Sciencemadness Discussion Board - Sodium thiosulfate for hydrochloric acid production

Nurdrage heats sodium bisulfate with table salt to make hydrochloric acid in this video. Can I use sodium thiosulfate instead of sodium bisulfate for this? Thanks for your time.

https://www.youtube.com/watch?v=YGjd7xxTuZw

You can't use thiosulphate, how did you get that idea from the sulphur content in the name of the chemical?

Beezwax - 4-4-2023 at 13:18

You can't use thiosulphate, how did you get that idea from the sulphur content in the name of the chemical?

Yeah. Do you think it is worth using it to make sulphuric acid? I know I can mix it with weak acid and get so2. I accidentally bought some thiosuplhate and have absolutely no idea what to do with it.

Admagistr - 4-4-2023 at 13:34

Yeah. Do you think it is worth using it to make sulphuric acid? I know I can mix it with weak acid and get so2. I accidentally bought some thiosuplhate and have absolutely no idea what to do with it. [/rquote]

Yes,by decomposing Na2S2O3 with acid,I mean even weak organic acid,like citric acid,you can get SO2 and sulfur and you can oxidize SO2 and S to get SO3 and then H2SO4,but it's a long and laborious method of making H2SO4,which usually only leads to dilute H2SO4,you would have to boil it for a long time to get concentrated acid,this is is dangerous for acid ejection and SO3 release. The best thing to do is to buy H2SO4 for batteries and concentrate it by boiling...Na2S2O3 can be melted dry and then throw in a crystal of this compound,acetate heating bags work on the same principle,this is one example of how to use this compound...

[Edited on 4-4-2023 by Admagistr]

Beezwax - 4-4-2023 at 13:45

Thanks a bunch Admagistr, love ya

j_sum1 - 4-4-2023 at 14:58

There is a thread on ways to make H2SO4. IMO, electrolysis of copper sulfate is the simplest and most accessible.

Once you have concentrated sulfuruc acid, making HCl is a relatively straightfirward process. Pyrolysis of PVC is another route to HCl, but I believe it is really messy and is something of an engineering challenge.

I do not see anything sensible involving thiosulfate that will give you HCl.

Thiosulfate is actually pretty useful. I keep a spray bottle of thiosulfate solution on hand whenever I am working with oxidants like permanganates, dichromates or bromine. Neutralises and cleans up spills. It is a pretty nice reducing agent in its own right.

There is a classic high school experiment involving thiosulfate that you might want to do. Make up a solution and add an acid. After a short while the mixture will become turbid as sulfur orecipitates. If you control for volume and set your beaker on a black mark you can time (or video) until the mark is no longer visible. Adjusting temperature you can produce some nice data on temperature / reaction rate.

Beezwax - 4-4-2023 at 15:16

Quote:

Quote: Originally posted by j_sum1

There is a thread on ways to make H2SO4. IMO, electrolysis of copper sulfate is the simplest and most accessible.

I have some really fine copper motor wire. Do you think it would be economical to use the thiosulfste to turn that in to copper sulfate, by reacting with an organic acid, with the wire suspended above?

[Quote]Once you have concentrated sulfuruc acid, making HCl is a relatively straightfirward process. Pyrolysis of PVC is another route to HCl, but I believe it is really messy and is something of an engineering challenge.

I do not see anything sensible involving thiosulfate that will give you HCl.

Thanks

[Quote]Thiosulfate is actually pretty useful. I keep a spray bottle of thiosulfate solution on hand whenever I am working with oxidants like permanganates, dichromates or bromine. Neutralises and cleans up spills. It is a pretty nice reducing agent in its own right.

Awesome. Can it even make strong ones like lox or lo3 safe?

[Quote]There is a classic high school experiment involving thiosulfate that you might want to do. Make up a solution and add an acid. After a short while the mixture will become turbid as sulfur orecipitates. If you control for volume and set your beaker on a black mark you can time (or video) until the mark is no longer visible. Adjusting temperature you can produce some nice data on temperature / reaction rate.

Wonderful. Thx

teodor - 5-4-2023 at 04:28

Yeah. Do you think it is worth using it to make sulphuric acid? I know I can mix it with weak acid and get so2. I accidentally bought some thiosuplhate and have absolutely no idea what to do with it.

Thiosulfate ion is -S-SO3, so, as far as I remember, there is a method to decompose it to SO3 (not SO2). But this requires some complex not novice-level technique. (Probably you should get the free acid first which is stable only at low temperature or something like that)

[Edited on 5-4-2023 by teodor]

Admagistr - 5-4-2023 at 04:49

Thiosulfate ion is -S-SO3, so, as far as I remember, there is a method to decompose it to SO3 (not SO2). But this requires some complex not novice-level technique. (Probably you should get the free acid first which is stable only at low temperature or something like that)

[Edited on 5-4-2023 by teodor][/rquote]

One atom of oxygen binds sodium very tightly,do you want to reduce sodium metal from the compound??!Na2S2O3 can alternatively be written as Na2O.S.SO2.I can't imagine how such a reaction could be done,it seems completely unrealistic...

[Edited on 5-4-2023 by Admagistr]

teodor - 5-4-2023 at 09:23

One atom of oxygen binds sodium very tightly,do you want to reduce sodium metal from the compound??!Na2S2O3 can alternatively be written as Na2O.S.SO2.I can't imagine how such a reaction could be done,it seems completely unrealistic...

H2S2O3 → H2S + SO3

this is how the acid is decomposed in anhydrous conditions.
https://en.wikipedia.org/wiki/Thiosulfuric_acid

[Edited on 5-4-2023 b
Compare it with
H2SO4 -> H2O + SO3

The problem with getting SO3 out of the salt in water solution is that while S builds long chains (S8) and forms precipitate the anion is converted to sulfite:

(-S-S-S-S-S-S-S-S-SO3)2- -> S8 + (SO3)2-

Well, it is probably interesting experiment, to decompose thiosulfate without oxidation of one atom to sulfur, but it is far from both novice level and the original question.

... And it is not Na2O + ..., it is 2Na+ + (-S-SO3)2-

which is actually similar to

2Na+ + (-O-SO3)2- (sodium sulfate)

(and that is why it is "thiosulfate", not "thiosulfite")

[Edited on 5-4-2023 by teodor]

Texium - 5-4-2023 at 10:17

H2S2O3 → H2S + SO3

Would that not react further like:
H₂S + SO₃ —> H₂O + SO₂ + S ?

Somehow I doubt that H₂S and SO₃ like being around each other very much.

teodor - 5-4-2023 at 11:21

Quote: Originally posted by Texium

H2S2O3 → H2S + SO3

Would that not react further like:
H₂S + SO₃ —> H₂O + SO₂ + S ?

Somehow I doubt that H₂S and SO₃ like being around each other very much.

Admagistr - 5-4-2023 at 12:20

Quote: Originally posted by Texium

H2S2O3 → H2S + SO3

Would that not react further like:
H₂S + SO₃ —> H₂O + SO₂ + S ?

Somehow I doubt that H₂S and SO₃ like being around each other very much.

This is the very good question because it motivated me to find the answer:

"H2S2O3 -> H2S + SO3

Under anhydrous conditions the reaction products do not enter into a redox reaction, but are stable in contact with each other"

A. Senning, sulfur in organic and inorganic chemistry, volume 2, p.92".

So, thiosulfate should be interesting compound for experiments both for experienced and unexperienced chemist.

Theodore I see what you mean, if we are talking about anhydrous thiosulfuric acid and in anhydrous environment it is something completely different, I meant Na2S2O3, which is a hydrate and that is the problem... Do you have any info,how to make anhydrous H2S2O3,in some organic solvent that would not react with SO3 or H2S,is there any such thing?You would have to work in a perfectly dry environment.In solution the thiosulfate is ionized,so I understand your ionic notation,when I was thinking about the Na2O,I was thinking about an anhydrous compound.

[Edited on 5-4-2023 by Admagistr]

Admagistr - 5-4-2023 at 12:38

Thanks a bunch Admagistr, love ya

Thanks

! When you do an experiment, be sure to let know how you did, or write a plan and send a photo of the aparature or the experiment

...

teodor - 5-4-2023 at 15:00

Theodore I see what you mean, if we are talking about anhydrous thiosulfuric acid and in anhydrous environment it is something completely different, I meant Na2S2O3, which is a hydrate and that is the problem... Do you have any info,how to make anhydrous H2S2O3,in some organic solvent that would not react with SO3 or H2S,is there any such thing?

I think it's not hard to get anhydrous thiosulfate. As for the rest, several possibilities could be checked. I don't think I need to write details. If somebody can understand the chemistry involved its better to make an experiment and show the results than make speculations.

As for making sulfuric acid I think it's better to follow Nurd Rage or Adrian's chemistry lab methods. Also we have a thread "making H2SO4 in a home lab".

And for generating SO2 I think metabisulfite is the more economic way.

clearly_not_atara - 6-4-2023 at 07:13

Actually, that sounds like a great way to make SO3, since it can be condensed and is produced at a "relatively" low temperature. But the counterion of the acid you use to react with thiosulfate will likely react with SO3. So it would be better to do the rxn first at very low temperatures (<< -5 C) where thiosulfuric acid does not decompose, filter out the salt byproduct, and only then decompose H2S2O3. This was originally performed in ether over dry ice:

Quote:

Recently, Schmidt has prepared solutions of thio- sulfuric acid by the decomposition of sodium thiosulfate with HCl in ether at –78 C. A dietherate of thiosulfuric acid was obtained which decomposed at –5 C by reaction 39 (H2S2O3 >> H2S + SO3)

Very low temperatures are necessary because the undesirable product S8 is actually formed by polycondensation of the monoanion HS2O3- and does not require water, so the thiosulfate must be fully protonated before it is allowed to decompose.

Nitromethane is a compatible solvent for SO3, but may be reduced by H2S (not sure):
https://onlinelibrary.wiley.com/doi/abs/10.1002/recl.1968087...

Some solvents, including DMF, dioxane, benzonitrile and NMP, form complexes with SO3 that can be used as more easily handled SO3-donating agents, which may be preferable anyway:
https://pubs.acs.org/doi/pdf/10.1021/jo00814a026

Alternatively, liquid SO2 is a compatible noncomplexing solvent, though a very good setup would be required to perform the whole process.

But as far as sulfuric acid, it is a little more dangerous than necessary to be generating a lot of H2S. You would have better luck with lots of other options. For concentrating H2SO4, maybe reduced pressure distillation over sodium pyrosulfate would work?

EDIT: Forgot to include the original paper on thiosulfuric acid decomposition:

https://pubs.acs.org/doi/pdf/10.1021/ja01547a018

The mechanism of formation of S8 is actually pretty interesting in and of itself:

-S(n)SO3H + HSSO3H >> HS(n+1)SO3H + HSO3-

continuing until n = 8 at which point we see ring closure

[Edited on 6-4-2023 by clearly_not_atara]

Admagistr - 6-4-2023 at 15:11

@clearly_not_atara

Thanks for the very valuable information on this topic.

teodor - 9-4-2023 at 13:14

There is much simpler route from thiosulfate to sulfuric acid - by hydrolisis of cuprous thiosulfate.
This is just an example:

I. 10g CuSO4*5H2O in 50 ml of water @ 40C + 18g Na2S2O3 in 30ml of water @ 40C => 2Na2S2O3 * 3Cu2S2O3 * 6H2O (the yellow complex salt, precipitation after 1 hr).
II. 0.5g of the complex salt + 30 ml of water, boiling:

Cu2S2O3 + H2O = Cu2S + H2SO4

By adjusting concentration you can find the optimal process of getting H2SO4 solution.

Admagistr - 10-4-2023 at 12:49

There is much simpler route from thiosulfate to sulfuric acid - by hydrolisis of cuprous thiosulfate.
This is just an example:

I. 10g CuSO4*5H2O in 50 ml of water @ 40C + 18g Na2S2O3 in 30ml of water @ 40C => 2Na2S2O3 * 3Cu2S2O3 * 6H2O (the yellow complex salt, precipitation after 1 hr).
II. 0.5g of the complex salt + 30 ml of water, boiling:

Cu2S2O3 + H2O = Cu2S + H2SO4

By adjusting concentration you can find the optimal process of getting H2SO4 solution.

Thanks! But Cu2S,as far as I know reacts with H2SO4,how would you like to implement the reaction to prevent this?But maybe with dilute acid in the cold the reaction is very slow...

[Edited on 10-4-2023 by Admagistr]

teodor - 11-4-2023 at 00:18