I watched a video where SO2 was bubbled through 3% H2O2 to get H2SO4. From my understanding, only 3% of the solution is converted into H2SO4, the rest
being H2SO3. Am I right?
Any help is appreciated.
[Edited on 18-8-2012 by achem500]Adas - 18-8-2012 at 13:50
I watched a video where SO2 was bubbled through 3% H2O2 to get H2SO4. From my understanding, only 3% of the solution is converted into H2SO4, the rest
being H2SO3. Am I right?
Any help is appreciated.
[Edited on 18-8-2012 by achem500]
Yes.barley81 - 18-8-2012 at 15:22
The hydrogen peroxide, which is about 0.9M, reacts with SO2 and an 0.9M solution of sulfuric acid is formed, which is about 9% sulfuric acid by mass.
(this is if volume remains the same) Further bubbling of SO2 just results in saturation of the solution with the gas. H2SO3 cannot be isolated as a
pure substance, but there is some of it in a solution of SO2. Boiling the solution drives off the volatile SO2, leaving behind a solution of sulfuric
acid.AJKOER - 19-8-2012 at 17:00
I place of H2O2, consider using HOCl (from Cl2 and H2O, or other routes) as:
Cl2 + H2O <--> HOCl + HCl
H2SO3 + HOCl --> HCl + H2SO4
Source: See Watt's Dictionary Chemistry, Vol 2, page 16 where Watt's notes the ability of even dilute HOCl to oxidize H2SO3, H2S and even Sulfur to
H2SO4.
In the lab, a good procedure is to first treat water with SO2 and then Cl2. Repeat to concentrate. The volatile HCl can be largely removed by treating
the final solution with hot air.
In place of Hypochlorous acid, one could in theory use Ozone. However, I am not sure if an O3 generator would be efficient here as one is passing a
large quantity of mostly inert gas through H2SO3 that may simply strip SO2 from solution reducing yield.
Caution: The Hypochlorous acid route involves toxic fumes and can form dangerous concentrated acid (as water is consumed) so proceed only with proper
ventilation (fume hood, outdoors) and appropriate safety gear.
[Edited on 20-8-2012 by AJKOER]achem500 - 20-8-2012 at 02:36
