Sciencemadness Discussion Board

Trying to dissolve Sulphur

CHRIS25 - 22-4-2012 at 01:09

Hallo, now I know that Sulphur is insoluble, and I read that you can dissolve sulphur with the help of carbon disulphide but this is not practical for me.

I have a Half teaspoon of Sulphur powder on a stainless steel spoon, after it has melted I add one large flake of Potassium Hydroxide and wait until that is melted, the spoon is then submerged into Hot, but not boiling, de-ionised water.

Apart from the very first attempt (which I have not been able to replicate) I get only about half strength solution of the Potassium Polysulphide, there are bits of large undissolved sulphur left over in the water.

As i said the very first time I did this it worked, and apart from the temperature variance of the water, (since I can not control it precisely) I do not know what can be improved. By the way, the amount of water is always 200ml to a half teaspoon sulphur and the same size flake of KOH is used each time.

Can you suggest a more efficient way of doing this? or a tip?

Kind Regards
Chris.

kristofvagyok - 22-4-2012 at 02:09

Long ago when I had a problem with dissolution of sulfur, then I tryed out with organic solvents, like dichloroethylene, xylene, toluene, benzene, petrol and alcohol. The most effinent was trichloroethylene, after xylene, toluene and everything else.

The problem with trichloroethylene is that it is carcinogen, toxic ect., the problem with xylene was, it has a high boiling point and it was difficult to remove and the toluene had the same problem.

Afterall I used toluene, because it was enough good for my ideas.... But all the listed solvents are good.

CHRIS25 - 22-4-2012 at 02:41

Hallo, yes thankyou, I saw already about Toluene, but did not want to complicate the process really. I have no idea how to use it or where to get it. Thankyou Kristof.

watson.fawkes - 22-4-2012 at 07:25

Quote: Originally posted by CHRIS25  
Can you suggest a more efficient way of doing this? or a tip?
What, exactly, are you trying to do? Dissolve sulfur, or make some liver of sulfur?

Tip: Buy an electronic scale. An adequate starter one can be had for ~$20 - 30. For reference, something like this one from HF.

Tip 2: Keep a lab notebook. Record quantities. Since by your own account you're getting inconsistent results, you'll do far better to start being quantitative.

CHRIS25 - 22-4-2012 at 07:40

Ah, Hallo again, well thankyou for your suggestion. Yes you are right - I need to record everything. At the moment I have two lab books, one for the equations and calculations and chemical inventory. the other for experiments. Unfortunately with this particular one I did not bother since one flake into half teaspoon is, by its, very nature, not necessary to be "gram/molecular" accurate, and yes it is liver of sulphur.

Kind regards
Chris

watson.fawkes - 22-4-2012 at 09:10

Quote: Originally posted by CHRIS25  
yes it is liver of sulphur.
The traditional methods for liver of sulfur all use fire. Perhaps the easiest is to fuse sulfur with a potassium salt. KOH both work K2CO3. All you need is a small crucible and a propane torch. For small amounts, a metal pipe cap should work fine.

Liver of sulfur has also referred to the calcium version of this, which is made with lime (quick or slaked) or chalk (the carbonate). For coloring metal, the sodium version has also been used.

CHRIS25 - 22-4-2012 at 10:50

Quote: Originally posted by watson.fawkes  
Quote: Originally posted by CHRIS25  
yes it is liver of sulphur.
Perhaps the easiest is to fuse sulfur with a potassium salt.

Hallo, Ok I will but I noticed and was a bit afraid of heating the sulphur and KOH too much since there was some spitting and assumed a mini explosion was about to happen. I had read somewhere about the volatile nature of sulphur when heated too much.

Liver of sulfur has also referred to the calcium version of this, which is made with lime (quick or slaked) or chalk (the carbonate). For coloring metal, the sodium version has also been used.


Good idea, I might well give this a try. I made my own calcium carbonate a few weaks ago by collecting white seashells from the beach, Hesitant to buy the chalk board stuff since a lot of it is now made with magnesium carbonate so I read, and had no way to tell the difference. hence the seashell outing. Thankyou for that tip though with the calcium hydroxide.

Kind regards

watson.fawkes - 22-4-2012 at 13:33

Quote: Originally posted by CHRIS25  
I will but I noticed and was a bit afraid of heating the sulphur and KOH too much since there was some spitting and assumed a mini explosion was about to happen. I had read somewhere about the volatile nature of sulphur when heated too much.
Well, then don't heat the sulfur too much. I'm serious. The melting point of sulfur is will within the range of an ordinary candy thermometer. (Don't use that thermometer afterwards for candy, of course until it's rocket candy.)

Any of these reactions are going to sputter because you're releasing SO2. If you're making enough that such spattering is a problem just use mechanical means to contains the spatter. Using a high-form crucible is the easiest, particularly if you're using iron pipe parts.

CHRIS25 - 22-4-2012 at 22:14

Thankyou, I can only get crucibles from England, or USA. Postage is a pain. I'll keep to the steel. But I am only making as required anyway, no more than 100ml solution each time. Although what did you mean by a metal pipe cap? No clue what that is.
Regards
Chris

watson.fawkes - 23-4-2012 at 06:18

Quote: Originally posted by CHRIS25  
I can only get crucibles from England, or USA. Postage is a pain.
Well, where are you then? Almost everywhere in the world has pottery or mine prospecting, both activities from which to obtain crucibles.

Here's some information on what a pipe cap is.

CHRIS25 - 23-4-2012 at 07:04

Hallo, In Ireland I found only the stainless steel and porcelain crucibles - way Over Priced and pretty much inadequate I think anyway. In USA I can get hold of high temp, (used for Gold and silver), the Graphite and fused silica for a very good price, fair and honest. I obviously live in Ireland where even the websites malfunction, everyone I know shops abroad die to the lack of transparency and unfairness in this country.

Pottery shops you say? I will have to visit one locally and see what temperature they can be heated up to, but how inertl is pottery I wonder? I will look that up. thankyou for the Pipe cap link by the way.

Kind regards

watson.fawkes - 23-4-2012 at 15:49

Quote: Originally posted by CHRIS25  
In USA I can get hold of high temp, (used for Gold and silver), the Graphite and fused silica for a very good price, fair and honest.
You are way overthinking all this. Part of it is that you aren't thinking at all quantitatively. The quantity that's relevant is temperature. So I'm assigning you some homework. (1) What's the melting point of sulfur? (that will be bit below your reaction temperature) (2) What's the firing temperature of "cone 06" clay? (that's a low fire clay used for, say, flower pots). (3) What's the softening point of borosilicate glass?

All three of these questions have answers readily available with a bit of internet searching. Once you have the number, answer the essay question: (4) Will either of these materials will work for making liver of sulfur?

Since by now you must have obtained your lab notebook (cough!), record these numbers for future use, because given your interest it seems likely you'll want to refer to them again.
Quote: Originally posted by CHRIS25  
Pottery shops you say? I will have to visit one locally and see what temperature they can be heated up to, but how inertl is pottery I wonder?
The standard little lab crucibles are nothing other than slip cast porcelain; nothing magic. If pottery weren't inert to many things, it would never have been useful.

AndersHoveland - 23-4-2012 at 15:51

Sodium sulfite, Na2SO3, solutions can also "dissolve" sulfur, but of course this is a chemical reaction producing thiosulfate. But the sulfur can be precipitated out again by acidifying the solution.

CHRIS25 - 24-4-2012 at 07:00

Hi, watson Fawkes, well thanks for the homework, last time I did homework was at my Photography diploma! Anyway to answer your questions: Sulphur melts at 115 centigrade. Firing temp of clone 06 clay was not consistent, so I averaged everything to two results: Between 1798 and 1855 F and 1828 to 2088F, and finally Borosilicate glass softens at 820 F. Well that's the test tube I presume.

But while this was helpful and interesting, and yes I mean that, my concerns come with reactivity of compounds and liquids with their holding materials, so one would not put HCL into an aluminium container for example. Also and actually more important, I have to 'pour' the melted sulphur and potassium into hot water, hence the spoon idea because the test tube lets it cool down too much as it pours. But yes, I know I will experiment more on this. By the way, I could mix the Liver of sulphur in an empty peanut butter container really. I think that the spoon, being metal, is so hot that it cools too rapidly on contact even with the hot water that it affects the melted sulphur and KOH mix. I am just going to try some different things out and see what happens.

Oh all those red lines under all my words, it happens often on other posts, you Americans really have rebelled against Our Saxon English spelling eh? Tch.

Kind regards.

CHRIS25 - 24-4-2012 at 09:48

Quote: Originally posted by AndersHoveland  
Sodium sulfite, Na2SO3, solutions can also "dissolve" sulfur, but of course this is a chemical reaction producing thiosulfate. But the sulfur can be precipitated out again by acidifying the solution.


Hi Sorry for not replying sooner, but I was doing some reading on the above. Could not find much but this is interesting. I have my Sodium Thiosulphate right? Something I wanted earlier. I dissolve Sodium metabisulphite, which automatically gives Sodium bisulphite. I add Sulphur and get Sodium Bisulphate?

Na2So3 + H2O + S (Heat up) = Na2S2o3 Is this correct please?

barley81 - 24-4-2012 at 11:34

If I wanted to make sodium thiosulfate, I would neutralize the sodium bisulfite solution with sodium hydroxide to make sodium sulfite. Then I'd boil with sulfur. The ratio is 1 mole of sodium metabisulphite to two moles of sodium hydroxide.

Unfortunately I don't think you can use cheaper sodium carbonate because sodium sulfite is more basic than sodium bicarbonate and there will be some sodium bisulfite, sulfite, and bicarbonate left in equilibrium (since pKa of carbonic acid is lower than pKa of bisulfite ion). However, I'm not sure what happens when you boil sulfur in this mixture. Perhaps CO2 gets boiled away and you do get sodium thiosulfate?

Bisulfate isn't formed. To make bisulfate you can oxidize bisulfite. For example, you could add hydrogen peroxide to a solution of sodium bisulfite (or sodium metabisulfite).

CHRIS25 - 24-4-2012 at 12:11

Thanks Barley. Plenty to get on with then.

watson.fawkes - 24-4-2012 at 12:41

Quote: Originally posted by CHRIS25  
Anyway to answer your questions: Sulphur melts at 115 centigrade. Firing temp of clone 06 clay was not consistent, so I averaged everything to two results: Between 1798 and 1855 F and 1828 to 2088F, and finally Borosilicate glass softens at 820 F. [...] my concerns come with reactivity of compounds and liquids with their holding materials
So here's a free one: both ceramics and glass are chemically compatible with your reaction. And you've now understand that you should be able to use either material for your reaction vessel. If you can find flower pots without drain holes, you should be able run this reaction in a campfire.

Now the pouring hot reaction mixture into water---what's that about? All you do is fires these two reagents together. Then you let it cool off. Only then do you hydrolyze by putting the material into solution. Then you use the solution for patina work (or whatever else).

So start with about a 2 g batch in a test tube. Calculate, say, a 25% molar excess of sulfur assuming that the potassium reacts entirely to K2S. This requires some simple stoichiometric calculations. I really doubt your original ratio (a teaspoon of sulfur to a flake of KOH) is anywhere near the right ratio. You want to start small so that you can test that what you're doing is getting you where you want to go.

Oh, and keep your lab notebook current. You did write down those temperatures, right?

CHRIS25 - 24-4-2012 at 21:59

Yes I appreciate your help in all this. Although I am aware of that plastic glass and ceramic are for the most part inert, I did not want to get caught out trying to melt some stuff in ceramic - I have a few compatibility lists gleaned from the internet, unfortunately while helpful they are geared towards their own Factory products so some of the more common materials are naturally not mentioned.

Have a nice day.

CHRIS25 - 25-4-2012 at 05:08

Hi watson fawkes: said "Now the pouring hot reaction mixture into water---what's that about? All you do is fires these two reagents together. Then you let it cool off. "

Well my suspicions were indeed confirmed. It does not work in a test tube. Once you add the KOH and melt it simply adheres to the sides and bottom of the tube, basically you can't pour it either hot or cold. So back to the Spoon and just sacrifice some un-dissolved sulphur by adding more that I need at the beginning.

watson.fawkes - 25-4-2012 at 05:21

Quote: Originally posted by CHRIS25  
It does not work in a test tube. Once you add the KOH and melt it simply adheres to the sides and bottom of the tube, basically you can't pour it either hot or cold.
Liver of sulfur is a solid. Are you expecting a liquid reaction product?

CHRIS25 - 25-4-2012 at 05:29

No, you can buy liver of sulphur as a solid or as a liquid. But all it is, as I am sure you know, is a loose combination of polysulphides, bisulphides and sulphides etc. But themain ingredient seems tyo be potassium polysulphide, which strictly speaking is a substitute, however it does the job exactly the same. Now when you mix the KOH and the S and melt they immediately dissolve into water and you have essentially your LOS. The solid that you buy you also mix with water but since their solid immediatley dissolves one can only assume that there is a 'another' ingredient which promulgates dissolution without any sulphur being precipitated.

**I probably should add that most of my mixture does dissolve, it is not a huge problem, just would be nice to quantify and keep consistent weights and measures which Ican not do accurately if some sulphur keeps precipitating.

[Edited on 25-4-2012 by CHRIS25]

watson.fawkes - 25-4-2012 at 07:11

Quote: Originally posted by CHRIS25  
**I probably should add that most of my mixture does dissolve, it is not a huge problem, just would be nice to quantify and keep consistent weights and measures which Ican not do accurately if some sulphur keeps precipitating.
Like I said, I'll bet you've got a large molar excess of sulfur, too much to react even into polysufides. Since this is a quantitative question, please tell me what masses you're using at the test tube scale, and how you came to use those values. These questions have numerical answers.

CHRIS25 - 25-4-2012 at 09:25

I can not give you numerical answers because:
1. I do not have scales that measure accurately, 1 gram is quite hard to ascertain. They are household scales, pretty accurate if you are using 10 and above grams, since I have performed many successful reactions in this weight region.
2. My sulphur is a one third slightly heaped standard teaspoon and the KOH is a reasonably rounded 1 cm diameter.

Now I know you are going to collapse in despair at this un-scientific manner. But without those chemistry scales I can do no better. Look at this way, many many experiments and discoveries were made even before the middle ages, and well, at such small minute quantities that would have been done with the eye and chalked level indicators. seriously though I saw this demonstration done on You tube by a metal worker in silver. He did not have any precipitates, but then he also did not give any precise temperatures of the water and kept using the phrase "approximately" and "about".

For the rest you can be pretty much comforted by my attention to empirical observations and analysis.

Kind regards, Chris

watson.fawkes - 25-4-2012 at 11:48

Quote: Originally posted by CHRIS25  
Now I know you are going to collapse in despair at this un-scientific manner. But without those chemistry scales I can do no better.
No, I'm going to insist that you acquire the most basic scientific equipment if you want scientific help. There are very inexpensive electronic scales available (they tend to be made in China). They're good to a tenth of a gram or so. One of those would do you fine for test-tube scale experiments. So buy one.

In the US you can get one easily for less than $20. I just checked eBay for Ireland, and even with "items only in Ireland" turned on, I found a couple dozen quickly. Plenty were less than 15 euros after shipping. I'm sure eBay isn't the only source for these. Useful search terms include "jewelry scale" and "digital scale".

While you are waiting for your scale to arrive, here's more homework: do the stoichiometric calculations. Pick an equation to do the estimate with; I'd suggest one with K2S as a product. (Hint: Wikipedia) Then figure out what mass ratio you're targeting.

CHRIS25 - 25-4-2012 at 22:12

Pick an equation to do the estimate with; I'd suggest one with K2S as a product. (Hint: Wikipedia) Then figure out what mass ratio you're targeting.

? ? ? ? ?

I am happy to learn and happy to be challenged but I am not a chemist with a knowledge of all the lingo. I really do not even understand your question. Especially when you say "pick an equation" Like E=MC2 I mean: exactly what equation?

watson.fawkes - 25-4-2012 at 23:49

Quote: Originally posted by CHRIS25  
I am happy to learn and happy to be challenged but I am not a chemist with a knowledge of all the lingo. I really do not even understand your question.
A reaction equation; reagents on the left; products on the right; an arrow between them. A balanced reaction has the same number of atoms of each element on the left and right sides. (Admittedly, the term "equation" is perhaps a little loose here.) Go read the Wikipedia page on stoichiometry for a brief introduction; the intro and definition sections should suffice.

You're reacting KOH and S. Those are your reagents. Assume K2S is one of your products. This is an idealization, but it will get you started. The oxygen and hydrogen have to go somewhere. They react with the sulfur, forming SO2 and H2S; both of these are gases, so they escape. (That's your bubbling and spattering.) With this information, you can write down a reaction (put an arrow in) and balance it (put the right numbers on it).

You're worried about consistency, and that means (1) weighing your reagents, and (2) doing some stoichiometry. There's no shortcut; you have to do both. This is also secondary school chemistry, so with a modest effort you'll understand this.

CHRIS25 - 26-4-2012 at 00:45

Ok, yes the term "equation" through me a bit. But here is how I already work things out:
S+KOH=K2S+SO2+H2S
THEREFORE: (using a childish way but it works for me)

1 S 3
1 K 2
1 O 2
1 H 2

So to equalize both sides I have to:

Therefore to balance would be: 3S+2KOH=K2S+SO2+H2S ??

watson.fawkes - 26-4-2012 at 05:14

Quote: Originally posted by CHRIS25  
(using a childish way but it works for me) [...] 3S+2KOH=K2S+SO2+H2S
Yes. Although it's usually written with an arrow and with subscripts (to make subscripts, use the button labelled XY in the editor): 3 S + 2 KOH --> K2S + SO2 + H2S. As for the "childish way", the general way requires linear algebra. Most equations can be worked out quickly, though.

The next step is to compute the molar mass of each of your reagents. You do this by adding up all the atomic weight of each of the constituent elements, weighted by their ratios in the molecule. The atomic weight is the mass, in grams, of one mole of the atom. One mole is an Avogadro's number of atoms. The resulting sum is the mass of one mole of molecule in question. You can find the atomic weight in pretty much any periodic table.

CHRIS25 - 26-4-2012 at 12:53

So 96gr sulphur and 56gr KOH will give 110gr potassium sulphide 64gr sulphur dioxide gas and 34gr hydrogen sulphide gas. So now we need to factor water into all this. H = 1 and O = 16 therefore H2O = 18 since H is 2 times the 1.

Therefore: 50mls water = 900grams (50 x 18) I notice that 1ml of water usually equates to 1 gram on weighing. Which theoreticaly gives a weak solution in this instance of dissolved potassium sulphide and quite acidic due to the hydrogen sulphide in the water. Or am I now going ahead of myself here?

watson.fawkes - 26-4-2012 at 13:46

Quote: Originally posted by CHRIS25  
So 96gr sulphur and 56gr KOH will give 110gr potassium sulphide 64gr sulphur dioxide gas and 34gr hydrogen sulphide gas.
That's all correct.
Quote: Originally posted by CHRIS25  

So now we need to factor water into all this. H = 1 and O = 16 therefore H2O = 18 since H is 2 times the 1.

Therefore: 50mls water = 900grams (50 x 18) I notice that 1ml of water usually equates to 1 gram on weighing.
And nope. You've confused density (mass per unit volume) with molecular weight (mass per mole). The density of water is indeed about 1 g / ml. 50 ml of water, though, has (50/18) = 2.78 mmol (milli-moles, one thousandth of a mole) of water in it.

CHRIS25 - 27-4-2012 at 10:56

Sorry watsonfawkes, forgot to say thankyou for your helpful advice, and yes I was silly about that water calculation should have known better.

Kind Regards
Chris

watson.fawkes - 29-4-2012 at 08:27

@CHRIS25: (1) Have you ordered a scale?

(2) Even lacking a scale, you can get a rough idea of the masses of small volumes by weighing a larger amount measured by volume and dividing down. By water volume, a tablespoon is 1/2 oz and a teaspoon is 1/6 oz. So measure out, say, 1/2 cup (4 oz. water) of your reagents (KOH and S), weigh them, divide by 24, and you've got the mass of a teaspoon of reagent. You won't have the highest accuracy, but it's certainly enough for liver of sulfur.

Now compare to the ideal reagent masses for K2S. How does what you were doing before compare to this calculation?

CHRIS25 - 29-4-2012 at 10:27

Hi Watson.Fawkes, yes ordered the scales a couple of days ago. Cheap, well very cheap compared to the 500 and 1500 euro scales that I've seen. Anyway, they claim 0.1 to 500 grams. so being cheap at 10 euro I hope they measure up (excuse the pun). No calibration ability but obviously I shall take some known weights and average out their reliability. In any case they certainly will suffice for now. I am purposefully awaiting the scales before making any solutions so that I can run a series of consistent tests and take it from there. I will let you know the results etc, I shall keep to this conversation rather than starting a new topic.

Thankyou.

watson.fawkes - 16-5-2012 at 06:08

Reply from another thread:
Quote: Originally posted by CHRIS25  
By the way, as an offshoot, while you are here, I said I would keep you up to date with that Potassium Polysulphide mixture (LOS) I measured out 2.4 grams of sulphur and 1.6 of KOH, heated until melted and places in 100ml hot water. I did this three times and reduced the Sulphur to 1.5 and KOH to 0.4 grams twice, I got a good solution and was able to perfect the colours for a couple of projects, but on the chemistry side, there was always 0.3 to 0.5 grams of undissolved sulphur in the solution, the same range of amount no matter what I did. At least I can always factor this into my equations when I make a solution every week. But Nope, I can never get it to fully dissolve. Kind Regards.
You computed before that 96 g S and 56 g KOH are the stoichiometric ratios for a single designated reaction; that's approximately a 1.7:1 ratio. The stoichiometry for the K2S reaction is only one of the many reactions that are possible here. If I read your report right, you're getting a reaction with a 1.1 (1.5 - 0.4) : 0.4 = 2.75:1 ratio, which means you are getting a polysulfide product, not just the bisulfide. That's fine; liver of sulfur is traditionally a polysulfide.

Since you're in the right ballpark on mass ratios, I would have to guess that the reaction isn't going to completion, that it's ending too soon. I don't know what the reaction time should be, or what it used to be. If you're using a crucible with a lid, you might try just leaving on the heat for longer and see if you get a more complete reaction. You also might drop the sulfur mass a bit.

The end result, though, is that if you're getting a consistent product that's adequate for your use, everything else is optimization.

CHRIS25 - 16-5-2012 at 06:55

The reaction is instantaneous, once you dip the KOH and S into the H2O you have your Polysulphide. But just maybe the mass of the sulphur is too much. Well, as you say, I like optimization::) and so for purely learning purposes I will try and perfect this. Have a nice day.

watson.fawkes - 16-5-2012 at 08:06

Quote: Originally posted by CHRIS25  
The reaction is instantaneous, once you dip the KOH and S into the H2O you have your Polysulphide.
There are two reactions here. The first is the fusion reaction of KOH and S. This happens at heat in a crucible. The second is a hydrolysis, where you douse the crucible product in water.

I had been talking about the first step, not the second. But now I have to ask. Are you just adding KOH and S directly to the water, without prior fusion?

CHRIS25 - 16-5-2012 at 09:02

No No... I melt the sulphur gently then when it is 90% melted I add the KOH flakes and wait until all is melted. If I heat to long the fused chemicals begin to spatter a bit, so I have learned to add the fused KOH and S to the warm water just before it spatters and turns an even deeper brown.

[Edited on 16-5-2012 by CHRIS25]

ScienceSquirrel - 16-5-2012 at 09:09

Quote: Originally posted by CHRIS25  
No No... I melt the sulphur gently then when it is 90% melted I add the KOH flakes and wait until all is melted. If I heat to long the fused chemicals begin to spatter a bit, so I have learned to add the fused KOH and S to the warm water just before it spatters and turns an even deeper brown.

[Edited on 16-5-2012 by CHRIS25]


Are you allowing for the fact that potassium hydroxide pellets are typically 75 - 85% potassium hydroxide, the balance is water that cannot be driven off.

CHRIS25 - 16-5-2012 at 09:43

Well I have KOH Flakes that clearly state 99%+. And also I notice that if I leave a flake out for longer than two minutes it begins to absorb moisture, so I am assuming that these flakes are truly at their max dryness.

[Edited on 16-5-2012 by CHRIS25]

watson.fawkes - 16-5-2012 at 11:02

Quote: Originally posted by CHRIS25  
If I heat to long the fused chemicals begin to spatter a bit, so I have learned to add the fused KOH and S to the warm water just before it spatters and turns an even deeper brown.
Ah. If the reaction goes to completion, it's going to bubble and spatter, because you're evolving gases in the reaction: SO2, H2S, and water (from the KOH, as ScienceSquirrel points out). This spattering, though annoying, is to be expected. I don't know what kind of vessel you're using, but you can either use a taller vessel or use a lid. After all the reaction gases have evolved it will stop spattering, because the resulting polysulfide isn't volatile at the fusion temperature. After the vessel cools, you can rinse it out with part of the water of your product solution.

The darker brown isn't really a problem. All it means is that your polysulfides are getting more poly, that is, polymerize more sulfur into the product.

My apologies for forgetting about the water content when measuring out KOH. It does indeed affect the practical ratios you need.

CHRIS25 - 16-5-2012 at 12:39

Ok I will try things again to beyond the spattering. But some weeks ago I did this in a test tube and allowed the spattering to beyond this point - but it would not pour, it just remained a goo, a mess of treacle stuck to the sides of the glass.

Actually I forgot to say something which I think is quite important. Sulphur when mixed with water floats, so it is less dense. But every time I have sulphur left over it lies on the bottom of the water? Does this say anything important? That last bit was terrible grammar - ..."it sinks"...:)

[Edited on 16-5-2012 by CHRIS25]

[Edited on 16-5-2012 by CHRIS25]

watson.fawkes - 16-5-2012 at 16:04

Quote: Originally posted by CHRIS25  
Ok I will try things again to beyond the spattering. But some weeks ago I did this in a test tube and allowed the spattering to beyond this point - but it would not pour, it just remained a goo, a mess of treacle stuck to the sides of the glass.

Actually I forgot to say something which I think is quite important. Sulphur when mixed with water floats, so it is less dense. But every time I have sulphur left over it lies on the bottom of the water? Does this say anything important? That last bit was terrible grammar - ..."it sinks"...:)
Liver of sulfur is a solid. The solution you've seen is the hydrolyzed form of it after adding water. The substance itself is the solid. It has a long shelf life, unlike the solution.

The goo you saw, I would imagine, is what you get when you have a lot of excess sulfur. With the right amount of sulfur, you should get fusion to a dry mass.

Also, you should know that sulfur polymerizes above its melting point and turns to plastic. At that point it's only a liquid strictly speaking. Above another temperature it re-liquifies. In other words, don't overheat it.

As for the density issue, ordinary sulfur with no entrained air is denser than water, but particulate sulfur might float because it's got tiny air bubbles trapped or attached to the particles. Regular α-S8 (the ordinary allotrope) has a density of 2.07 g cm-3, so it would sink in water.

CHRIS25 - 18-5-2012 at 04:30

Hallo,

Ok after many repetitions of fusing and melting the S and KOH using the following parameters: 1.0g S and 0.4 g KOH; 1.5g S and 0.4g KOH - I did 6 experiments. three with each computation.

Three Methods tried: a) Heated gently in Stainless steel spoon, waited until sulphur melted and remained free flowing then added KOH and waited until completely fused.
b) Heated gently until sulphur melted and slightly overheated longer than above, added KOH and let that melt.
c) Heated gently until sulphur melted and overheated even longer than (b) added KOH and continued to heat even after KOH had dissolved and then fused to a solid Red/brown mass.

Each sample added to boiling water (160mils).
Results: All three left roughly the same amount of undissolved sulphur in water. The only difference was with (C) where because of the total fusion of the S and KOH to a point where it became70% solidified, there was very little dissolving in the water and yet there was still that undissolved sulphur equalling the same amounts as (a) and (b).

As I said before this was just done as an experiment to see what was happening and whether or not different temperatures and different ratios of S to KOH would make any difference to the ability of Sulphur to dissolve completely in the water. It did not. It does not make much of a difference to my actual practical application but the exercise was worth it.

dissolving sulfur

tchem - 20-1-2014 at 11:09

I need to dissolve sulfur to shoot it into myGS/MS, it will dissolve in the toluene as long as it is heated but once it starts cooling I'm back to square one. I have tried DCM, hexane, methanol, IPA, toluene and a few others. Will the xylene dissolve it and keep it dissolved? Or is there something else I can try?

Metacelsus - 20-1-2014 at 14:11

Carbon disulfide?