Saerynide
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Iron Sulphate makes H2S??
I had some iron sulphate solution (Im assuming its iron (III) cause its dark tan brown) which I heated on a gas stove in a beaker. After all the
water boiled off, there was a tan colored block of crystals. I heated it til the crystals lost thier water.
They looked like this
Then, I mixed some of those crystals with water, and the resulting solution is milky white. I swirled it around and it fizzled, giving off H2S  The white solution turns grey, then brown and transparent over time.
The white and grey solutions look like this.
The brown solution looks like this The particles of rust in there came from a knife I accidently left in the solution over night.
Mixing anhydrous CuSO4 with water does not give any white/grey milky solutions, nor does it produce H2S, so, Im assuming that this is not supposed to
happen with iron?? If so, what couldve happened?
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BromicAcid
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That's quite the quizabuck for me to ponder. Ferric Sulfate shouldn't evolve any gas when it dissolves in water, neither should ferrous
sulfate, unless maybe when the crystals were forming gas was trapped within. How did you confirm that it was hydrogen sulfide, smell? Ferric sulfate
is yellow crystals or grayish-white powder, the second matching your picture somewhat. You said you heated over a gas burner, ferric sulfate
supposedly decomposes at 480 C, most beakers would shy away from this temp for prolonged periods but maybe there was some decomposition.
Was there anything else in the solution that you know of? Usually ferrous sulfide is used to generate hydrogen sulfide by dropping in acid, it barely
releases a bubble when dropped in normal water, was it just normal water you dropped your product into?
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Saerynide
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Yep, it gave off the putrid rotten egg smell, unless theres another gas that resembles H2S, then I wouldnt know...
Youre right, the beaker didnt make. As the ferric sulphate was going anhydrous, I heard the popping sound of breaking glass. Good thing pyrex
doesnt explode so easily  [and shit, I needed to return this beaker to my
teacher too...]
Edit: The bottom of it cracked, good thing the bottom didnt fall off
There could be some magnesium sulphate in there as well, but Im positive the only anion in there is sulphate.
I dropped some of the product into tap water (maybe I shouldve used distilled water...)
[Edited on 5-2-2004 by Saerynide]
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vulture
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Maybe you had Iron(II)sulfate which reduced some sulfurous acid or sulfuric acid to H2S?
FYI, this is a very wild guess.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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guaguanco
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What's the purity of your presumed FeSO4?
As another poster mentioned, you could easily have some impurities in there, including FeS.
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Organikum
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impurities
I back this up.
When making zincchloride from ZnO I have the "rotten egg" smell all time and so I say: Impurities.
If it would make really H2S you would smell it just for a second or two directly after starting the reaction - then you would have left the place or
be dead.
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guaguanco
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Well, I've smelled H2S lots of times, and I'm not dead. It's detectable in very low concentrations...
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Organikum
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thats the trick
As long as you can smell it, it is in a very low concentration, traces so to say.
Higher concentrations disable your ability to smell H2S in seconds - and kill you then.
When working with H2S:
As soon as you dont smell the rotten eggs anymore - run for your life.
No joke.
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Saerynide
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| Quote: | | Originally posted by OrganikumIf it would make really H2S you would smell it just for a second or two directly after starting the reaction -
then you would have left the place or be dead. |
I did leave. God Im dead terrified of that stuff. You guys called me crazy when I ran for my life when my electrolytic cell was spewing H2S 
| Quote: | Originally posted by vulture
Maybe you had Iron(II)sulfate which reduced some sulfurous acid or sulfuric acid to H2S?
FYI, this is a very wild guess. |
Sounds interesting. Could you expand on that a bit more? 
[Edited on 6-2-2004 by Saerynide]
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unionised
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H2S has a very strong smell so you wouldn't need to make a lot of it before you could smell it.
Dust from the air tends to contain a fair amount or organic stuff which would give carbon when heated.
I know that hot carbon will reduce calcium sulphate to the sulphide so I guess this would happen with ferric sulphate, the complication would be that
you would have to reduce the iron too.
That gives a plausible source of FeS.
The remaining ferric sulphate would be quite acid when you added the water and would displace H2S from the FeS.
I'm sure the textbooks say that ferric salts oxidise H2S, but I guess that reaction is slow enough that some escapes and that is what you
noticed.
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Saerynide
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Hmm thats probably the case, since H2S was only given off for a second or less.
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chloric1
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sulfate reduction
I am going along with vulture on this one. At elevated temperatures, sulfate is easy to reduce. About 8 years ago, I spilled 90 + % sulfuric acid on
steel that was heated just below dull red(300- 400C?). Anyways, I violent eruption of moist SO2 evolved and left a light crust of the ferric sulfate
on the steel. Now, since you had hot ferrous ion I could easily see it going another step to hydrogen sulfide. Maybe you have elemental sulfur as
well. Reproduce the experiement when convenient and dissolve residue in 30% NaOH and test for sulfide and tell us what you see.
Fellow molecular manipulator
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Saerynide
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Hmm, I'll have to make some NaOH. Maybe I'll set up a cell tomorow morning
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