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CHRIS25
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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?
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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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.
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CHRIS25
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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 ??
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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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.
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CHRIS25
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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?
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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| 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.
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CHRIS25
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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
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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@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?
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CHRIS25
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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.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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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.
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CHRIS25
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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.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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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?
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CHRIS25
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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]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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ScienceSquirrel
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| 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.
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CHRIS25
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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]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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| 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.
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CHRIS25
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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]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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| 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.
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CHRIS25
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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.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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tchem
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dissolving sulfur
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?
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Metacelsus
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Carbon disulfide?
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