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seawolf
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[*] posted on 24-8-2011 at 18:35
S02 gas


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
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[*] posted on 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]




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[*] posted on 24-8-2011 at 19:21


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



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[*] posted on 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
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[*] posted on 24-8-2011 at 22:17


I'm new here:D
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
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[*] posted on 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.




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[*] posted on 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).
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[*] posted on 25-8-2011 at 02:23


Its not economical burnig sulfur. Better use Na2SO3 or Na2S2O5.
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[*] posted on 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.
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[*] posted on 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.




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[*] posted on 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.





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[*] posted on 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:)
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[*] posted on 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?




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[*] posted on 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.
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[*] posted on 25-8-2011 at 12:40


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



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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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



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.


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!
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[*] posted on 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

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[*] posted on 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.



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[*] posted on 27-8-2011 at 08:50


And classified adds offering chems to the home experimenter!
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[*] posted on 27-8-2011 at 09:44
SO2 Popular Science October 1942


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]
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[*] posted on 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
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[*] posted on 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. :)
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[*] posted on 1-9-2011 at 14:40


MeSynth:
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