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S02 gas

seawolf - 24-8-2011 at 18:35

Somewhere I read a formula for generating S02 gas using copper scrap and an acid. CRS has struck again and I can't find it again. Any help would be good.
Mark

redox - 24-8-2011 at 18:40

You can generate sulfur dioxide by the reaction of sulfite, bisulfite, or metabisulfite salts with an acid. This is because the sulfurous acid forms and then quickly decomposes into sulfur dioxide and water.

2HCl + Na2SO3 ---> 2NaCl + H20 + S02

HCl + NaHSO3 ---> NaCl + H2O + SO2

2HCl + Na2S2O5 ---> 2NaCl + 2SO2 + H20

It is made by burning elemental sulfur.

S8 + 8O2 ---> 8SO2

It is also formed by the pyrolysis of metabisulfite.

Na2S2O5 ---> Na2O + 2SO2

Why do you need SO2 gas?

[Edited on 25-8-2011 by redox]

[Edited on 25-8-2011 by redox]

[Edited on 25-8-2011 by redox]

#maverick# - 24-8-2011 at 19:21

Are you trying to make h2so4. You could lead so2 to h2o2

MeSynth - 24-8-2011 at 20:54

You can get it by burning sulfer. Easiest way. Nurdrage demonstrates how this can be done in one of his youtube videos. youtube.com/nurdrage

zhaokenb - 24-8-2011 at 22:17

I'm new here

I think it's what you want,maybe
Cu+2H2SO4 ---△ →CuSO4+SO2↑+2H2O,and it should be oil of vitriol,or it won't react

woelen - 24-8-2011 at 23:06

Yes, the latter is a known (but not the best) method for making SO2.

If you have conc. H2SO4, then a much better method is to dilute this acid somewhat (to appr. 50%) and then add the warm acid to solid Na2S2O5 or K2S2O5 (sodium or potassium metabisulfite, available from suppliers who sell stuff for making wine and beer brewing). The SO2 simply bubbles from the solid, and if the reaction becomes somewhat sluggish, just heat gently.

White Yeti - 25-8-2011 at 01:00

Buying sulfur off of the interwebs and then burning it in air will yield SO2. You can separate this gas from nitrogen by cooling to -10C, The SO2 will condense while the nitrogen remains as a gas. I though that was a neat way to obtain resenably pure SO2(l). It gets so cold where I live that I can leave it outside overnight in winter and it will condense. Be careful!! If you have asthma, SO2 will knock the air clean out of your lungs for at least 10 minutes (talking from experience).

Mildronate - 25-8-2011 at 02:23

Its not economical burnig sulfur. Better use Na2SO3 or Na2S2O5.

bbartlog - 25-8-2011 at 06:09

Quote: Originally posted by Mildronate

Its not economical burnig sulfur. Better use Na2SO3 or Na2S2O5.

Not *economical*? It may be messy, but your objection is bizarre. In the first place, sulfur is cheaper than sodium bisulfite; maybe $6/lb versus $9/lb even in small quantities, and in bulk the price of sulfur drops to less than $0.20/lb (though that is for multiton quantities... I expect $1/lb is as low as you will get for amounts you can lift).
But further, look at the stoichiometry: you need three times as much weight of Na2SO3 for each equivalent of SO2 as you would of sulfur. So unless you have a source for bisulfite that offers it for about $0.30 per pound this is simply wrong.

woelen - 25-8-2011 at 06:17

But there also is another thing. From Na2SO3 or Na2S2O5 you get really pure and concentrated SO2, it's like bubbling CO2, made by adding acid to Na2CO3. I see this as a big advantage. Making SO2 with these chemicals is as easy as making CO2 from Na2CO3.

redox - 25-8-2011 at 06:23

One disadvantage for burning sulfur to generate SO2 is the fact that it is difficult to lead the SO2 gas into a reaction chamber, unless one has a vacuum, which many do not have access to.

You can't seal the burning vessel, unless you mix an oxidizer with the sulfur. At this point, it might actually be economical to just use metabisulfite, instead of potassium nitrate or chlorate and sulfur.

White Yeti - 25-8-2011 at 10:37

Solution to these problems: liquefying the gas ensures high purity and usability.
I don't like the sodium metabisulfite method because it's so expensive for the amount of gas it generates. I burn sulfur in air and liquefy the mixture of gases. I then collect the liquid and store it in a lab freezer. Works well enough for me.
An added advantage to this method is that significant reaction pressures can be reached simply by letting the SO2 boil. If you are trying to make sulfur trioxide for example, high pressures drive the equilibrium more to the SO3 side, increasing yield, without even using a pump

redox - 25-8-2011 at 10:40

Quote: Originally posted by White Yeti

Solution to these problems: liquefying the gas ensures high purity and usability.
I don't like the sodium metabisulfite method because it's so expensive for the amount of gas it generates. I burn sulfur in air and liquefy the mixture of gases. I then collect the liquid and store it in a lab freezer. Works well enough for me.
An added advantage to this method is that significant reaction pressures can be reached simply by letting the SO2 boil. If you are trying to make sulfur trioxide for example, high pressures drive the equilibrium more to the SO3 side, increasing yield, without even using a pump

Do you use dry ice/acetone or is a salted ice bath sufficient to reach SO2's boiling point of -10?

White Yeti - 25-8-2011 at 11:01

Quote: Originally posted by redox

Do you use dry ice/acetone or is a salted ice bath sufficient to reach SO2's boiling point of -10?

I am "fortunate" enough to live in a place where the temperature drops below -15C during the night in winter. I simply leave the mixture outside during the night to allow the SO2 to condense. I think an ethylene glycol/water bath should be sufficient. Just leave the mixture in the freezer and make sure there nothing else in the freezer. That way, most of the energy will go into removing heat from the ethylene glycol/ water bath, not into lowering the temperature of everything in the freezer. In any case, -10C is nothing a rankine heat pump can't handle. Dry ice is a bit extreme, a salt bath is good as long as you use ammonium chloride. It will enable you to reach -18C.

redox - 25-8-2011 at 12:40

Is there a specific reason why ammonium chloride allows lower temperatures than, say, sodium chloride?

The WiZard is In - 25-8-2011 at 13:20

Quote: Originally posted by seawolf

Somewhere I read a formula for generating S02 gas using copper scrap and an acid. CRS has struck again and I can't find it again. Any help would be good.
Mark

Sulphur Dioxide Provides Fascinating Home Experiments
Popular Science Science Monthly March, 1936

http://preview.tinyurl.com/SO2-Pop-Sci-1936

I'm so old — I Fart Dust and remember when SO2 was the
refrigerant in home refrigerators.

White Yeti - 26-8-2011 at 07:18

redox: All I know is that the freezing point of an ammonium chloride salt bath determines the "0" on the Fahrenheit scale. Thus you can rest assured it gets cold enough to condense sulfur dioxide. You can experiment with calcium and sodium chloride (which might get cold enough as well), but ammonium chloride will definitely work.

MrHomeScientist - 26-8-2011 at 13:55

Quote: Originally posted by The WiZard is In

Quote: Originally posted by seawolf

Somewhere I read a formula for generating S02 gas using copper scrap and an acid. CRS has struck again and I can't find it again. Any help would be good.
Mark

I found this pretty amusing: down on p. 94 there's an ad for "Science Discovers New Way to Increase Weight" - it "is putting pounds of solid, normally attractive flesh on thousands of 'skinny', run-down people who never could gain an ounce before."

You'd never see something like that these days!

The WiZard is In - 26-8-2011 at 15:48

Quote: Originally posted by MrHomeScientist

Mark[/rquote]

I found this pretty amusing: down on p. 94 there's an ad for "Science Discovers New Way to Increase Weight" - it "is putting pounds of solid, normally attractive flesh on thousands of 'skinny', run-down people who never could gain an ounce before."

You'd never see something like that these days!

You wouldn't see this in today's Popular Science either....!

February 1938.
http://tinyurl.com/Pop-Sci-Sci-Studies-Nudists

IrC - 26-8-2011 at 20:40

The wiki article is lacking somewhat. The Monitor-Top killed enough families they mostly quit SO2 and dabbled with ammonia for a while (when they leaked it drove people out of the building quickly even if they were asleep when the leak occurred), some of which still ran into the mid 60's. I grew up in the largest refrigeration repair business in Kansas City and remember the tanks of ammonia and SO2 gas, which I kept until they went up in a fire in the 70's. Freon was known and used for safety reasons but until the late 50's was still very expensive. Only the wealthy had units running freon for a lot of years. The cheap units were ammonia, bad because they abounded in packed tenements just asking for disaster. By the mid 60's I only used my SO2 tanks to flush the moisture from freon units when I was rebuilding them. It worked very well for this. Acid formed in the system would eat small patches inside only microns deep so it was not harmful at all. But dried the hell out of the insides of the unit better than any other method I ever used. By 1965 I was buying 50 LB tanks of R12 and R22 for around 17 dollars. R22 was a couple dollars more per tank.

kryss - 27-8-2011 at 08:50

And classified adds offering chems to the home experimenter!

SO2 Popular Science October 1942

The WiZard is In - 27-8-2011 at 09:44

Home Experiments Explain the Magic of Cold from Chemistry

http://tinyurl.com/SO2-Pop-Sci-Oct-1941

[Edited on 27-8-2011 by The WiZard is In]

AJKOER - 27-8-2011 at 15:13

OK, an old reference from Watt's Dictionary of Chemistry notes that HClO will oxidize Sulfur to form H2SO4, so one can avoid the generation of the SO2.

2 HClO + S + H20 --> H2SO3 + 2 HCl

HClO + H2SO3 --> H2SO4 + HCl

Note, HCl and HClO may also liberate some Chlorine gas as:

HClO + HCl <---> H2O + Cl2

Note, I do not expect the creation of any sulfuryl chloride, SO2Cl2, but if it is formed, it reacts violently with water:

2 H2O + SO2Cl2 --> 2 HCl + H2SO4

PREPARATION OF HClO:
HClO can be made by adding a weak acid, like acetic acid (or HAc of which vinegar is dilute variety) to bleach (Sodium hypochlorite, NaClO):

NaClO + HAc --> NaAc + HClO

Distill off half of the solution to nearly double the concentration of the HClO as HClO vapor and Cl2O come over mostly first during the distillation process. Use promptly as anything but dilute solutions will disproportionate:

3 HClO ---> 2HCl + HClO3

and to a much less extent, a decomposition reaction:

2 HClO --> 2 HCl + O2

MeSynth - 28-8-2011 at 12:55

Quote: Originally posted by Mildronate

Its not economical burnig sulfur. Better use Na2SO3 or Na2S2O5.

I dont know what you smokin but word on the street is I can buy a 5 pound bag for 8 bucks at my local plant nursery. It's 80% stuff but is easily purified by grinding and washing with water. Just hook a funnel to tube connected to a glass rod inserted through a cork or rubber stopper. The glass tube is positioned so that it is at the bottom of the flask so that when gas enters its bubbled through the mixture. Then another glass tube is inserted in the cork or rubber stopper and and tube connected to it and then the tube is connected to a source of vacuum. The second glass tube is positioned in such a way that it does not come near the liquid and is used to pull air through the liquid. Next step is place some sulfer on something that it will burn safly on and light it. Turn on the vacuum. Position the funnel over the burning sulfer. Cheap. Easy. Fun.

You can add a water bath to the pull setup to catch any particals followed up by a drying tube and even bubble it through sulfuric acid.

White Yeti - 1-9-2011 at 14:40

MeSynth:
Better change that mood of yours before you start tearin' up the dance floor

AJKOER - 7-9-2011 at 10:54

For those having trouble either freezing the SO2 or forcing it into a solution of H2O2 to create H2SO4, I would suggest a closed system approach involving the convenient generation of H2S from Sulfur and Aluminum scraps.

Caution: Perform outdoors given the broad range toxicity (including skin absorption) of H2S (similar to HCN) that might occur in the event of a leak and the smell of H2S is usually unappreciated by yours neighbors. Note, H2S gives an initially powerful odor followed by a deadening of ones sense of smell increasing its ability to induce a fatal dose with a characteristic delayed fatality effect. Have Bleach (NaClO) on hand to neutralize the reaction if the need arises.

Step1. Heat powdered Al and S to form Al2S3. Avoid exposing the Aluminum sulfide to moisture.

2 Al + 3 S --> Al2S3

Step 2. When ready add water and heat to generate a flow of H2S:

Al2S3 + 6 H2O --> 2 Al(OH)3 + 3 H2S

Step 3. Capture the H2S in H2O2:

H2S + 4 H2O2 --> H2SO4 + 4 H2O

Note, one may find adding an air pump to the H2O2 solution may help in oxidizing the H2S although aeration by itself is known to be effective in only low H2S concentrations.

Note, insufficient H2O2 yields Sulfur as does treating H2S with NaClO:

H2S + H2O2 --> S + 2 H2O
H2S + NaClO --> S + H2O + NaCl

Step 4. Depending on the hardware design, one could burn any excess unabsorbed H2S in air or direct into a Bleach (NaClO) solution. One could also collect the SO2 from the H2S combustion for adding to the product of Step 3.

2 H2S + 3 O2 --> 2 SO2 + 2 H2O

Obvious problem with this method (other than dealing with the smell) is the generally dilute H2SO4 formed.

For those lacking a source of Al, heat a mixture of sulfur and paraffin wax to form H2S.

[Edited on 8-9-2011 by AJKOER]

Gui316 - 15-9-2011 at 11:03

I've tried to oxidize sulfur in a vaccum flask with potassium nitrate, but it did not worked. Then I tried to oxidize it with calcium hypochlorite. It worked! I lead it to hydrogen peroxide and it turned yellow...Why? Also, I've split some molten sulfur on my microwave. It have solidified and I don't know how to clean that mess...Ideas?

watson.fawkes - 15-9-2011 at 12:45

Quote: Originally posted by Gui316

Also, I've split some molten sulfur on my microwave. It have solidified and I don't know how to clean that mess...Ideas?

Toluene. You may have some trouble keeping the toluene in contact long enough to dissolve the sulfur. Be creative. A cloth and wick-into-reservoir system might work.

AJKOER - 15-9-2011 at 18:09

Mixing Sulfur and Ca(OCl)2 is really only fun to watch and too dangerous to perform oneself. On YouTube:

http://www.youtube.com/watch?v=52wqqz0YKO8

Super heating the Sulfur in the rapid exothermic reaction with Ca(OCl)2 most likely generates Sulfur vapor, some SO2 and perhaps some Cl2 and sulfuryl chloride, SO2Cl2.

A better and safer idea, make HClO by mixing an aqueous weak acid (capable of forming a soluble calcium salt) with the Ca(OCl)2 Bleaching Powder. Distill to obtain pure HClO. Add Sulfur to form HCl and H2SO4 per the reaction scheme I previously noted.

Note, Carbonic acid, H2CO3, forms an insoluble CaCO3, so avoid. It is noted that the reaction with Ca(OCl)2.CaCl2 (Bleaching Powder) and CO2 liberates Chlorine (reference Wikipedia as one source), while Cl2 is not created with the reaction of NaClO and H2CO3, just HClO. My attempt at the reaction sequence:

H2CO3 + Ca(OCl)2 --> CaCO3 (s) + 2 HClO

Sufficient dilute HCl could also be created from:

H2CO3 + CaCl2 <---> CaCO3 (s) + 2 HCl

So as to produce Chlorine from:

HCl + HClO <---> Cl2 + H2O

[Edited on 16-9-2011 by AJKOER]

[Edited on 16-9-2011 by AJKOER]

[Edited on 16-9-2011 by AJKOER]

Gui316 - 16-9-2011 at 08:50

I don't think that HOCL can be distilled. It would decompose. Maybe using a vaccum distillation....But I don't think so. But I'll give it a try. What acid you think that I should use?

Gui316 - 16-9-2011 at 11:43

Just more one thing. You said that burning sulfur in presence of calcium hypochlorite yield sulfur vapors, sulfur dioxide and some sulfur-chlorine compounds. I've tried to make an solution of calcium hypochlorite and then I add sulfur to it. The reaction takes a while to get going, but once it does, it is a quite interesting reaction. I think that once the reaction takes place into water, it will not get very hot. Max 100 degrees. That would avoid formation of sulfur vapors and the formation of sulfuryl chloride, am I right? And...What does sulfur dioxide smells like? I tried to burn it, and it release a puggent smelling gas...Makes you feel pain in your noise and it actually reassemble the smell of chlorine...or maybe the smell of nitrogen dioxide...is it correct?

White Yeti - 17-9-2011 at 06:10

Quote: Originally posted by Gui316

And...What does sulfur dioxide smells like? I tried to burn it, and it release a puggent smelling gas...Makes you feel pain in your noise and it actually reassemble the smell of chlorine...or maybe the smell of nitrogen dioxide...is it correct?

Did it also sting your eyes? I accidentally got a whiff of that stuff, it burns your nose, it burns your eyes and it will close up your bronchi if you inhale too much of it. Oh, and it also kills your nerve cells in your nose that allow you to smell, so don't try to inhale it on purpose. It's nasty stuff, watch out.

Endimion17 - 17-9-2011 at 07:17

If you want to know the smell of sulfur dioxide (and you simply must, those are the basics), take a pinch of sulfur and set it on fire for a few seconds, then extinguish it and disperse the smoke with your hand. You'll notice a "smell of burning sulfur". There's no other better description. It doesn't smell anything like the halogens or nitrogen dioxide.
You can dissolve some potassium metabisulfite in few mL of water and take a whiff or two. It hydrolizes and produces the dioxide gas.

Given the amounts produced, there's no danger of injuring or killing yourself. At higher concentrations and prolonged exposure (it's easy to overexpose yourself and get symptoms later), it causes a great deal of pain upon lung dilatation during breathing and induces a shitload of coughing. Painful coughing. Worse than chlorine. This one just makes you cough and cough, and your bronchi try to close.
Eye stinging comes at even greater exposures, or if a streak of smoke touches your eyes.

It's not very toxic per se, but it is very, very irritating for the mucous tissues, and has somewhat delayed effects.
I was exposed to it for the first time when I was in junior elementary school. My grandpa used it in his vineyard and I remember stricking a match and, while it was just starting to burn, sticking it into a small pile of sulfur. And then I inhaled. After my bronchi dilated back

, I though to myself: "This is a hell lot of fun!"

Here's a nice set of photos by famous photographer Grunewald at Ijen in Indonesia. I can imagine how their lungs look like. Their teeth corrode, too, because they use a wet cloth in their mouth to breathe through. Poor people.

[Edited on 17-9-2011 by Endimion17]

White Yeti - 17-9-2011 at 09:08

Those pictures are breathtaking!!
Thanks for sharing.
I warned Gul316, not because sulphur dioxide is excessively dangerous, but because some people are more sensitive to it than others. I'll get a little personal, but I burned less than a gram of sulphur just to know what SO2 smelled like (and to see a nice blue flame), and a streak of smoke touched both my eyes and nose. Just that little bit of gas was enough to close up my lungs for several minutes and induce wheezing for several hours afterward. I have some symptoms of asthma but I never though sulphur dioxide would affect my lungs that much. I was more careful with sulphur ever since

Gui316 - 17-9-2011 at 12:24

Cannot be worse than chlorine. Chlorine fills your lung with fluid and cut your lung's capacity by maybe 70%. You try to cough, but you can't because there isn't enough air to cough. Ah well...That is weird, because I've burned sulfur here, and it smell like chlorine or nitrogen dioxide...Something between both. I'll try to do it with the metabisulfite, if I can get my hands on it. Just more one thing. Burning sulfur in presence of platinum would yield sulfur trioxide?

Endimion17 - 17-9-2011 at 12:43

Oh well, chlorine allows you to crawl on the floor and try to calm down by recovering yourself with small breaths at the time. Sulfur dioxide will painfully choke you to death and won't let you calm down because you won't be able to stop coughing, and inhaling will be very painful. There's no accounting for taste.

Either your olfactory system is damaged, or it wasn't just sulfur. The smell of SO<sub>2</sub> does not relate to halogens, which relate to nitrogen dioxide nd ozone. Those are two distinctive groups. Oxidizers and a reducer. Halogens smell like cleanliness, hospitals and analogue 35mm film canisters, and sulfur dioxide smells like volcanoes, strucked pieces of pyrite and medieval image of hell.

White Yeti, people with pulmonary issues tend to react more dramatically, that's true.
Yes, photos are amazing. Makes me want to take a small boat and go around the 0.5 pH acidic lake, like this man did.
Metabisulfite is extremelly common where I live. It's usually in regular stores, next to gelatin, vanilla, baking soda, etc. People put it in homemade jams and grape must. It's a cheap and
great antioxidant.

How would you burn sulfur in presence of platinum? That's not so easy to achieve. Just putting a piece of Pt in a jar with burning sulfur won't help.

[Edited on 17-9-2011 by Endimion17]

Gui316 - 17-9-2011 at 13:43

(un)Fortunately we don't have volcanos here in Brazil...I guess that this country is one of the worst countries for those who are in love with chemistry...Well...Is there any test for sulfur purity? My olfactory system seems to be fine...Well, since my problem with chlorine, i think that I'm more sensitive to it, but i don't think that it would make me identify chlorine smell from...sulfur. Well, burning that yellow powder really produces a white smoke that smells like nitrogen dioxide. I'm very disapointed to know that my sulfur is not as pure as I thought that it was...