Sciencemadness Discussion Board - Help! Potentially dangerous acid formed!

Help! Potentially dangerous acid formed!

happycamper723 - 25-4-2012 at 13:12

Doing a bit of research I have found that if you burn sulfur and then tube the resulting SO2 into H202 you can make crude and diluted sulfuric acid. This was fantastic because all of the ingredients were cheap, readily available, and the dilutedness of the sulfuric acid is better than the rather dangerous 98% kind. So, I set up my lab equipment and proceeded with the experiment.

HOWEVER, something went horribly awry. I had left water droplets in the jar in which I kept the sulfur. When I turned on the heat and stoppered off the jar (to tube the SO2 into the H2O2) the water turned into steam. Figuring it could only reduce the acidity of the sulfuric acid, I continued.

It was going well until the condensed droplets began mixing with the melted sulfur. They made strange sizzling noises and formed something brownish yellow, which left behind a black substance.

Terrified, and believing I had made hydrosulfurous acid, I turned of the heat and stoppered off the jar totally (no tube).

What have I made?! How do I deal with it?

Is it hydrosulfurous acid????

GreenD - 25-4-2012 at 13:24

whats it taste like?

Wizzard - 25-4-2012 at 13:30

Oxygenate the questionable material- H2S will oxidize harmlessly.

rannyfash - 25-4-2012 at 13:49

do you mean hydrosulphuric acid? or sulphurous acid?, since your sulphur burned black im assuming its contaminated, im not too fond with unknown organosulphur compounds and their related toxicitys, if it was me i would ignite the suspected H2S gas, its heavier than air so should be safe taking the stopper off in a well ventilated but air current shielded area, if there is no combustion then just rinse out the sulphurous acid, i reckon what you have is sulphurous acid which is not that toxic relative to h2SO4,

chemrox - 25-4-2012 at 14:01

make a fume hood

rannyfash - 25-4-2012 at 14:18

Quote: Originally posted by chemrox

make a fume hood

if you dont have one its a huge addition that removes alot of dangers

happycamper723 - 25-4-2012 at 15:29

Quote: Originally posted by Wizzard

Oxygenate the questionable material- H2S will oxidize harmlessly.

What will it oxidize into?

So S(l) + H₂0 -----> H₂S + 0₂?

It seems like the oxidization would be fairly instant.

The jar that had been stoppered off was only about 25% full of S02 and water droplets...there was plenty of oxygen...

nyll - 25-4-2012 at 20:06

Quote: Originally posted by chemrox

make a fume hood

make a gas chamber

woelen - 25-4-2012 at 22:45

@happycamper723: Don't be so afraid. Just go outside, screw the cap from the jar, step back and allow its gaseous contents to go into the air. You may smell some of it, but even then there is no need to be afraid.

This is a typical case of chemophobia, due to ill-informedness and lack of knowledge. If you are so afraid for what you make and do, then I think it is better to choose other activities. Reading up more before doing experiments also may help. Using sufficiently pure chemicals (general lab grade is good enough, no need to buy analytic reagent grade) also is important if you want to learn something from your experiments, otherwise you get all kinds of unpredicatable and hard to understand side-effects.

In general, with the standard materials you can get around the house and in agriculture shops and hardware stores you hardly can make extremely toxic compounds which can kill you, provided you work with small amounts. Also working outside reduces the risk to nearly 0.

You most likely have a complex mix of oxoacids of sulphur, contaminated with organics (the black stuff cannot come from the sulphur). A stinky and unpleasant mix, but not instant death in a bottle.

rannyfash - 25-4-2012 at 23:16

Quote: Originally posted by happycamper723

Quote: Originally posted by Wizzard

Oxygenate the questionable material- H2S will oxidize harmlessly.

why dont you calculate gibbs free energy on that equation, that will tell you if that reaction is feasible at the temperature it was heated at

barley81 - 26-4-2012 at 02:53

Oxygen pretty readily oxidizes hydrogen sulfide. That's why hydrogen sulfide burns. If there isn't enough oxygen for the flame, sulfur is deposited. Therefore you can write your name on a piece of tile with burning hydrogen sulfide. So, since the reverse reaction is spontaneous (though requiring activation energy), delta G for the forward reaction is negative. The forward reaction is not spontaneous.

Anyway, it's the reverse reaction that happens when you oxygenate hydrogen sulfide. Just add some hydrogen peroxide:
H2S + H2O2 -> S + 2H2O.

[Edited on 26-4-2012 by barley81]

[Edited on 26-4-2012 by barley81]

happycamper723 - 26-4-2012 at 13:12

Problem solved. It was not chemophobia, by the way. I think that any fear I had was due to the fact that it could be a lot of bad things. I'm not just blindly saying bad things. The things in the jar could easily could be:

H₂SO₄
H₂S
H₂SO₃
SO₂
SO₃

Although I doubt sulfurous acid would have formed, the others are all toxic, corrosive, or both. I would rather be safe than sorry. Anyway, it was nothing dangerous. I opened up a plugged hole in the stopper and let it sit outside for a bit. Then I unplugged the stopper (which released a horrid and burning scent) but the scent faded quickly. I then cleaned it out and went about my day. I think it was H2S

woelen - 26-4-2012 at 22:20

The jar certainly could not contain SO3. This is incredibly reactive and cannot exist under any normal condition, where water is present. The others could indeed have been in the jar. But, given the small amounts, there was no reason at all to be afraid of them.

The goddess of chemistry must be treated with respect, but not with fear

weiming1998 - 28-4-2012 at 03:53

The sizzling is probably just water vaporizing as it hits the hot molten sulfur, the black residue some sort of contamination in your sulfur, and the brown-yellow an allotrope of sulfur. There would mainly be SO2 in the jar, but I could think of a potential side-reaction going on:
First H2SO3+S<===>H2S2O3 (the S2O3(-2) ion is produced by heating an aqueous solution of the SO3(2-) ion with sulfur, so maybe this would happen, but again this reaction is reversible, and because of the instability of the H2S2O3 in aqueous solution, it leans strongly to the left).
Then, in a worse case scenario, this: H2S2O3===>H2S+SO3 (not even sure if this could ever happen in the presence of water) and SO3+H2O===>H2SO4. But H2S is not a problem at all. It is readily destroyed by the SO2 being generated by the generator with the following reaction: 2H2S+SO2===>3S+2H2O. So the only thing in the jar, apart from SO2, is a tiny bit of dilute H2SO4. No deadly gases (apart from if your asthmatic, as SO2 irritates your lungs a lot and can cause an asthma attack) or corrosive substances (H2SO4 at that concentration, spilt on your hand, don't do much). The burning scent you smelled is definitely SO2, as H2S does not burn your nose but has a bad smell like sewers or rotten eggs.

In general, with gloves, goggles and a bit of care, even concentrated H2SO4 is nothing. There are much, much more dangerous substances out there. SO2 is an irritant to your lungs, but again it's nothing compared to some of the more toxic gases that chemists use. Doing this outdoors or in a fumehood is all you need.

If you only want dilute H2SO4, a substitute might be NaHSO4, or sodium bisulfate, found at pool stores for $15/3kg. It acts pretty much like dilute H2SO4, and is non-corrosive even in concentrated solutions. Only problem is that if you are making pure sulfate salts, it might a a bit difficult to separate the Na2SO4 from the desired sulfate. But otherwise, it's an OK substitute.