Sciencemadness Discussion Board

production of hydrochloric acid via 'underwater fireworks'

geffmov - 14-7-2019 at 05:17

In the synthesis of hydrogen chloride, chlorine gas and hydrogen gas when mixed and exposed to sunlight or UV light react to produce hcl(g)
I assume a DIY combustion chamber to collect the formed hcl is unworkable.
I wanted to know as i cant find any information on this, what if the hydrogen and chlorine gases was mixed and bubbled through a solution of water/hydrochloric acid while been exposed to strong UV light?
I was wondering if theyd still react and form hcl underwater, once the solutions saturated the water would be fuming hydrochloric acid and changed?

The nearest reaction i could find is acetylene and chlorine 'underwater fireworks'
https://youtu.be/1Y5aCSOSQgU

Im looking for a total synthesis for either hydrochloric acid ( which i dont think there is whats practical) WITHOUT needing sulfuric acid,
Or a synthesis of sulfuric acid what doesnt consume hydrochloric acid, as with plenty of sulfuric acid getting hydrochloric acid is easy.
many thanks

XeonTheMGPony - 14-7-2019 at 06:00

My very first throw at making a chemical plant was a chloro-alkalie cell, at the time I needed sodium hydroxide, but what to do with the H2 and Cl2? well I learned they'd burn to make HCl.

So using a very big jar, some check valves and larg needles (16gauge) and a bbq sparker I set off. drilled the bottom to put the needles in, hooked up the bbq sparker and lead the exhaust into a 5g bucket of tap water. Much to the amusement of adults it worked.

So you can simply burn it to make HCl, and generate sodium hydroxide while at it.

the design did eventually grow to a much safer and fine tunable system, but at the core it was the same thing as described.

Just do not smell the tube to see if it is working!

rockyit98 - 14-7-2019 at 06:10

You dont have to mix H2 and Cl2
Cl2 + H2O <------> HCl + HOCl
but under UV light
Cl2(aq) + H2O ---(UV)---> HCl(aq) + O2(g)
this prevent explosions

Ubya - 14-7-2019 at 06:18

Quote: Originally posted by rockyit98  

but under UV light
Cl2(aq) + H2O ---(UV)---> HCl(aq) + O2(g)
this prevent explosions


any reference for that?

wg48temp9 - 14-7-2019 at 07:39

The OP should look at this video of hydrogen burning in chlorine.:

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

or and search using "hydrogen burning in chlorine"

AJKOER - 14-7-2019 at 08:25

Per a prior comment:
Quote: Originally posted by AJKOER  
...............

2 HOCl --CuO--> 2 HCl + O2

3 HOCl --CuO--> 2 HCl + HClO3

Source: "Enhanced Bromate Formation during Chlorination of Bromide Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid" by Chao Liu, Urs von Gunten, and Jean-Philippe Croue, Equations (9) and (10), available at https://infoscience.epfl.ch/record/182097/files/es3021793.pd... .


where I would rapidly remove the CuO presence from the starting cold hypochlorous acid to limit cupric creation.

With respect to the required cupric oxide, a path to CuO per one of my prior threads at https://www.sciencemadness.org/whisper/viewthread.php?tid=84... .

Also, a path to HOCl from the action of CO2 gas (from say vinegar acting on baking soda) acting on a mix of chlorine bleach (say 6% NaOCl) and DampRid (dry CaCl2) via the reactions:

CaCl2 + 2 NaOCl <--> Ca(OCl)2 + 2 NaCl

H2CO3 + Ca(OCl)2 --> CaCO3 (s) + 2 HOCl

Distilling half the mix, due to the volatile nature of the hypochlorous acid, brings over largely all the HOCl/Cl2O, so 6% is now around 10% HOCl. Source, see Watts' Dictionary of Chemistry, Volume 2, page 16, the concentration of Hypochlorous Acid on a single distillation can be nearly doubled, to quote from Watts:

"A dilute solution of HClO may be distilled with partial decomposition, the distillate is richer in HClO; Gay-Lussao found that, on distilling a dilute solution to one-half, the distillate contained five-sixths of the total HClO (C. R. 14, 927)"

Repeat again to further concentrate but do not (for safety reasons relating to decomposition) bring the concentration of hypochlorous acid over say 20%.

Note, as requested, no employment of any strong acid to create an acid, and interestingly, the presence of the divalent salt CuCl2 in the acid mix, actually increases the activity coefficient of the acid solution!
-----------------------------

Burning H2 in Cl2 is an actual commercial process to very high purity HCl. However, for most it is an expensive and problematic path.
------------------------------

If you view any of the online videos on the explosion of H2/Cl2 mixtures, it should be apparent that it is far too energetic path to HCl.

[Edited on 14-7-2019 by AJKOER]

rockyit98 - 14-7-2019 at 22:21

Quote: Originally posted by Ubya  
Quote: Originally posted by rockyit98  

but under UV light
Cl2(aq) + H2O ---(UV)---> HCl(aq) + O2(g)
this prevent explosions


any reference for that?



https://www.quora.com/How-does-chlorine-react-with-water

http://www.sciencemadness.org/talk/viewthread.php?tid=13828

geffmov - 20-7-2019 at 03:47

Thankyou very much all for the replies. I didnt know the hydrogen flame could simply burn in the chlorine, i thought it detonated.
The safety issue about the flame, to keep it reliably lit do you think a mantle like out of a tilly lamp can be employed as a burner? or would whats in a tilly mantle negatively react causing sidereactions.
Employing something like a mantle if it worked would give much more stable control over how fast the gases was fed through. I think initially the mantle contains metal oxides which may get burnt off once the mantles in place and first used.

"The mantles are a ceramic mesh that encase the flame produced by the lantern. Typical mantles look like this: Mantles start out as silk fabric sacks impregnated with different oxides. The standard for decades has been the Welsbach mantle, which uses a mixture of thorium oxide, cerium oxide and magnesium oxide."

If mantles could be used thered be so much more control over production and still keep the apparatus compact.

I have followed up other suggestions made too, its just i was going to make a chloroalkali cell anyway so the byproducts if i could make hydrochloric acid this way would be the most convenient.

Im also looking into suitable diaphragms and membranes for chloroalkali cell. Ive come across some teflon membranes very cheap are these suitable for such a cell? https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.eb...

Also would they be suitable in electrolysis cells to keep anode/cathode free of slimes from each other?

Im not sure if the fact theyre 'hydrophobic' actually becomes a barrier for ion exchange.


[Edited on 21-7-2019 by geffmov]

geffmov - 25-7-2019 at 05:44

Quote: Originally posted by XeonTheMGPony  
My very first throw at making a chemical plant was a chloro-alkalie cell, at the time I needed sodium hydroxide, but what to do with the H2 and Cl2? well I learned they'd burn to make HCl.

So using a very big jar, some check valves and larg needles (16gauge) and a bbq sparker I set off. drilled the bottom to put the needles in, hooked up the bbq sparker and lead the exhaust into a 5g bucket of tap water. Much to the amusement of adults it worked.

So you can simply burn it to make HCl, and generate sodium hydroxide while at it.

the design did eventually grow to a much safer and fine tunable system, but at the core it was the same thing as described.

Just do not smell the tube to see if it is working!



I would be immensely grateful if you would share more details of your later experimentation and setup?

In particular your chlorine chamber with hydrogen flame.
Id like to build a cell capable of producing say a couple of kg per day of 36% hydrochloric acid, or more.
Im not sure yet in my imagination what a practical build would be. Sometimes i overcomplicate things.

Im trying to visualise the combustion chamber. I am assuming it must really be either borosilicate or graphite due to nature of the reagents, and heat generated in the reaction . The example industrially i saw was graphite.

Possibility of chlorine detonation by light leads me away from using glass... but Ive the thought of a large 10-15l rbf upturned, partially filled with constantly pumped water to catch the hcl and dissapate heat as the gases then run through a bubbler system.
Running the hydrogen and chlorine inside isnt problematic in itself.
Ive not yet looked into a reliable spark source.

My other thought was a graphite crucible one used in furnaces, upturned and sealed by been sat in water. Even possibly totally immersed in water in a large bucket 20l lid sealed on with a bubbler to allow waste gas escape, or in the case of chlorine il bubble it through naoh, naocl always comes in handy as a chlorinator.
I cant find any DIY examples online to go from, usually theres a selection and its possible to select and build upon others great ideas. This ones very vague.

And id love to know about the diaphragm/membrane i mentioned in previous comment if itd be suitable for the chloroalkali cell.
If members know of good literature in electrolysis cells, different builds and types of cell, particularly chloroalkali, sulfuric acid regeneration-production please point the way, this isnt my usual area but i learn fast.

thanks a lot guys for the replies, this is something i am in process of gathering materials to build