Sciencemadness Discussion Board

Sulphur dioxide from sulphuric acid

idrbur - 17-4-2017 at 06:33

Hey guys, i want to make Na2S2O5 for many experiments by bubbling SO2 from a solution of sodium carbonate but making SO2 by burning sulfur needs little setup and i can't make it from Na2S2O5 because as you know this ia what i want to make. So is there any method of making it directly from H2SO4 or making Na2S2O5 directly or indirectly from H2SO4.

Alice - 17-4-2017 at 07:03

Sulfur dioxide can be generated by treatment of sodium sulfite or sodium bisulfite with sulfuric acid.
Hope this helps.

Amos - 17-4-2017 at 07:05

Are you positive that there's no place where you live that you can simply buy sodium sulfite, bisulfite, or metabisulfite? Metabisulfites are one of the most commonly accessible amateur chemicals.

idrbur - 17-4-2017 at 08:50

Bro! I live in a small town in india and here finding even a most common chemical is like finding water in desert. So i have to make most of the chemicals on my own.:(
And thanks for replies.

[Edited on 17-4-2017 by idrbur]

Sulaiman - 17-4-2017 at 09:39

can you get Sodium thiosulfate ?
('hypo' in photographic circles).

not very efficient,
1 mole sulphuric acid + 1 mole sodium thiosulphate = 1 mole sulphur dioxide

Aqua-regia - 17-4-2017 at 10:59

If you have a plenty of sulfuric acid, and no else, boil this with common copper wire. You can get lot of SO2

ave369 - 20-4-2017 at 09:47

Yes, heating sulfuric acid with copper should do the trick. It should be concentrated.

pneumatician - 22-4-2017 at 16:34

you use this?

bluamine - 23-4-2017 at 02:35

If I still have a good memory, you can react it with tin to produce SnSO4, which decomposes at a relatively low temperature to give Sno2 with SO2

AJKOER - 24-4-2017 at 14:27

An interesting path mentioned in on SO2 is the action of H2 on H2SO4 at room temperature with time. To quote:

"Sulphuric acid is reduced to sulphur dioxide and water by prolonged contact with hydrogen at ordinary temperatures. The reaction is fairly rapid at 250° C."

Link: .

No heating, or any need for conc H2SO4, but an iron impurity in the sulfuric acid, I suspect, may help.

My speculation is that the reaction could proceed via a hydrogen atom radical and solvated electron pathway which could be sourced, for example, by photolysis in the presence of iron dust (see discussion at: ). Fine iron in air/water vapor could be a source of FeO, Fe2O3, FeOOH with the latter known to be photo active producing solvated electrons and hydroxyl radicals with H2O. Note, in the presence of H2SO4 and solvated electrons:

H+ + e-(aq) ---) .H (see, for example, )

With hydrogen gas and any formed hydroxyl radical:

H2 + .OH ---) .H + H2O

Also, per Atomistry it is reported that "finely divided iron decomposes acid of density 1.75 at 200° C., yielding the gas", but the action of light may remove the need for heating Fe/H2SO4 or H2/H2SO4 to produce SO2 gas.

One possible embodiment would be add a small amount of fine iron to H2SO4 in a collapsed large clear plastic bag resulting in situ H2 formation filling the bag and allowing also some surface iron contact. Place in sunlight. Caution: calculated the volume of H2 generated so make sure the vessel does not rupture splattering acid. Safety gear a must!

[Edited on 24-4-2017 by AJKOER]

[Edited on 25-4-2017 by AJKOER]