Derek McOlund
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H2S preparation
Hi, I need some hydrogen sulfide to make manganese sulfide. What's the best (cheapest and easiest) approach without using any strong acid?
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Boffis
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The tradition method is to heat sulphur and paraffin wax. Fused iron sulphide reacts even with very dilute HCl and H2SO4.
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ave369
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Be careful with this gas. It's a killer. If you suddenly stop smelling it, turn everything off and run for fresh air!
Smells like ammonia....
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Sulaiman
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as a teenager I made a lot of iron sulphide using iron and sulfur powders, as learned in school,
e.g. https://www.youtube.com/watch?v=NxAeQneITNA
but this sounds better
https://www.youtube.com/watch?v=g7v9NYQIQ8k
I have watched videos of H2S dangers in the petrochemical industry - super scary
but based on my earlier amateur stupidity
- the intolerability of the smell will keep you safe from the gas
but not necessarily from irate neighbours 
[Edited on 10-12-2016 by Sulaiman]
[Edited on 10-12-2016 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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DDTea
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Quote: Originally posted by Sulaiman  |
I have watched videos of H2S dangers in the petrochemical industry - super scary
but based on my earlier amateur stupidity
- the intolerability of the smell will keep you safe from the gas
but not necessarily from irate neighbours
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H2S does have a potent, characteristic odor at low concentrations. Unfortunately, at high (dangerous) concentrations, it is odorless. I suspect the
receptors responsible for olfaction become saturated and inhibited--they are metal based, after all: http://pubs.acs.org/doi/abs/10.1021/jacs.6b06983 .
Hemoglobin is also metal based and may be inhibited by H2S. Be safe when working with this stuff.
Make sure to use appropriate ventilation / scrubbers for your setup to capture fugitive emissions.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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TheMrbunGee
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You can also react sulfur with aluminum powder, then react aluminum sulfide with water to have H2S!
[Edited on 11-12-2016 by TheMrbunGee]
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AJKOER
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Comments on Al2S3 preparation from Wikipedia (https://en.m.wikipedia.org/wiki/Aluminium_sulfide ), to quote:
"Aluminium sulfide is readily prepared by ignition of the elements[6]
2 Al + 3 S → Al2S3
This reaction is extremely exothermic and it is not necessary or desirable to heat the whole mass of the sulfur-aluminium mixture; (except possibly
for very small amounts of reactants). The product will be created in a fused form; it reaches a temperature greater than 1100 °C and may melt its way
through steel. "
Note, I suspect more accurately, the burning of sulfur and Al likely forms polysulfides also and with water, polysulfides of hydrogen (for example,
H2S2).
A less 'hot' approach is electrochemical based on the so called Aluminum Sulfur battery (see, for example, "Aluminum and sulfur electrochemical
batteries and cells", US patent 5,413,881, link: http://www.google.com/patents/US5413881 and a more academic reference, https://www.google.com/url?sa=t&source=web&rct=j&... ). The cell reaction is given generally as:
2 Al + 3S + 3OH- + 3H2O → 2Al(OH)3 + 3HS- ; Ecell =1.8 V
where I would employ an excess of Aluminum. Now, if one adds an acid source to the product, expect H2S. However, my last reference mentions a
polysulfides presence as well, so again not a pure product.
[Edited on 11-12-2016 by AJKOER]
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unionised
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It's a matter of definition of "acid" but adding water to Al2S3 will make H2S.
If you react an excess of aluminium with sulphur you won't get polysulphides.
The lightest hydrogen polysulphide boils at about 70C and is thus likely to be left behind in the reaction mixture.
Even when you try to make the hydrogen polysulphides the yield is poor, so I doubt you will get much of it by accident.
The big problem with using Al as the reducing agent is that the Al/S reaction is very violent.
Iron works fine; why make things difficult?
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Derek McOlund
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Well I'm working on a projekt to convert MnSO4 into H2SO4 and MnS, that's possible to do with H2S: H2S + MnSO4 --> MnS + H2SO4.
In this project I'm trying to not use as easy available chemicals as possibly, and HCl isn't very easy to buy.
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Metacelsus
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I've done this; it works quite well. Keep in mind that the reaction is highly exothermic, so don't run it in anything you care about.
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nezza
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You will not be able to make H2SO4 from MnSO4 and H2S in an aqueous environment. MnS has a highish solubility product and is soluble in dilute H2SO4
so the equilibrium H2S+MnSO4 <> MnS +H2SO4 lies well to the left. Adding MnS to aqueous H2SO4 gives H2S, rather that the reaction working the
other way.
If you're not part of the solution, you're part of the precipitate.
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ave369
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One could try this with CuSO4. CuS has very, very low solubility, if I remember correctly.
Smells like ammonia....
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Amos
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| Quote: Originally posted by Derek McOlund | Well I'm working on a projekt to convert MnSO4 into H2SO4 and MnS, that's possible to do with H2S: H2S + MnSO4 --> MnS + H2SO4.
In this project I'm trying to not use as easy available chemicals as possibly, and HCl isn't very easy to buy. |
This isn't going to work at all, unfortunately. Just as we've been describing the reactions of various metal sulfides reacting with even weak acids
like water below, manganese sulfide produced would only immediately react with sulfuric acid formed as a co-product and regenerate hydrogen sulfide.
This is the same reason you couldn't add carbon dioxide to a solution of manganese sulfate to precipitate the carbonate; a weaker acid like carbonic
acid or hydrogen sulfide will not displace a stronger acid from a salt, at least as a general rule.
[Edited on 12-12-2016 by Amos]
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WGTR
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MnS Preparation
 
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