Sciencemadness Discussion Board

HOCl → HCl

Romix - 17-9-2024 at 12:23

Hello Dear forum members. Have interesting question for you.
How to decompose HOCl into HCl? Both are products of bubbling Cl2 into water. I need HCl, not much of it and taking my whole distillation setup 3k miles away is just stupid to make couple hundred ml, electrolyte is available there. Wiki saying you could use catalyst like Copper or Nickel oxides while bubbling Cl2 into water. I think it is nonsense, both acids will react with them, sure HCl will!!!!



[Edited on 17-9-2024 by Romix]

clearly_not_atara - 17-9-2024 at 17:15

What you are asking is a violation of thermodynamics. The reaction:
2 Cl2 + 2 H2O << >> O2 + 4 HCl
leans significantly to the left below about 900 C, as determined by the Gibbs energy. You can chlorinate various metals and then hydrolyze the chlorides. The sequence:
2 Cl2 + 2 MgO >> O2 + 2 MgCl2
MgCl2 + H2O >> MgO + HCl
is thermodynamically favorable at 500 C with removal of the products thanks to Le Chatelier's principle, but it is not exactly easy to run.

Alternatively, HCl can be obtained directly by heating MgCl2 hydrates. This is probably the easiest method to obtain HCl without needing to mess with chlorine. The decomposition temperature is a little bit on the high side (300 C?) but the process is clean and simple.





Romix - 17-9-2024 at 17:50

Quote: Originally posted by clearly_not_atara  
What you are asking is a violation of thermodynamics. The reaction:
2 Cl2 + 2 H2O << >> O2 + 4 HCl
leans significantly to the left below about 900 C, as determined by the Gibbs energy. You can chlorinate various metals and then hydrolyze the chlorides. The sequence:
2 Cl2 + 2 MgO >> O2 + 2 MgCl2
MgCl2 + H2O >> MgO + HCl
is thermodynamically favorable at 500 C with removal of the products thanks to Le Chatelier's principle, but it is not exactly easy to run.

Alternatively, HCl can be obtained directly by heating MgCl2 hydrates. This is probably the easiest method to obtain HCl without needing to mess with chlorine. The decomposition temperature is a little bit on the high side (300 C?) but the process is clean and simple.






Thank you for your reply Dear, very useful information.
300C+ is like boiling point of H2SO4, would English Quickfit glass handle this temperature increasing it slowly from room temperature or you have no experience with it, maybe someone else here have?
In case if distillation isn't available, is there any way of decomposing HOCl into HCl, I heard sun lights decomposing it, what are they UV or what?

averageaussie - 17-9-2024 at 18:21

Quote: Originally posted by Romix  
In case if distillation isn't available, is there any way of decomposing HOCl into HCl, I heard sun lights decomposing it, what are they UV or what?

The presence of light or transition metal oxides of copper, nickel, or cobalt accelerates the exothermic decomposition into hydrochloric acid and oxygen
https://en.wikipedia.org/wiki/Hypochlorous_acid#Formation,_s...

Romix - 17-9-2024 at 18:26

Quote: Originally posted by averageaussie  
Quote: Originally posted by Romix  
In case if distillation isn't available, is there any way of decomposing HOCl into HCl, I heard sun lights decomposing it, what are they UV or what?

The presence of light or transition metal oxides of copper, nickel, or cobalt accelerates the exothermic decomposition into hydrochloric acid and oxygen
https://en.wikipedia.org/wiki/Hypochlorous_acid#Formation,_s...

Yes, I've read it, not trusting Wiki, proved that lies are written there many times to myself!
Oxides will react with HCl, told it already here! Even if acid will be left, distillation needed to isolate it from all transition metal Chlorides!!!! Metal anions in acid is no good!

[Edited on 18-9-2024 by Romix]

averageaussie - 17-9-2024 at 19:01

hmm, alright then.
maybe you could evaporate the solution, eventually decomposing the HOCl into HCl and oxygen? HOCl is unstable in solution, you might be able to break the equilibrium with some heat.

Romix - 17-9-2024 at 19:22

Quote: Originally posted by averageaussie  
hmm, alright then.
maybe you could evaporate the solution, eventually decomposing the HOCl into HCl and oxygen? HOCl is unstable in solution, you might be able to break the equilibrium with some heat.

I thought about it, HCl fumes, doubt, all will escape boiling...
With reflux maybe possible.

Romix - 17-9-2024 at 19:34

No testing papers exist for testing concentration of HOCl, even for presence I think none or there is?
There are for Chloride! I have many.
What about testing solution after bubbling lots of Cl2 into it before placing it in a sunny place and few months after, having eye on it, making sure no one adds acid to it to wind me up.

averageaussie - 17-9-2024 at 20:01

Quote: Originally posted by Romix  

I thought about it, HCl fumes, doubt, all will escape boiling...
With reflux maybe possible.

You could probably use an inverted funnel placed underwater to dissolve the gaseous HCl. anything that doesn't get dissolved could be feedback-looped back in using some cleverly placed tubing.
If I may ask, what do you plan on using the acid for?

Romix - 17-9-2024 at 20:06

Quote: Originally posted by averageaussie  
Quote: Originally posted by Romix  

I thought about it, HCl fumes, doubt, all will escape boiling...
With reflux maybe possible.

You could probably use an inverted funnel placed underwater to dissolve the gaseous HCl. anything that doesn't get dissolved could be feedback-looped back in using some cleverly placed tubing.
If I may ask, what do you plan on using the acid for?

Making Potassium Chloride out of plant ash, to convert ammonium nitrate into Potassium salt.

averageaussie - 17-9-2024 at 20:06

Quote: Originally posted by Romix  
No testing papers exist for testing concentration of HOCl, even for presence I think none or there is?
There are for Chloride! I have many.
What about testing solution after bubbling lots of Cl2 into it before placing it in a sunny place and few months after, having eye on it, making sure no one adds acid to it to wind me up.

You can find HOCl test strips online pretty easy, and a pool store might also stock them. you could also but the HCl from the pool store too...

averageaussie - 17-9-2024 at 20:08

Quote: Originally posted by Romix  

Making Potassium Chloride out of plant ash, to convert ammonium nitrate into Potassium salt.

You can buy potassium chloride, it is sold as a salt substitute.

Romix - 17-9-2024 at 20:08

Quote: Originally posted by averageaussie  
Quote: Originally posted by Romix  
No testing papers exist for testing concentration of HOCl, even for presence I think none or there is?
There are for Chloride! I have many.
What about testing solution after bubbling lots of Cl2 into it before placing it in a sunny place and few months after, having eye on it, making sure no one adds acid to it to wind me up.

You can find HOCl test strips online pretty easy, and a pool store might also stock them. you could also but the HCl from the pool store too...

Where???

averageaussie - 17-9-2024 at 20:10

Quote: Originally posted by Romix  

Where???

look up "HOCl Test strips"

Romix - 17-9-2024 at 20:10

Quote: Originally posted by averageaussie  
Quote: Originally posted by Romix  

Where???

look up "HOCl Test strips"

Did on Ebay, none there...

averageaussie - 17-9-2024 at 20:11

google. type into a basic search engine "HOCl test strips"

Romix - 17-9-2024 at 20:16

Quote: Originally posted by averageaussie  
google. type into a basic search engine

Went through first page of Google search, quoting "HOCl test strips", all sites looking like scam and also very expensive, not risking it!

averageaussie - 17-9-2024 at 20:17

fair enough. you can still buy HCl from a pool store, or better yet, potassium chloride as salt substitute from a grocery store.

Romix - 17-9-2024 at 20:18

Quote: Originally posted by averageaussie  
fair enough. you can still buy HCl from a pool store, or better yet, potassium chloride as salt substitute from a grocery store.

Yes, below 10% in UK!

averageaussie - 17-9-2024 at 20:19

the HCl or potassium chloride?

Romix - 17-9-2024 at 20:20

Quote: Originally posted by averageaussie  
the HCl or potassium chloride?


HCl Dear!

averageaussie - 17-9-2024 at 20:22

the hcl being 10% will work just fine for turning the potassium salts into chlorides...

Romix - 17-9-2024 at 20:45

Quote: Originally posted by Romix  
Quote: Originally posted by averageaussie  
Quote: Originally posted by Romix  

I thought about it, HCl fumes, doubt, all will escape boiling...
With reflux maybe possible.

You could probably use an inverted funnel placed underwater to dissolve the gaseous HCl. anything that doesn't get dissolved could be feedback-looped back in using some cleverly placed tubing.
If I may ask, what do you plan on using the acid for?

Making Potassium Chloride out of plant ash, to convert ammonium nitrate into Potassium salt.



5c1a3ed0-f87d-437d-96f8-e2628ecea8c1.jpg - 10kB

averageaussie - 17-9-2024 at 20:46

electrolysis?

Romix - 17-9-2024 at 20:51

Quote: Originally posted by averageaussie  
electrolysis?

Yes, right, until Cathode bottle is filled with concentrated solution of KOH!

Romix - 17-9-2024 at 21:02

What you guys think, could this reaction be fake?
Not seen it anywhere else other than this video, although seen it's formula on other chemical forums.
You can hear guys in the video choking on Ammonia!!!
If it's fake might save me going through all the hustle on page 1, hahaha!!!
https://www.youtube.com/watch?v=CVzoQhhqfPI


[Edited on 18-9-2024 by Romix]

clearly_not_atara - 17-9-2024 at 21:43

What on Earth does that video have to do with making HCl?

You seem to be under the impression that a solution of chlorine in water is the same as the pure compound HOCl. This is not the case. An equilibrium exists, similar to the situation with carbon dioxide.

Cl2 + H2O << >> HCl + HOCl

CO2 + H2O << >> H2CO3

Only a small percentage of the chlorine exists as HOCl. Preparing pure HOCl or even an aqueous solution is very difficult.

EDIT: You may be able to make HCl from Cl2 by membrane electrolysis. PbO2 anode, chlorine in the cathode chamber, probably Ti cathode. Not sure what membrane would handle this.

It also appears that hydrogen peroxide might reduce aqueous chlorine. But IIRC it also oxidizes HCl to some extent. The resulting acid will not be free of chlorine without further work.

[Edited on 18-9-2024 by clearly_not_atara]

Romix - 17-9-2024 at 21:52

Quote: Originally posted by clearly_not_atara  
What on Earth does that video have to do with making HCl?

You seem to be under the impression that a solution of chlorine in water is the same as the pure compound HOCl. This is not the case. An equilibrium exists, similar to the situation with carbon dioxide.

Cl2 + H2O << >> HCl + HOCl

CO2 + H2O << >> H2CO3

Only a small percentage of the chlorine exists as HOCl. Preparing pure HOCl or even an aqueous solution is very difficult.

Not believing it, why there is no equilibrium with HCl alone, but would be here.
Ok maybe there is with HOCl, I did notice release of Cl2 after reacting it deep in water, could just be escaping from blowing big current of Cl2 into it and not having enough time to react with H2O or could be equilibrium, don't have enough experience with HOCl to tell!

Romix - 17-9-2024 at 23:15

Quote: Originally posted by Romix  
Quote: Originally posted by clearly_not_atara  
What on Earth does that video have to do with making HCl?

You seem to be under the impression that a solution of chlorine in water is the same as the pure compound HOCl. This is not the case. An equilibrium exists, similar to the situation with carbon dioxide.

Cl2 + H2O << >> HCl + HOCl

CO2 + H2O << >> H2CO3

Only a small percentage of the chlorine exists as HOCl. Preparing pure HOCl or even an aqueous solution is very difficult.

Not believing it, why there is no equilibrium with HCl alone, but would be here.
Ok maybe there is with HOCl, I did notice release of Cl2 after reacting it deep in water, could just be escaping from blowing big current of Cl2 into it and not having enough time to react with H2O or could be equilibrium, don't have enough experience with HOCl to tell!

There is equilibrium in close to concentrated HCl, even so HCl fumes, fumes are white, not yellow, like Cl2 should be!!!

RU_KLO - 18-9-2024 at 04:49

Early in the study of elementary chemistry one learns that chlorine reacts with water in the sense of the expression

Cl2 + H2O <<>> HCl + HOCl

and that the hypochlorous acid decomposes thus,

HClO -> HCl + O

Owing to the instability of hypochlorous acid in the presence of hydrochloric acid, the first reaction progresses to a very limited extent and the production of the end-products, oxygen and hydrochloric acid, is greatly accelerated by light. This accounts for the fact that aqueous solutions of chlorine eventually become aqueous solutions of hydrochloric acid upon standing in the laboratory, and should thecefore be protected from the light.

THE PRODUCTION OF HYDROCHLORIC ACID FROM CHLORINE AND WATER
By H. D. Gibbs

(paper on this post:
https://www.sciencemadness.org/whisper/viewthread.php?tid=16...)

The reaction between HCl and HOCl, which is the reversal of Cl2 hydrolysis,
is a textbook reaction that has long been used for water disinfection and waste-water treatment.

"Catalysis of the reaction HCl+HOCl -> H2O+Cl2 on an ice surface"
https://doi.org/10.1016/S0009-2614(99)00683-1

So from this I understand that: or the HOCl is decomposed or transformed to Chlorine.
So no HOCl & HCl living together in peace.


Romix - 18-9-2024 at 05:17

Quote: Originally posted by RU_KLO  
Early in the study of elementary chemistry one learns that chlorine reacts with water in the sense of the expression

Cl2 + H2O <<>> HCl + HOCl

and that the hypochlorous acid decomposes thus,

HClO -> HCl + O

Owing to the instability of hypochlorous acid in the presence of hydrochloric acid, the first reaction progresses to a very limited extent and the production of the end-products, oxygen and hydrochloric acid, is greatly accelerated by light. This accounts for the fact that aqueous solutions of chlorine eventually become aqueous solutions of hydrochloric acid upon standing in the laboratory, and should thecefore be protected from the light.

THE PRODUCTION OF HYDROCHLORIC ACID FROM CHLORINE AND WATER
By H. D. Gibbs

(paper on this post:
https://www.sciencemadness.org/whisper/viewthread.php?tid=16...)

The reaction between HCl and HOCl, which is the reversal of Cl2 hydrolysis,
is a textbook reaction that has long been used for water disinfection and waste-water treatment.

"Catalysis of the reaction HCl+HOCl -> H2O+Cl2 on an ice surface"
https://doi.org/10.1016/S0009-2614(99)00683-1

So from this I understand that: or the HOCl is decomposed or transformed to Chlorine.
So no HOCl & HCl living together in peace.



Thanks!

HoxonLabs - 21-9-2024 at 07:24

You could heat the solution, expose it to UV light, or reduce it with sodium thiosulphate, for example.