woelen
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Funny experiment with purple and yellow smoke
If you are looking for colored smoke, then this experiment may be a cool one. Unfortunately, one of the chemicals is not really cheap (KIO4), but also
not extremely expensive.
I was a little bored and was trying different oxidizer/reductor combinations, and this one was really neat, actually so nice that it justified
devoting an entire webpage to it.
http://woelen.homescience.net/science/chem/exps/colored_smok...
If you have access to ammonium thiocyanate and a periodate, then you should definitely try this. It even looks better when you see this in reality.
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: fixed
external link(s)]
[Edited on 7.1.14 by bfesser]
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Antwain
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Pretty sure thats got absolutely nothing to do with I3-, not being in any kind of solution and all. The purple being iodine sounds like it could be
right. If the yellow stuff was sulfur, although I cant see why you wouldnt get oxides, It would slowly react in basic *solution* but not in the solid
state
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Ozone
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Very cool Woelen! You always seem to find these goodies.
Perhaps fine ammonium iodide (i'm thinking it looks very much like yellow ammonium chloride "smoke") with sulfur particles attached?
Just a guess,
Neat!
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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mrjeffy321
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Interesting.
The colored smoke does not look too dissimilar to that produced by the reaction between Copper(II) Chloride and Aluminum which also produces some
yellow and purple –ish smoke.
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The_Davster
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Nice as always, looks like sulfur and Iodine. But the reactivity does not seem like sulfur from your page!
I wonder if there could be some sort of sulfur iodides, or perhaps some sort of sulfur-iodine oxy compound, if these compounds exist, in the smoke.
It could explain the condensation of the red liquid. (I may very well be waay off here).
Are you able to take the ph of the solution after dissolving the smoke in water?
The brown colour to me seems indicative of HI decomposing to iodine, but if that were happening, peroxide should make more of it? But perhaps there
was not enough in the smoke?
The sodium sulfite again seems to indicate iodine being reduced to iodide.
Are you sure that the iodine fumes turns yellow?, iodine fumes dissapate very quick, could it have just been obscuring the orange smoke, and then it
dissapates leaving the orange? I once released several grams of iodine vapour in a room accidently, it was billowing out of the beaker, and was
bright purple at the mouth, but around 20cm from the beaker the iodine fumes were below visible concentration in air.
(I was trying to directly substitute phenol with a IO group, something analogous to a runaway nitration occured I think)
I am curious to see other sulfur/iodine compound solid state reactions, to eliminate various elements from the smoke and see if it retains the same
character. I will try iodine pentoxide (anhydride of iodic acid ) and sulfur!
EDIT: Oops, yeah, iodic acid, not periodic acid anhydride.
[Edited on 16-8-2007 by The_Davster]
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The_Davster
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Hmm I was not lazy tonight and just tried it.
I2O5 ground gently with sulfur and lit with a match. Gives a very similar smoke to what I see in your pictures. I suppose that can kinda be made out
from my pictures?
hmm I think I need advice for making good movies with my video setting on my digital camera...Bad lighting?
[Edited on 15-8-2007 by The_Davster]
[Edited on 15-8-2007 by The_Davster]
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woelen
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@Antwain: If the yellow color is not due to I3(-), then what do you think it could be? I am inclined to think of I3(-), especially because of the
darkening of the solution, when acid is added and the disappearing of the color, when sulfite is added.
I must admit, however, that the situation for the ashes is different. I repeated the experiment with KBrO3 as oxidizer, instead of KIO4. This results
in a very similar outcome, except that the smoke is white, but the ashes still are bright yellow. With KClO3 as oxidizer, the ashes also are yellow,
and again white smoke is produced. I did not yet try with KIO3 and KClO4, but I expect the reaction with KIO3 to be slow or even not going at all.
With KClO4 I expect similar results as with KClO3, except that the mix probably is hard to get going (or even impossible to get going, KClO4-mix is
not that easily ignited).
So, yellow smoke only is obtained with iodine in the oxidizer (see also experiments of The_Davster), but the ashes are yellow with other oxidizers as
well. So, it could be that the yellow color in the smoke is due to some other compound than the yellow color in the ashes. The yellow ashes are
insoluble, also for KBrO3 and KClO3 as oxidizer, while the yellow smoke really is soluble.
@The_Davster: Your experiment with I2O5 is very interesting and it is good to see that this gives similar results. I unfortunately don't have I2O5,
but I do have HIO3. I could try to dehydrate some of this by careful heating to 200 C or so. Btw, I2O5 is not the anhydride of periodic acid, but it
is the anhydride of iodic acid. The anhydride of periodic acid is I2O7, but I have serious doubts about the existence of I2O7.
I'll certainly perform more experiments with this reaction in different variations. Next weekend I have time for that. I also will try the pH-test on
the smoke, dissolved in water. That is an interesting test also. I'll come back on this when I have done the additional experiments, and otherwise,
please remind me of that.
The red droplets on the bottom of the glass jar probably are just water, with something dissolved in it. As i wrote at the end of the webpage, the
main reaction of the redox reaction between KIO4 and NH4SCN probably produces quite some water and this may form droplets with other products in the
smoke.
If I find this kind of remarkable reactions, then I always have a deep desire to find out what really happens  . The reaction in itself is funny and cool, but things become much better if I understand what is going on. This is
especially interesting, because the reagents used in this reaction are so simple.
|----------------------- OFFTOPIC RANT ON VIDEO -----------------------------
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v
If you want to make a good video of the experiment, then you should do three things:
1) Create a neutral background. In my video, I have a big sheet of artists paper behind the scene, which I want to record. In your video there is too
much irrelevant detail, and the color of the smoke is hard to tell, because of the dark and colored background.
2) Use good lighting. I use a dark room incandescent light bulb, which normally is put in an enlarger. These give whiter light than normal tungsten
bulbs, while still having a good spectral distribution. In my situation, I now still feed this lamp with 230 V AC, but I am working on a DC voltage
source. The flickering of 50 Hz interferes with my digital camera sampling rate of 30 Hz or 60 Hz and that is very annoying. I can get rid of this
with post-processing software, but this is very cumbersome. You can use a normal tungsten bulb, but then you need a color correction because the
images have a yellow hue. Maybe your camera has a setting for inside tungsten lighting, which compensates for the yellow hue?
3) Assure that you never are between the camera and the scene you want to record. Either use long sticks, or arrange things, such that you can
approach from behind. In your video, there are frames, where your hand almost fills 50% of the image area.
Personally, I must say, that when I make a video of a chemical reaction, it takes me more time to set up all things for the video (lighting, camera on
tripod, precise location where reaction is performed, neutral background) than for the experiment itself. Usually I also do a few recordings, without
the reaction, just to get an idea if everything is located well and the composition, lighting and sharpness of the image looks good. Only when all is
OK, I do the actual experiment.
[Edited on 16-8-07 by woelen]
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Antwain
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I cant be sure that it isn't I3-, I just have a gut feeling that I2 isn't going to form adducts with other chemicals in the solid state. As
The-Davster suggests, the iodine may just be dissipating, making it invisible. If this were the case, perhaps something is oxidising from not very
highly coloured to yellow. Or cooling... some things change colour depending on temperature. You could try heating some of the yellow stuff and seeing
what you get.
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The_Davster
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Soon I will try the reaction in glass, and try to condense the smoke.
I also will make SO2 and introduce iodine vapours to it.
(and try to may my videos better)
Again, just theorizing, but what I think/guess is happening:
I2O5+S --> I2 +SO2+SO3(or change the stoichiometry to have it just go to SO2)
I2+SO2-->SO2I2 (the later hydroysis and redox reactions may support this?)
I am going to have to agree with Antwain, I do not think I3- can be formed in such a reaction. That would require airborne iodides initially, as well
as iodine vapour. And I also am not sure if I3- exists in the solid state?
EDIT: Wow I had no idea I could post pictures as an edit! How long has that been on for?!
But anyway, I tried the reaction of SO2 and Iodine today.
I used acidified bisulfite as the SO2 source in the bottom of a wide testtube to alow SO2 to fill the tube. I then melted some iodine in a vial,
sucked it up in a hot pipette keeping it molten, and let a drop of the liquid iodine fume on the end of the pipette in the SO2 environment. The first
drop fell onto the side the the testtube. As can be seen in the picture, other than the purple solidified iodine on the testtube, an orangy solid did
collect on the sides of the testtube.
(PS the colours are just fine, the wall really is that colour)
[Edited on 16-8-2007 by The_Davster]
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woelen
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I also did some further testing. I repeated the reacton with KIO4 and NH4SCN under the glass jar and again collected the yellow smoke. This time I
dissolved the smoke in less water. This results in a fairly pale yellow solution, which is very slightly turbid. I poured this yellow solution in a
narrow long test tube and let this stand vertically, stoppered for 6 hours or so. No precipitate at all after that time and still the liquid is only
very slightly turbid, an occasional observer would say it is a clear light yellow liquid.
Based on this observation, I conclude that this yellow material cannot be sulphur, otherwise the liquid should be very turbid or a decent amount of
yellow precipitate should be formed.
I also measured the pH, using a paper indicator for multiple pH's. The pH measurement is quite uncertain, but one thing it makes clear, the liquid is
close to neutral (seems to be something like 5 or so). Adding a pinch of NaHCO3 also does not result in bubbling.
When the light yellow solution is acidified with a few drops of 20% H2SO4, then it becomes fairly deep yellow/brown and it remains clear (just the
very faint opacity of the original solution).
--------------------------------------------------------------------
I'll try to comment on the ideas of The_Davster. I myself did not yet try the I2O5/S experiment, because it proved to be hard to make I2O5 from HIO3.
The HIO3 makes loud cracking noise when heated. The crystals are swirled around, not by real explosion, but by means of strong internal strain and
cracking. Really annoying. Even little crunched pieces are jumping around all over the place. Heating must be done in a closed vessel.
The first step of The_Davster reaction seems very reasonable to me. I also would expect I2 and SO2 (and possibly some SO3).
The second step of SO2I2 seems very unlikely to me. In my books I cannot find anything about such a substance.
The experiment of adding iodine to SO2 is neat, but it is not conclusive. Still, the brown material can be I3(-) or higher polyiodides. I3(-) does
exists in the solid state (e.g. CsI3 is a fairly stable salt, even CsBr3 is, which I made myself (picture is on my website)).
Did you make the SO2 from wet NaHSO3 or wet Na2S2O5? The SO2 then also will contain quite some water vapor. As far as I know, SO2 does not react with
iodine, unless water is present. In the presence of water they react as follows:
2H2O + SO2 + I2 <--> H2SO4 + 2HI
H2SO4 and HI are hygroscopic and will attract more water, getting dissolved. This liquid can pick up iodine:
I(-) + I2 --> I3(-), this has a brown/orange color in thin layers. When contaminated with more iodine, even higher polyiodides can be formed, and
the stuff becomes dark brown in such cases.
Iodide also forms an adduct with sulphur dioxide:
I(-) + nSO2 ---> [I.nSO2](-).
This adduct has an intense yellow color. You can make this adduct as follows:
Dissolve some bisulfite in dilute H2SO4 or HCl (10% or so). You should have a nice smell of SO2.
Add some KI or NaI to this. The liquid becomes deep yellow as the iodide dissolves. I do not believe, however, that this adduct is causing the yellow
color of the smoke.
An interesting experiment would be to repeat the experiment under dry conditions. Add a few drops of concentrated H2SO4 to solid Na2S2O5, Na2SO3 or
NaHSO3. This gives dry SO2, some heating may be needed. To this dry SO2 again add some iodine vapor. Assure that no H2SO4 sticks to the walls of the
test tube with SO2, because that also gives rise to brown stuff with iodides. I myself do not expect any reaction in this case.
I of course did not give any explanation of the yellow color of the smoke, but I just want to be sure that the presence of water vapor does not have
too strong influence on the outcome of the experiments.
More experimenting from my side will follow this weekend. This subject is broadening, but it is very interesting . I'll try:
- dry SO2 with I2
- I2O5 with S (if I can make I2O5 safely)
- KIO4 with S, instead of NH4SCN
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Antwain
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I am going to try to make me some HIO3 today, as soon as the sun comes up in an hour even, and with any luck I can repeat your reaction. I don't have
ammonium thiocyanate, but I have potassium. I may try to make the ammonium salt, or just go with KSCN. Even this may tell us something interesting,
such as whether it works with both potassium salts...
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woelen
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I did the experiments of The_Davster.
I2O5 + NH4SCN gives a result very similar to what my video shows. So, the K is not necessary for the yellow smoke.
KIO4 + S gives no smoke at all. It burns with a small blue/purple flame, giving off a mix of gaseous iodine and sulphur dioxide. The smell of sulphur
dioxide is very strong from this mix. It burns absolutely cleanly, really no smoke at all. I tried different ratios (molar ratio KIO4 : S = 1 : 2,
KIO4 : S = 1 : 4 and KIO4 : S = 1 : 1.5), but all of them were without smoke.
I2O5 + S does not burn at all. It gives iodine vapor on heating in a flame, and the sulphur melts and may start burning. Again, different ratios were
tried, but none of them burnt.
From my experiments, I can conclude that thiocyanate is required for getting the yellow smoke. Using sulphur, the results are very different.
The_Davster, I'm really surprised that you could get your S/I2O5 mix burning. I never obtained any flame from this mix, just decomposition of the I2O5
and melting (and subsequent slow burning) of the sulphur.
Antwain, I really would like to know how your experiment with HIO3 (I2O5 by heating this?) and KSCN is going. I have some NaSCN, but this is VERY wet
(like a paste, due to absorbed water), and hence it is useless for this type of experiments.
More follows on this subject...
EDIT: I modified the webpage of this experiment. Based on further tests I did, and on the responses of The_Davster and Antwain, I indeed have to
conclude that I3(-) does not play a role in this experiment. I now simply have no explanation for the yellow compound(s), formed in this experiment.
More research is needed on that.
I also added two videos, one of them being a slow-motion. The slow-motion video I find very nice, because it shows how the smoke develops over time in
much more detail. The videos can be accessed from the webpage, near the link of the first video.
[Edited on 18-8-07 by woelen]
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The_Davster
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I tried the I2O5/S reaction in a small microscale distillation setup. Strangly, when the mix reacted when heated by flame only iodine vapour was
given off. No orange smoke...
I then was puzzled so I tried the reaction on a spatula again, heating it from below with a burner flame. Again, no orange smoke. I then took some of the I2O5/S mix, and put a just lit match into it,this time
there was iodine vapour as well as the orange smoke.
This limits my ability to produce smoke in a collectible manner.
Unless I use a fuse or something and build a little smoke bomb with I2O5/S, and light it and put it in a distillation apparatus. But the temp shock
and pressures would likely break the glass.
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woelen
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I have the impression that there is something in the match, which causes the smoke. I only would trust results, where the mix is heated without any
chemical substance being immersed in the mix. Good to see that your results are similar to mine.
I also finally did the SO2/I2 experiment. I did the following:
Take 500 mg of K2S2O5 and put this in a short and wide test tube.
Add a single drop of water.
Add appr. 1 ml of H2SO4 (96%) and immediately put a stopper with a rubber tube in it on the test tube.
This results in formation of lots of SO2 and the other end of the rubber tube was put in a dry and clean 100 ml erlenmeyer.
In this way, I collected around 100 ml of SO2.
To the erlenmeyer with SO2 in it, quickly add a few crystals of iodine and cover the erlenmeyer with a watch glass.
Heat the bottom of the erlenmeyer above a flame. This results in formation of a lot of purple vapor and many tiny iodine crytals are formed on cooler
places of the erlenmeyer.
The iodine does not react. By heating, the material is moved around, but it does not react.
When a single drop of water is added, then soon all iodine, which settled at the glass walls seems to liquefy and becomes brown. So, indeed, water is
required for the reaction as well. Adding a little bit more water and shaking results in dissolving of all iodine and the liquid becomes pale yellow
and clear, while there still is a very strong (almost unbearable) stench of SO2. The pale yellow color is due to formation of the adduct [I.nSO2](-).
No evidence of strange orange/yellow solids, or sulphur/iodine/oxygen species other than the yellow adduct, mentioned above.
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Antwain
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Sorry, its been a long time. I have isolated but not dried/ removed nitric acid from several grams of iodic acid. I am waiting until my other reaction
is completed, which should yield several 10s of grams... hopefully. The synthesis has been a comedy of errors including me breaking a water condenser
and having to recover 40g of iodine (messy and smelly, and made me sick, I think), plus i have just had uni tests but 2 weeks of holidays after
tomorrow so I will get around to trying this.
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woelen
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Antwain, the life of a chemist, especially a home chemist, is not easy at all at times . But I appreciate that you try to make iodic acid and try to repeat this experiment.
I have done some thinking about the yellow material, formed in the reaction. I've also taken into account your remarks about I3(-) and now I've
conclusively shown that you are right. I have been speculating on controlled oxidation of thiocyanate and thinking in this direction seems quite
fruitful. I definitely have shown that the yellow material is not a compound of iodine. What it is, however, still is not clear.
I did an experiment, attempting to oxidize thiocyanate in a controlled way. I prepared 10 ml or so of a solution of approximately 1 mol/l of NaSCN and
electrolysed this with a DC current of approximately 1 A, using two carbon electrodes. At the cathode, gas is formed (hydrogen). Initially, at the
anode nothing seems to be formed. No bubbles of gas, no colored compound. After a few minutes, when the liquid has heated up, due to the electrical
current, however, at the bottom of the beaker, a yellow precipitate is formed and also yellow stuff is formed at the anode. Exacly the stuff like I
have in my experiment with periodate and iodic acid ! So, this material also
can be formed with electrolysis of a solution of a thiocyanate!
In the cell, I think the following happens:
cathode: 2H2O + 2e --> 2OH(-) + H2
anode: 2SCN(-) - 2e --> (SCN)2
(SCN)2 is a colorless compound, but it is not stable. It decomposes, and the decomposition most likely gives the yellow compound. I also think now
that in the experiment with the yellow smoke, also first, among other material, (SCN)2 is formed, which quickly turns bright yellow while it
decomposes.
The yellow smoke, which I have dissolved in water, I still have. What first was a clear yellow solution now is a colorless liquid with a yellow
precipitate at the bottom. So, most likely, I was fooled by its appearance and the liquid was not really a solution, but a colloid.
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Antwain
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Hey, not a bad speculation. From F Sherwood Taylor " Thiocyanogen (SCN)2 has been made by the action of bromine on lead thiocyanate in ethereal
solution. I forms colourless crystals. Like oxycyanogen, it resembles a halogen." Just before this it claims that oxycyanogen is formed from iodine on
silver cyanate. Do you know what thiocyanogen decomposes to?
I do have I2O5 now, slightly, very slightly, impure because the second batch was slightly browner than the first... unfortunately I did what one
should never do and mixed them before I knew this  . Anyhow it has to be more than
99% (excluding possible HIO3 impurity) so I will use some of this tomorrow and see what I get. I may also try something like KMnO4 and see what that
does.
Also I only have KSCN, but we shall see if it matters. Also I can make NH4IO3 to have basically the same stuff you used. Btw, It did work with iodate
as well as periodate did it not?
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woelen
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Antwain, great that you could make I2O5 from your starting materials! That's good work!
With I2O5 (and HIO3) it works quite well, just as with KIO4. With KIO3 it hardly works. It just smoulders a little bit, nothing useful. So, it is good
that you have I2O5/HIO3.
I unfortunately don't have KSCN. I only have NH4SCN (dry solid) and a solution of NaSCN. If you have solid KSCN, then check whether it is dry or not.
This stuff is very hygroscopic. Careful drying at 70 C may be necessary. With humid thiocyanate it does not work, you only get smouldering at best
with humid material.
I don't have any idea about the decomposition products of (SCN)2. I can imagine that this on decomposition gives the yellow material. I hope to find a
little more time for experimenting next weekend. In the last electrolysis experiment, I used a solution of NaSCN, but this of course contains
hydroxide after some time of electrolysis. This hydroxide might cause the decomposition of (SCN)2. I want to retry the same electrolysis experiment,
but now with an acidified solution of NaSCN (with a small amount of dilute sulphuric acid), such that the liquid remains acidic. I wonder whether the
yellow stuff will be formed under such conditions. Another experiment will be electrolysis with a salt bridge, such that the anode and cathode are in
different spaces and no mixing in of cathode-stuff occurs at all.
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Antwain
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Didn't manage to do it today It was raining, and I am not sure enough about the
integrity of my power cord to run it through the rain. Also my father's work computer is on the same circuit, and he is even less convinced about me
leaving it out in the rain So tomorrow, perhaps.
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AJKOER
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An interesting thought, per the reaction:
2 H2O + SO2 + I2 <--> H2SO4 + 2 HI
My take is that the reaction proceeds as follows:
I2 + H2O <--> HOI + HI
HOI + SO2 in excess + H2O --> H2SO4 + HI (which parallels Hypochlorous acid, namely, H2SO3 + HOCl --> H2SO4 + HCl )
although I would also expect an iodate based path from:
3 HOI --> 2 HI + HIO3
so, as some authors do (see, for example, "Inorganic Reactions in Water" by Ronald Rich, page 468, where both paths are detailed link http://books.google.com/books?id=Dv_F03cdKPUC&pg=PA468&a... ) without an excess of SO2, the reaction proceeds via HIO3.
Now, purely theoretically cancelling water from both sides and scaling by x:
x HOI + x SO2 in excess --> x SO3 + x HI
and combining with:
HOI + SO2 in excess + H2O --> H2SO4 + HI
(1+x)HOI + (1+x) SO2 in excess + H2O --> H2SO4.xSO3 + (1+x)HI
where per Wikipedia (http://en.wikipedia.org/wiki/Oleum ), Oleum can be described as H2SO4.xSO3 with x being the molar free sulfur trioxide content.
Further, HI + HOI = I2 + H2O, adding (1+x)HI to both sides of the equation and substituting Iodine water:
(1+x) I2 + (1+ x) SO2 in excess + (2 +x) H2O --> H2SO4.xSO3 + 2 (1+x)HI
Or: I2 + SO2 in excess + (2+x)/(1+x) H2O --> 1/(1+x) H2SO4.xSO3 + 2 HI
which appears to suggest that this reaction, with an excess of SO2, under the proper conditions, could produce products resembling Oleum and Hydriodic
acid.
Note, taking x=0 basically gives the reaction cited by Ronald Rich in the reference above.
----------------------------------------------------
With respect to the iodate path, I will re-write the author's reaction as follows:
2 HIO3 + 5 SO2 + 4 H2O --> I2 (s) + 5 H2SO4 (another reference, see http://books.google.com/books?id=PpTi_JAx7PgC&pg=PA586&a... )
Upon cancelling out theoretically four water:
2 HIO3 + 5 SO2 --> I2 (s) + H2SO4.4SO3
implying possibly that the action of SO2 on Iodic acid could form Iodine and an Oleum rich Sulfuric acid.
Even more interesting as:
2 HIO3 --Heat to 200 C in a Stream of Dry Air--> H2O + I2O5 (see http://en.wikipedia.org/wiki/I2o5 )
and removing the last water from both sides implies a possible path to SO3 by the action of Iodine pentoxide on SO2, a completely unreported path, on
which I have doubts. However, there is an interesting similarity to some sources (presented in another thread by myself) suggesting that N2O3 (in
place of I2O5) can act on SO2 in the presence of water vapor, under the right conditions, to form SO3.
[EDIT] After reading this extract at Atomistry.com (link: http://sulphur.atomistry.com/sulphur_trioxide.html ) on SO3, my opinion has changed and is more positive. To quote:
"Sulphur dioxide is easily converted into the trioxide by the action of oxygen and gentle heat. Above 450° C. there is a tendency towards the
formation of an equilibrium mixture of sulphur dioxide and trioxide with oxygen, but below this temperature the amount of dioxide in the equilibrium
mixture is almost inappreciable. It is inadvisable, therefore, to allow the reaction to occur at too high a temperature, but, at the same time, the
temperature must not be too low, otherwise the rate of change will be very slow.
The change has been submitted to careful physico-chemical examination and is found to accord with the usual method of expression,
2SO2 + O2 ⇔ 2SO3,
in agreement with which are the facts that the reaction is termolecular and that increase in pressure greatly favours the formation of trioxide.
The presence of traces of moisture exerts a very considerable favourable effect on the rate of combination of the gases; reaction after drying with
phosphorus pentoxide is relatively sluggish.
Many solid substances are remarkably active in accelerating the change; especial mention may be made of finely divided platinum..... Sugar charcoal
and the oxides of iron, copper, vanadium and arsenic are amongst other substances which possess catalytic power over the reaction, and although they
are weaker catalysts than platinum, the final proportions of dioxide and trioxide in the equilibrium mixture are but little affected by the nature of
the catalyst used. The present commercial process for the manufacture of sulphur trioxide is based on the use of such catalysts."
As Fe2O3 and CuO can facilitate the formation of SO3 from SO2 and O2, especially in the presence of water vapor, why not I2O5, as per this source
(page 584, "A text Book of Inorganic Chemistry" by Anil Kumar De link: http://books.google.com/books?id=PpTi_JAx7PgC&pg=PA584&a... ):
2 I2O5 --Heating--> 5 O2 (g) + 2 I2
so we have an oxide (of Iodine providing opportunity for a surface based reaction ) and oxygen.
Also, Atomistry.com on my N2O3 reference pathway to SO3 states:
"Sulphur trioxide is formed to a small extent together with sulphur dioxide when sulphur or compounds of sulphur are burned in oxygen or air. In an
oxygen tomb, in the presence of a compound which on combustion yields water vapour and oxides of nitrogen, for example ammonium nitrate, the
combustion goes completely to sulphur trioxide."
[Edited on 8-1-2014 by AJKOER]
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alexleyenda
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Wow really amazing i've never seen a such thing. Thanks AJKOER for bumping the thread so I could see this :p Have anyone managed to confirm what it
was in the end?
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woelen
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I am quite sure that the yellow material, formed in the smoke in this experiment is related to the results I recently obtained in another experiment
with thiocyanate:
http://www.sciencemadness.org/talk/viewthread.php?tid=27676
Apparently, thiocyanate has a very peculiar and not well-known chemistry. Textbooks for schools and even at university level are totally silent on
these yellow compounds, you have to look into specialist papers or some more obscure data sources to find information about this.
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AJKOER
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This reference, "A Text Book of Inorganic Chemistry" by Anil Kumar De (given previously, page 599, link: http://books.google.com/books?id=PpTi_JAx7PgC&pg=PA599&a... ) notes the existence of an addition compound between Potassium thiocyanate and
SO2, namely KCNS.SO2.
A little info at "The Journal of Physical Chemistry", Volume 7, by Samuel Colville Lind,..., pages 311 to 312, link: http://books.google.com/books?id=bCfzAAAAMAAJ&pg=PA311&a... noting that SO2 is apparently more soluble in a concentrated solution of KCNS then
water.
Another source "Advanced Inorganic Chemistry, Volume 1, page 914, link: http://books.google.com/books?id=LmiVsfw46qwC&pg=PA914&a... cites the compound 9KCNS.SO2. Also, notes the use of SO2 and HNO3 in the
manufacture of SO3.
Another 1950 article addressing the reputed addition compound HNO3.2SO3 argues that the compound is most likely an addition compound of the form: NO3+
. HS2O7- (see http://www.readcube.com/articles/10.1002/recl.19500690805 ).
[Edited on 8-1-2014 by AJKOER]
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alexleyenda
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Quote: Originally posted by woelen  | I am quite sure that the yellow material, formed in the smoke in this experiment is related to the results I recently obtained in another experiment
with thiocyanate:
http://www.sciencemadness.org/talk/viewthread.php?tid=27676
Apparently, thiocyanate has a very peculiar and not well-known chemistry. Textbooks for schools and even at university level are totally silent on
these yellow compounds, you have to look into specialist papers or some more obscure data sources to find information about this.
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That would mean that the pink smoke is probably not caused by iodine then... or that thiocyanate have similar reactions with iodine. It's a shame I
don't have such compounds or I would already be in my lab experimenting with them, this is very interesting.
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