Sciencemadness Discussion Board

Hydrochloric acid synthesis via electrolisis

ThatChemist89 - 15-8-2024 at 12:39

In the electrolysis of H2O and NaCl Cl gas and H2 evolute if the 2 containers are separated by a ion exchanger cl gas is reacted with water to form HCL and hypochlorous acid while the other chamber will form NaOH were not focusing on NaOH a solution of about 50 50 hypochlorous acid and Hcl can be made how can the hypochlorous be turned into HCL? i know thermal decomposition but i have a alcohol lamp would that and a stainless steel pot be good enough?
i got information from
https://www.youtube.com/watch?v=T5PJjabZ2EE
https://www.youtube.com/watch?v=2-d4dIXQN78
but i need better clarification

woelen - 16-8-2024 at 04:51

Could you please try to use better punctuation and use of capital letters in your written texts? It is hard to understand your questions.

What I get from your post is that you want to make HCl by electrolysis of NaCl.

You want to collect the Cl2 gas into a separate container and dissolve that in water to make HCl and HOCl? Or do you want the HCl and HOCl to be formed directly in the salt solution? The latter will have the big disadvantage that you get very impure HCl.

But the mechanism of making HCl from Cl2 and water is not an easy and smooth mechanism anyway. You only can get very dilute solutions of Cl2 in water and heating is not practical, because it drives off all Cl2 and if you have HCl and HOCl in water, then heating causes the reverse reaction and Cl2 is driven out of solution.

Industrially, HCl is made from the H2 and Cl2. These are mixed (together with a lot of air in order to avoid explosively fast reactions) and reacted directly to HCl, which then is dissolved in water. This process leads to impure dilute HCl in which Cl2 is dissolved. The latter can be driven off by heating without boiling away the HCl.

If you want stronger HCl, then I would use swimming pool pH-minus (which is nearly pure NaHSO4.H2O), intimitely mixed with NaCl and gently heating the mix. Humid HCl fumes escape from this mix, which then can be passed through water. This works fairly well and can even be done in glass apparatus. pH-minus is available nearly everywhere, it is not regulated like H2SO4.

ThatChemist89 - 17-8-2024 at 07:07

Thanks for the response!

My idea is that the HCL and HOCL will be formed in the salt solution and distill it.

Wouldn't the HCL come over only?
because i know HOCl can decompose yielding 02 and HCL, but i also know that they can react (HOCl and HCL) so im stuck is that a good procedure to conduct the electrolysis and distill it?

EDIT: wouldn't the HCL come over with water only? (HOCl will decompose,NaCl will remain in the flask)


[Edited on 17-8-2024 by ThatChemist89]

EF2000 - 17-8-2024 at 08:44

Have you seen this: https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
All you need is a chloralkali cell with a membrane, UVC lamp and a little courage (it can potentially explode).

woelen - 18-8-2024 at 23:51

Quote: Originally posted by ThatChemist89  
Thanks for the response!

My idea is that the HCL and HOCL will be formed in the salt solution and distill it.

Wouldn't the HCL come over only?
because i know HOCl can decompose yielding 02 and HCL, but i also know that they can react (HOCl and HCL) so im stuck is that a good procedure to conduct the electrolysis and distill it?

EDIT: wouldn't the HCL come over with water only? (HOCl will decompose,NaCl will remain in the flask)


[Edited on 17-8-2024 by ThatChemist89]

Theoretically, you are right. You could distill HCl out of a solution of NaCl. Practically, things are not so simple. As EF2000 says, you need a membrane in your cell, separating the anode volume from the cathode volume. At the cathode you get hydroxide ions, and these would spoil your reaction completely. You also need to quickly decompose the HOCl and the process should not be too fast, otherwise the Cl2 escapes as gas from the solution (it is not that soluble, and in strong NaCl its solubility is even lower). So, if you do this as an academic exercise, then you definitely could give it a try, but if you really want a practical way of making HCl, then I strongly recommend other methods, such as the one, I mentioned in my previous post.

ThatChemist89 - 19-8-2024 at 13:48

Hello there! i did the electrolysis before haring your message and my product for some reason was sodium hypochlorite i will get H2SO4 and make HCL and not conduct electrolysis as i do not posses the correct equipment to do so.

woelen - 20-8-2024 at 00:04

If you don't have a membrane, then indeed you get sodium hypochlorite (and when the solution is warm, you get sodium chlorate). This is because at the cathode you get hydroxide ion, and this neutralizes any acid, formed indirectly from chlorine and water.