Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1    3
Author: Subject: SO2 Generator
weiming1998
International Hazard
*****




Posts: 616
Registered: 13-1-2012
Location: Western Australia
Member Is Offline

Mood: Amphoteric

[*] posted on 12-4-2012 at 17:31


Quote: Originally posted by dann2  

What impurities would Camden tablets (Sodium Metabisulphite for wine making) contain.
Would it effect SO2 making using the tablets + Sulphuric acid
Could other acids be used instead of Sulphuric?
Dann2


I don't know about impurities, but they wouldn't really matter that much. Most impurities probably won't affect the SO2 made, but that depends on what acids you use. If there is chlorides in your winemaking tablets, for example, and you use sulfuric acid, the resulting evolution of HCl gas will ruin your SO2.

Sulfuric acid isn't actually a good candidate acid for generating SO2, as other soluble gases generated might contaminate the SO2, and also the fact that SO2 dissolves in sulfuric acid more than water. So your best acid choice would be HCl solution, as that prevents the formation of hydrogen halides.

But almost all acids work (well, apart from a few exceptions that are extremely weak acids/oxidizing acids like HNO3, which will oxidize the SO2 produced to sulfuric acid, and HClO/H2CO3, which almost certainly doesn't work) by this equation: Na2S2O5(s/aq)+2H+(aq?)==>2SO2(g)+H2O+2Na+(aq). The SO2 exits the solution as a gas, making this reaction favourable, so even weak acids (like acetic acid) works. But not a dilute solution though (if you used vinegar, the yield will not be great compared to if you used 25% acetic acid.)
View user's profile View All Posts By User
dann2
International Hazard
*****




Posts: 1523
Registered: 31-1-2007
Member Is Offline

Mood: No Mood

[*] posted on 13-4-2012 at 03:46



Thanks for reply.
I might get around to trying it some time as I need to clear away all Chlorate from Perchlorate that I have using SO2.



View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 7777
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

[*] posted on 8-5-2012 at 23:49


After reading over this whole thread I now think that the formation of SO2 from H2SO4 and S maybe due to organic impurities in the S. This also could account for the black coloration of the acid, reported by some people. I did not know of that kind of impurities back in 2007, but recently I have seen some posts about sulphur from gardening suppliers containing organic impurities, leading to charring when the sulphur is heated. I also read that some sources of sulphur may contain small amounts of CaCO3, which also may cause bubbling (CO2).

I still am convinced that very pure sulphur and pure sulphuric acid only react with difficulty making SO2.




The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
View user's profile Visit user's homepage View All Posts By User
elementcollector1
International Hazard
*****




Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline

Mood: Molten

[*] posted on 30-1-2013 at 10:12


I saw you mentioned on the first page that your CrO3 decomposed to oxygen and a green Cr(III) compound. That was chromium (III) oxide. How did you make your CrO3 from K2Cr2O7 and H2SO4, anyway?

Also, for production of SO2 from sulfuric acid, what about electrolysis? This could even work for sulfates.




Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 7777
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

[*] posted on 31-1-2013 at 00:57


I did not isolate CrO3. This compound simply is formed when chromates or dichromates are mixed with conc. H2SO4.

E.g. K2Cr2O7 + 2H2SO4 --> 2KHSO4 + H2O + 2CrO3

This reaction also works with very concentrated solutions. E.g. if you prepare a saturated solution of Na2Cr2O7 and pour in conc. H2SO4, then a dark red slurry of CrO3 is formed. This material, however, is very hard to isolate.

For my experiment there was no need to isolate the CrO3, it simply was in solution and reacted with the sulphur.

-------------------------------------------------------------------------------------------------

Electrolysis of solutions of sulfates or aqueous sulphuric acid does not lead to formation of SO2. At the anode you get oxidation of the anode material, or formation of oxygen if the anode is inert and at the cathode you get hydrogen gas.




The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
View user's profile Visit user's homepage View All Posts By User
elementcollector1
International Hazard
*****




Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline

Mood: Molten

[*] posted on 31-1-2013 at 15:43


What makes it hard to isolate? Does filtration or decanting the excess liquid not work for whatever reason?



Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
View user's profile View All Posts By User
UnintentionalChaos
International Hazard
*****




Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline

Mood: Nucleophilic

[*] posted on 31-1-2013 at 16:07


Quote: Originally posted by elementcollector1  
What makes it hard to isolate? Does filtration or decanting the excess liquid not work for whatever reason?


Hygroscopic, corrosive, highly water soluble, sets a number of organic solvents on fire on contact. You need to remove the fairly concentrated sulfuric acid from the product somehow.




Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
View user's profile View All Posts By User
 Pages:  1    3

  Go To Top