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Author: Subject: Hydrogen Sulfide: Generation and Storage
hankdavis
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[*] posted on 29-6-2008 at 01:29
Hydrogen Sulfide: Generation and Storage


I've used H2S in a handful of reactions (namely a mischievous one with household ammonia) and anyone who has used it know generating it often involves collecting the gas from a strong acid attacking another sulfide such as FeS. The only problem with this method is that the evolving gas carries acid droplets/vapor with it, requiring a further purification step. I thought I'd share a fairly simple process that gives only H2S gas and water vapor and is easy to have on hand. This is far from complicated, but I'm covering every detail because H2S is still a poison.

Al2S3 Production


You'll need:

Powdered sulfur
Powdered aluminum
High temp ignition source (magnesium, flash powder etc)
Wooden reaction vessel (a crucible is fine, but not preferable)

Mix 1.18 grams of sulfur for every gram of aluminum you use. This mixture is perfectly stable, I usually whip up an excess for later use. I usually use a 2x4 with a dip cut out of it to hold the powder, or a better reaction vessel can be built by drilling out a section of 2x4 with a door drill bit and closing off the bottom with another piece of wood. This is because Al2S3 has a tendency to adhere to ceramic and glass, and the only way to completley remove the Al2S3 is to quench it with water (dangerous + terrible smelling).

2Al + 3S >> Al2S3 + lots of heat

Once you have a pile of powder in your container of choice, get the reaction started with a fairly high temp in the same way you'd get thermite started. A easy way to do this is by cutting a firecracker in half and leaving the flashpowder end of the fuse in the mixture. Aluminum and sulfur reacts fairly violently so stand back, and mind the SO2 fumes from the excess sulfur burning off. Once the red hot Al2S3 goo has cooled, you should have a gray "rock" of your product plus flaming wood. DO NOT put this fire out with water, again with the terrible smell. After the fire goes out the burned wood should allow you to simply peel off the sulfide and break it up into pebble sized chunks (powdering not recommended).

Storage


There are a few things to be weary of when storing your sulfide. Al2S3 is extremely moisture sensitive and must be stored in an airtight container that is acid-proof. Also, it is a good idea to keep it with a drying agent. It is stable when dry and I've been able to keep it indoors without risk of poisoning. Also, H2S molecules are relatively small, somewhat larger than water, so a stoppered bottle will leak small amounts of gas over time.

From here, generating H2S gas simply involves reacting your pebbles with water to give a fairly slow evolution of H2S to be bubbled through your solution of choice. Acid speeds this reaction up.

Al2S3 + 6H20 >> 2Al(OH)3 + 6H2S + some heat

Spent aluminum hydroxide can be reacted with HCl to give a much less violent synthesis of AlCl3, a bonus reagent!

I'm currently working on an all-in-one vessel made from pvc parts and silicone. Al2S3 goes in a large valve at the top, and when H2S is needed, one simply uses a syringe to inject water into a second valve and the gas is collected from the first. With the valves closed, the vessel doubles as storage. However, I don't yet know if H2S attacks silicone, so use caution.

I've been scolded on boards about this reagent. So I'm finishing up with handling procedure...

SAFETY


First off, H2S is very poisonous at concentrations as low as 150 ppm in the air. It will deaden your sense of smell at these levels, so don't toy around it. Luckily, H2S is detectable at a thousandth of these levels, tends to sink to the ground, and will cause intense nausea before harm truly sets in.

From my experience, using H2S on the small scale is mostly harmless, especially with an Al2S3/water generator because H2S is produced more slowly. Always use ventilation during these reactions and preferably outdoors on a dry day. If you absolutely need to use H2S indoors, bubble your excess gas through an diffuser and a scrubbing solution that traps the sulfide ion. Sodium salts are undesirable as the sulfide will slowly decompose back into H2S. Personally, I dissolve KMnO4 into dilute HCl and H2O2 until MnO2 forms. The manganese ion will trap the sulfide and the MnO2 catalyzes the formation of the less toxic sulfate ion. Finally, H2S will readily form lingering smelly sulfides on surfaces indoors such as wallpaper so indoor use can be destructive to your property.

Again, sorry for the wordiness, but I felt it necessary. Good luck!




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[*] posted on 29-6-2008 at 15:38


Another option: According to Merck thioacetamide, C2H5NS, can be made by heating Al2S3 with ammonium acetate, i.e.:

3[C2H7NO2] + Al2S3 --> 3[C2H5NS] + 2Al(OH)3

Again, from Merck, thioacetamide is a "Pleasant substitute for H2S in the lab."




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UnintentionalChaos
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[*] posted on 29-6-2008 at 16:59


I've made tiny quantities of aluminum sulfide and it really does reek even just as the reaction stops. The small samples were prepared by ignition with magnesium filings and proceeded quite energetically. The sulfur melted together with dark aluminum powder with no obvious reaction..like the original post mentions, it needs to be lit like a thermite. I did not have an immediate use for it, so I quenched it with 6% H2O2 to destroy it which initially released a small amount of H2S (quick escape of bubbles from the surface of the samples perhaps) but it quickly stopped smelling altogether (and I'm sure it was not from deadening of my sense of smell...the sample was extremely small.....maybe a single gram)


[Edited on 6-29-08 by UnintentionalChaos]




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[*] posted on 30-6-2008 at 14:56


Have a read at this (very scary) story in relation to using the stuff.

http://www.sciencemadness.org/talk/viewthread.php?tid=10491&...

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[*] posted on 30-6-2008 at 16:02


I want to add that the Al/S reaction should be protected from atmospheric oxygen if possible, since such sulfides are very easily oxidised to sulfates otherwise, losing yield.

Very good synthesis though. Much better than the sulfidogen method (heating paraffin with sulfur, giving H2S and carbon) which renders the test tube it is done in useless since the coke deposit cannot be removed.




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hankdavis
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[*] posted on 30-6-2008 at 20:52


Hah sorry guys.. seeing as how I decided to write this post after a weekend bender at 4 am, disregard what I said about the "scrubber". First off, I was referring to a failed H2S removal that I ended up trashing. Secondly, contrary to my drunken ramblings, the filtration had nothing at all to do with the Mn+2 ion. What I did at the time was tried to make a thick suspension of MnO2 by adding permanganate to slightly acidic peroxide until the reaction ate all the acid and turned to a brown jelly. Running waste H2S through a column of this made the setup look AND smell like real live feces!--so I scrapped the venture entirely. I figure that unless you're a factory, it's much easier and economic to just vent the stuff as far the hell away as possible.

Garage chemist has a point, fluffier mixes give the worst yields and kick Al2S3 dust everywhere, so always tamp it down like a thermite. As far as the surrounding atmosphere goes though, try adding a dash of excess sulfur to the mix (1.25 instead of 1.18). It will burn along the surface as the aluminum sulfide cools for a minute or so, shielding it from O2 while its most vulnerable.




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[*] posted on 1-7-2008 at 02:39


Hydroxide and hypochlorites are very effective at removing H2S in scrubbers, i would rather stick to them that MnO2, the way you describ it :).
With hydroxides you end up with a sodium (poly)sulfide solution which cna be usefull (although bad smelling). Be carefull not too use a too conc. solution or over-run it, as the sulfides will start precipitating and can clog the wash bottle's tube (happened to me); on the other hand, hypochlorite leaves a fine sulfur deposit, but fine enough to to pose a clogging hazard. Both type of scrubbers can heat up significantly if large amounts of gas are to be neutralized.




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[*] posted on 2-7-2008 at 00:37


Quote:
Originally posted by dann2
Have a read at this (very scary) story in relation to using the stuff.

http://www.sciencemadness.org/talk/viewthread.php?tid=10491&...

Dann2


Yeah no joke, all it took was a humid, still day and I was trying to quench the stuff the yard. All the sudden the smell disappeared and I got a sensation in my lungs along the lines of, "Hm, this isn't air--" I got the hell out of the area and promptly puked.

Back in the day I got so much flame on the boards for even thinking about H2S you'd think it was a PhIKAL reagent, but absolutely no help with using/making it. This is actually the reason I took the time to refine the Al2S3 method and post it. Nothing against Dann2 at all, just other people who think ignorance is a safety measure.

On a lighter note, will the hypochlorite solutions still form polysulfides? The biggest pain using this reagent even during ion analysis is warning the neighbors about the smell.




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[*] posted on 2-7-2008 at 03:45


No, hypochlorite will oxidize the sulfides. INto what i am not sure, surely various oxygenated sulfur compounds (sulfites,s ulfates, etc). There was a insoluble yellow solid forming, not sure what I could have been..



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[*] posted on 2-7-2008 at 03:53


The initial product from the reaction of hydrogen sulphide with most oxidising agents ( hypochlorite, hydrogen peroxide, sodium bisulphite, etc) is colloidal sulphur.
The sulphur may then react further eg to form thiosulphite in basic sodium sulphite solutions.
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[*] posted on 2-7-2008 at 04:18


Ok, so it was sulfur then. Thanks for poiting that out.



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[*] posted on 5-7-2008 at 12:24


Quote:
H2S is still a poison


Yes it is. And I believe it is more toxic than HCN. I think the mode of toxicity is binding to the heme iron in red blood cells.

One of the bad things about working in sulfur chemistry is that most of these materials smell similar to the gas odorants added to natural gas, etc. Their potency & that fact could bring the FD & police to your door very quickly.




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[*] posted on 5-7-2008 at 16:26


Wikipedia has a list for the toxicity of H2S:
Quote:
http://en.wikipedia.org/wiki/Hydrogen_sulfide

• 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide [1], normally described as resembling "a rotten egg".
• 10-20 ppm is the borderline concentration for eye irritation.
• 50-100 ppm leads to eye damage.
• At 150-250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger,
• 320-530 ppm leads to pulmonary edema with the possibility of death.
• 530-1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
o 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
• Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

Another way to make hydrogen sulfide is to melt iron (Fe) powder and sulphur (S) in a test tube and get FeS.
And so mix the FeS whit HCl, = H2S + FeCl
It stinks very badly :D




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[*] posted on 14-4-2012 at 17:09



H2S from Vaseline and S.



Taken from another thread here:


http://www.sciencemadness.org/talk/viewthread.php?tid=19639



Attachment: chemicals_sulfide_hydrogen_preparation_from_sulfur_prothiere1902_french.zip (608kB)
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[*] posted on 14-4-2012 at 21:55


Cooking oil works too, and the left over red oil is a wondrously stinkey commodity.
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[*] posted on 12-5-2012 at 19:58


Does anyone have any elemental selenium or tellurium to test whether this process, heating with paraffin wax, will produce H2Se or H2Te?

Please don't try this inside at home, school or work, but I'd like to know if it works. A facile source of these hydrides would be useful.
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[*] posted on 31-5-2012 at 06:22



Hello,

Scan below taken from another thread (Making Carbon Disulphide).

Also onyone messing with H2S should read this:
http://www.sciencemadness.org/talk/viewthread.php?tid=10491



carbondisulphidebrasted.jpg - 90kB
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[*] posted on 26-7-2013 at 17:42


Quote: Originally posted by Paddywhacker  
Does anyone have any elemental selenium or tellurium to test whether this process, heating with paraffin wax, will produce H2Se or H2Te?
...


At long last I can report that heating olive oil with either selenium or with tellurium produces no noticeable smell. Fusing selenium or tellurium with sulphur and then heating the product with oil produces only the smell of hydrogen sulphide. My new career as a phantom stinkbomber has died at birth.
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[*] posted on 27-7-2013 at 23:56


I once used aluminum sulfate (garden center) and Calcium, lime, rust generic toilet bowl cleaner to make H2S. We had a badger get into mom's garage and had decided to hold up in a cabinet under the workbench, using some make shift body armor and a military gas mask with SWISS NATO filters I went in with a bucket of the aluminum sulfate and poured in a 50/50 mix of toilet bowl cleaner and water. then exited the garage and locked the door, we opened the windows in the house, and then left the house. 4 hours later we came back, I used the garage door opener to open the garage door, and vent the place. we spotted the dead badger near the gargage door after it opened, along with a few mice we didn't know about.



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[*] posted on 28-7-2013 at 00:26


If sulfur is boiled with aqueous alkaline solution, polysulfides and thiosulfate form. Reaction of acid with polysulfides liberates H2S and sulfur, but the acid also reacts with the thiosulfate to release SO2 (and more sulfur). H2S and SO2 immediately react with eachother, so I do not understand how any H2S can be released, but apparently this reaction does release poisonous H2S...
Perhaps the thiosulfate react at a different rate than the polysulfides with acid? I would think it would be best to find a way to separate the two, if possible, before adding the acid.
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