Sciencemadness Discussion Board - easiest acid

easiest acid

helzblack - 3-7-2024 at 23:56

What is the easiest acid made by electrochemistry stronger than boric acid? Or can boric acid be made electrochemically?
I have been looking for a way to turn borax into boric acid and I am tired of having to buy acid, given that it is such weak acid is there any acid stronger than boric acid that can be made electrochemically?

My requirements are only otc reagents and no usage of lead or mercury. I have already thought of just making dilute sulfuric acid with sulfate salts or using hydrochloric acid, but is there any other acid that can be made in a reusable process like this?

Like use the acid to turn borax into boric acid then turn the salt of the acid back into the acid and repeat to make more boric acid with more borax

mackolol - 4-7-2024 at 00:06

Here ya go, two easy procedures for electrochemical synthesis of H2SO4 from scratch:
https://www.youtube.com/watch?v=6ms6xbPhdVs&ab_channel=N...
https://www.youtube.com/watch?v=5dUSF9Gl0xE&ab_channel=N...

Sulaiman - 4-7-2024 at 00:42

HCl is suitable, cheap and commonly available.

j_sum1 - 4-7-2024 at 00:54

Pool grade NaHSO4 should work for what you want to do.

helzblack - 4-7-2024 at 01:11

can sodium bisulfate be made electrochemically?
with respect to the other suggestions
I already knew about those ones, but are there other acids, other than sulfuric and hydrochloric that can be made by electrolysis?

Sulaiman - 4-7-2024 at 01:41

The pKa of boric acid is 9.24, 12.4, 13.3 (1st, 2nd, 3rd proton)
So I imagine almost any common acid would work?

PS try pH universal indicator papers with a boric acid solution... It's not a real acid

(yes, it's a Lewis acid, sometimes a Bronstead-Lowry acid - but it's sooo weak)

[Edited on 4-7-2024 by Sulaiman]

helzblack - 4-7-2024 at 02:05

i know, hence why using sulfuric is overkill, and why i am asking if there is any other acid that can me made electrochemically, that way i can turn arbitrarily large amounts of borax into boric acid.i dont want to buy new acid, but to use the acid to make boric acid from borax and use the salt of the acid to make more acid to make more boric acid from the borax ad infinitum. or at least to only have to introduce new acid from time to time.
what acids other than sulfuric and hydrochloric can be made electrochemically? that way my only inputs are borax and electricity, with a little acid from time from time, not need to get anything else

[Edited on 4-7-2024 by helzblack]

j_sum1 - 4-7-2024 at 03:19

You realise that electrochemistry is a slow way to produce acid. You are limited by Faraday's law and the maximum current your cell can handle.

But if that is how you wish to proceed, I would recommend copper sulfate to produce sulfuric acid. It is a straightforward process with few complications. Lead will work as an anode and the colour indicates progress.

That said, the product of precipitating boric acid will be a very dilute solution. The solubility of borax is not very high. With such low concentration, I don't know how practical it would be to recycle the sulfate ion. What happens to the sodium ions in the solution? I think electrolysis would merely yield oxygen and hydrogen without recovering acid. Off the top of my head I can't think of an anion that would work - at least not without a membrane.

If cost is a factor, then you are lookjng for an acid with the best price in terms of moles of H+ per dollar.where I live, that is pool acid. HCl concrete cleaner is second and cheap vinegar third.

bnull - 4-7-2024 at 05:01

Electrolysis with a membrane: İffet Yakar Elbeyli, Abdullah Zahid Turan, İ. Ersan Kalafatoğlu, "The electrochemical production of boric acid" (https://doi.org/10.1002/jctb.4496).

khlor - 4-7-2024 at 07:12

So, you want acid by electrolysis, well, know that I speak from experience, however little it may be.

sulphuric acid can easily be made from a single cell using copper sulphate, a graphite anode(positive electrode) and a copper cathode(negative electrode) and it give good results, after the solution clears you need to filter out the copper and graphite particles and boil it of to concentrate further the sulhpuric acid.

one thing I found out is that imposing a current limit on the cell helps to redude the graphite anode erosion.

now for sulphuric acid using other methods, there is electrodialysis... you can check out the "Scrap Science" channel on youtube, he does a good work on showing how it can be done(it is slow, but doable, I had some decent results and low power consumption from what my tests show.

he uses epson salt, but I think it to be expensive, you could use sodium sulphate,however I am cheap, very cheap, so I used plaster(Calcium Sulphate) to react with sodium hydroxide to form sodium hydroxide, then once the process finish, you can reuse the resulting sodium hydroxide solution to leach sulphate ions from Calcium Sulphate. it is my believe that the same can be done with some other oxyacids, like phosphoric acid, and maybe even some hydracids(with lower success) so long as you have a very soluble ions source. and from what I gathered electrodialysis works in a similar way to electrostatic attraction and all you need is an ion exchange membrane or something that can works as a diaphragm(yes it has to be a divided cell)

It has been a while since I made experiments such as these and my battery of experiments and tests was left incomplete due to personal reasons. I did had success in making HCl, in low concentration because the anode of the electrodialysis cell starts forming chlorine gas.

the crude solution for sulphuric acid experiments yielded roughly 12% w/v concentration, test done by titration using cheap pH strips to sort of have an idea where was the pH level, so take it with a grain of salt.

helzblack - 4-7-2024 at 17:20

Quote:

Electrolysis with a membrane: İffet Yakar Elbeyli, Abdullah Zahid Turan, İ. Ersan Kalafatoğlu, "The electrochemical production of boric acid" (https://doi.org/10.1002/jctb.4496).

Thanks bnoll. I will check it out

Quote:

so I used plaster(Calcium Sulphate) to react with sodium hydroxide to form sodium hydroxide

but given the insolubility of calcium sulfate wont than stop the formation of sodium sulfate?

or you mean to mix a slurry of calcium sulfate with sodium hydroxide and use that in the divided cell?

khlor - 5-7-2024 at 07:48

Quote: Originally posted by helzblack

Quote:

Electrolysis with a membrane: İffet Yakar Elbeyli, Abdullah Zahid Turan, İ. Ersan Kalafatoğlu, "The electrochemical production of boric acid" (https://doi.org/10.1002/jctb.4496).

Thanks bnoll. I will check it out

Quote:

so I used plaster(Calcium Sulphate) to react with sodium hydroxide to form sodium hydroxide

but given the insolubility of calcium sulfate wont than stop the formation of sodium sulfate?

or you mean to mix a slurry of calcium sulfate with sodium hydroxide and use that in the divided cell?

Sorry, I mistyped, I used Calcium sulphate to react with sodium hydroxide to form sodium sulphate and Calcium hydroxide, the reaction is pretty straight forward, a simple displacement reaction, it is messy you will have to do a mix in a slurry, like you already summarized. then you allow the slurry to sit for a while and take the solution which will contain sodium sulphate and put that on on the divided cell, for voltages I did use 3V, 5V and even 15V my results do not show changes in speed but do increase anode erosion. the reaction is slow, don't expect anything too speedy. my experiments lasted weeks. though I imagine that in a week or so you might have some decent results(that might be a matter of opinion though, for me decent was the formation of acid in the anode chamber however dilute it may be).

Note: make sure to stir the slurry of calcium sulphate and sodium hydroxide very well. and take only the water portion of the solution. if you used equimolar parts of sodium hydroxide and calcium sulphate, the solid part should be only calcium hydroxide with traces of calcium sulphate. and the clear solution should be sodium sulphate. make sure to do the math on the reactions in order to efficiently perform the operation and not waste any reagents. I have not tested, but it is my believe that instead of sodium hydroxide, you could use sodium bycarbonate or even sodium carbonate, however, I have not tested that.

[Edited on 5-7-2024 by khlor]