3, mine is a little yellow, probably due to trapped traces of Br2. It works very well though, despite the slight coloration of the chemical.

Zinc - 11-7-2006 at 13:19

Quote:
Originally posted by woelen
Normally, it definitely reacts violently, but the metal must be finely powdered. Not granules of 0.1 mm size, but much smaller, such that they seem to float in the air, when they are gently breathed at.


You are probbably right. My magnesium was not airfloat. Unfortunatly I have not a ball mill.

But still I don't understant why it didn't burn when I mixed it with sugar and added a drop of conc.H2SO4. The place where the drop landed charred and a "ssssss"sound was heard but the mixture didn't ignite.

A word of warning to everyone who is working with bromates. They are carcinogenic. http://en.wikipedia.org/wiki/Bromate

BTW you have a very good web page woelen.

[Edited on 11-7-2006 by Zinc]

Zinc - 13-7-2006 at 12:56

Today my chemistry teacher gave me some new old (20-30 years) NaClO3 so I can start experimenting with it. I also got some potassium nitrate (20-30 years old) and some new potassium nitrate so I can also test it.

I mixed some sodium chlorate woth suggar and to the mixture I added some conc.H2SO4. Nothing happened. Even the suggar didnt charr so I think something is wrong with the H2SO4. I made the conc.H2SO4 by boiling down battery acid until thick fumes appeared (SO3). I added the sulfuric acid to the mixture of sodium chlorate and suggar about 30 min. after I made it. The conc.H2SO4 could absorb some water during that time but I doubt that because most of the time the sulfuric acid was in a baker that was sealed by 3-4 layers of toilet paper and abowe the toilet paper was a brick. I opened the conc.H2SO4 5-7 minutes before I added it to the mixture.

When I test the KNO3 I will post the results.

12AX7 - 13-7-2006 at 13:30

NaClO3 is rather hygroscopic. Especially this time of the year, in the midwest anyway.

Tim

woelen - 14-7-2006 at 01:03

Try adding the supposed NaClO3 to your 19% HCl. You should obtain the yellow gas and bubbles as they are on my website (see a few posts back). If the liquid remains colorless and no yellow gas at all is formed, then it is not NaClO3.

Zinc - 14-7-2006 at 08:15

I mixed the NaClO3 with sulfur and tried to ignite it with a propane/butane torch. The mix did not ignite but some crackling sound appeared and lasted for about 30 seconds after I stopped heating the mix and cristals of the NaClO3 were jumping.
Quote:
Originally posted by woelen
Try adding the supposed NaClO3 to your 19% HCl. You should obtain the yellow gas and bubbles as they are on my website (see a few posts back). If the liquid remains colorless and no yellow gas at all is formed, then it is not NaClO3.


I tried it. Nothing happened. Only a part of the cristals just dissolved. I do not thing that the NaClO3 was mislabeled since I saw the formula on the bottle from wich I got the NaClO3. Altough it is possible that something else was in the bottle since I also got a empty bottle of chloroform (my chemistry teacher gave me besides chemicals a lot of empty bottles and glassware and a gas mask) and a solid chunk of something was in it. She would often refill the bottles after their original content was spend and she would not put a new label on the bottle.

woelen - 14-7-2006 at 10:32

Well, then it is not NaClO3. Believe me, NaClO3 reacts with HCl and this reaction is VERY sensitive. The compound ClO2 has a really intense color.
Quote:
She would often refill the bottles after their original content was spend and she would not put a new label on the bottle.

If this really is true, then I think she is a bad teacher, despite the fact that she is so kind to give you many interesting items. It is a VERY VERY bad practice if bottles are refilled with chemicals and the labels are not updated or exchanged. I can hardly believe this from a chemistry teacher :o.

But again, the chemical you obtained is not what she said. The best thing you can do is ask her about that and show her this 'weird' thread. Maybe she is able to help you and tell you really what is in that bottle. Otherwise you need to do some qualitative analysis.

Zinc - 15-7-2006 at 03:00

Quote:
Originally posted by Zinc
She would often refill the bottles after their original content was spend and she would not put a new label on the bottle.


I exaggerated when I said that (I was very angry at her at that time for doing that). She did that only 2-3 times and probbably she just forgot to put a new label on the bottles. She works in that school for about 30 years and most of the chemicals are about that old so she could do that 30 years ago ( she did that only a t the old bottles). The thing that she reffiled the bottles and forgot to put a new label on the bottles is not really important (it is to me and my friend) because 95% of the chemicals in the cabinet are not used in class anymore and will probbably be thrown away in the near future.

Today I will test the old and new potassium nitrate and I will post the results.

Zinc - 2-10-2006 at 08:13

Quote:
Originally posted by Zinc
Today I will test the old and new potassium nitrate and I will post the results.


I tested both of them and none of them burned with sulfur. I ground them seperatly with a mortar and pestele and mixed them by shaking them in a film can.
Do you know why?