Sciencemadness Discussion Board

Sulfur purity

nelsonB - 4-4-2016 at 08:25

so there these bag of sulfur sold in a hardware store/hunting store
apparantly its used in hunting, not sure for what purpose in hunting.
well i want to know what i could do to determine the purity of the sulfur and if there any other constituent of it, and if its impure what could do to purify it.
i was thinking recrystalisation with xylene but i tought its give it a nice look but i am not sure if its really help purifying it.

UC235 - 4-4-2016 at 08:32

If they're the same as garden sulfur, which I suspect, they will be pellets of sulfur and dirt/grit held together with some sort of binder. crush them and wash with water repeatedly, extract the result with hot toluene/xylenes and be prepared to filter it off from pasty gray grunge. The stainless steel screen from a disc-type oil filter works well for this.

Frankly it's not worth the effort/cost when you can buy high purity sulfur online.

nelsonB - 4-4-2016 at 08:59

well at the first glance its a fine pale yellow powder
i may but some soon might take a picture
i think its more pure than the sulfur used in gardening.

136SHB.png - 3.4MB

apparantly its sulfur and mineral.
so i guess the mineral are highly soluble but its give us no idea about how much sulfur is in these bag.

[Edited on 4-4-2016 by nelsonB]

fluorescence - 4-4-2016 at 10:06

Do you have medical sulfur where you live ? Here in Germany you can buy it
in every pharmacy as pure element since it's used for I dunno what purporse.
Once bought some and never really used it. But I saw it in many shops as well
like esoteric shops and so on. That should be quite pure I guess if they use
it for any medical purpose.

One way to determine the purity is actually something many students often forget about
when they have to do an analysis of inorganic salts, to check it under a microscope.
There you can see how many different things you have in there based on crystal structure,
transparency, color and sizes. Also if there are minerals in there adding it to some water
or acid might also help to get some impurities into solution.

If you see more than one compound under the microscope I suggest you try out some stuff,
not solvents for the sulfur but rather for anything besides sulfur. And then check again with the
cleaned product. And if you find a method that reduces the amount of impurities you can just
upscale it.

For the Xylene method...well if you asked me...I once read about a way to precipiate something highly soluble using
silver salts in a reaction. The idea is good but doing it is hard since the solution had many chemicals in there to assure the mixture was stable. Considering that Silver will precipitate out with like 90% of the stuff you add to it and all the additives it will be quite hard to get the silver even close to there. If something cant be prec. using any other method but silver then silver which is just the opposite wont stay in solution for that long. Same applies for your stuff. Sulfur has always been something that was insoluble. Often used for seperation experiments and demonstrations we think about sulfur of something that doesnt dissolve in most stuff meaning that you treat it quite badly and it will stay in its elemental form. And I guess that would be the key to clean it. Get rid of anything but the sulfur not the sulfur itself ;)

[Edited on 4-4-2016 by fluorescence]

Daffodile - 4-4-2016 at 17:23

Its usually sold as a miticide. It can be purified by recryst or precipitated from Polysulfide solution.

hyfalcon - 4-4-2016 at 18:22

Wouldn't sublimation also be a purification route?

Volanschemia - 4-4-2016 at 19:29

I must be really lucky, because I have a garden supply store near me that sells Sulphur that dissolved without a trace in Xylenes. Doesn't seem to be any impurities at all. :D

feacetech - 4-4-2016 at 20:34

Sulphur is very easy to check for relative purity

Carbon in Sulphur

Scope and Application
Although this method is valuable as a rapid routine check it is not reliable when applied to high carbon sulphurs, where reproducibility is not better than 10-20 %.

Summary of Method
Sulphur is burned off and the residue is weighed.

For high carbon sulphurs the residue is 'carsul' coke which contains c.50 % sulphur and thus results are invariably high, although there are compensation errors such as premature volatisation of hydrocarbons, selective burning of carbon at the air-sulphur interface etc.

Hot plate.
Vacuum desiccator for cooling hot samples.
Thermostatically controlled oven at 100 oC +/- 1 oC.
Muffle furnace

Heat a porcelain crucible overnight at 100 oC +/- 1 oC, desiccate and weigh to the nearest 0.1 mg.

Weigh to the nearest 0.1 mg about 25 g of sulphur into a pre-weighed crucible.

Place crucible and sulphur on a hotplate in a fume cupboard with the heat on high and ignite sulphur.

Turn heat down enough to keep the sulphur burning. If the residue on the crucible starts to glow, remove from heat until glowing stops, then continue but at a lower heat.

When all traces of sulphur have burned off, cool crucible in a desiccator and weigh.

Mass of carbon = mass crucible after ignition - mass crucible after 800 oC heating (after ash test)

Ash in Sulphur

Heat a porcelain crucible overnight at 100oC + 1oC, desiccate and weigh to the nearest 0.1 mg.

Weigh to the nearest 0.1 mg about 25 g of sulphur into the pre-weighed crucible.

Determine the carbon in Sulphur

Place the weighed crucible into the muffle furnace and heat to 800oC for thirty minutes.

Allow the crucible to cool slightly, but not below 100oC, then place in a vacuum desiccator. Cool to room temperature and weigh.

Mass of Ash = mass crucible after 800oC - original mass crucible.

Moisture correction can be applied 100oC for 1 hour to determine Sulphur moisture.

Sulphur can be up to 2% moisture or more for safety reasons due to bulk handling

Bert - 4-4-2016 at 21:18

Quote: Originally posted by hyfalcon  
Wouldn't sublimation also be a purification route?

Only if sulfuric/sulfurous acids in your Sulfur are not an issue... Don't go this route if pyrotechnic use with chlorate is intended.

Dr.Bob - 5-4-2016 at 04:45

More so, don't mix sulfur with any chlorate unless you are well trained and have an up to date will. While there are a few useful mixtures that might require this, they are mostly advanced and unusual. That is a mix that is very likely to cause unintended fires and explosions, to the detriment of your limbs and body. While I am all in favor of a good pyrotecnic, having them go off while mixing them is poor form.

solo - 5-4-2016 at 14:33

....previous thread on the subject.....solo

[Edited on 5-4-2016 by solo]

Metacelsus - 5-4-2016 at 14:53

It's possible to sublime sulfur under inert gas to prevent oxidation and acid formation:

macckone - 5-4-2016 at 18:51

Sublime then rinse repeatedly with distilled water to remove acid.
sulfur to be mixed with chlorate should be neutralized with an appropriate base.
or just don't use sulfur with chlorate which is much better practice.

nelsonB - 7-4-2016 at 22:32

047332-c.jpg - 97kB

Apparently this one is pure sulfur to be added to saline for animal.
so there should be no salt in it.
maybe this one should be pure.
or enought pure for most purpose
also the color look like more solid than the first i send.

[Edited on 8-4-2016 by nelsonB]

[Edited on 8-4-2016 by nelsonB]

Mabus - 8-4-2016 at 08:33

I recrystallized sulfur with xylene and it worked pretty good.
Unfortunately the leftover sulfur from the xylene turned brown on the second recrystallization and had a bad smell. Later I learned that the xylene I used had traces of n-butanol and I think that's what caused it. So make sure to read the label before using any solvent.