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Author: Subject: Evaporating bleach - what would come out?
Draeger
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[*] posted on 25-4-2020 at 13:24
Evaporating bleach - what would come out?


So, I know that boiling bleach produces sodium chlorate, but what comes out from gently evaporating the bleach at room temperature?

I'm not really sure if the disproportionation of the sodium hypochlorite needs heat or just happens on the evaporation of water anyway.




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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S.C. Wack
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[*] posted on 25-4-2020 at 14:18


Smell hypochlorite as liquid or solid...it's Cl that's coming out, yes? Whether this is the result of inherent instability or CO2 is not important...time is not on your side and neither is exposure to air. BTW the bleach already has chloride and chlorate in it.

[Edited on 25-4-2020 by S.C. Wack]




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AJKOER
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[*] posted on 25-4-2020 at 14:24


To create chlorate, you have to add some energy in the form of heat or light. A source of hydroxyl radicals is also good in the presence of HOCl.

Something I may be able to try is first prepare Mg(OCl)2 from adding NaOCl in excess to MgSO4 (Epsom's Salt). Freeze out the Na2SO4.7H2O, leaving magnesium hypochlorite. Add a small amount of Aluminum foil, a piece of high surface-area carbon, and finally some vinegar. This creates a bleach battery based on OCl-/HOCl with anodic Al and a noble cathode, where the electrons generated in the battery cell stay in the solution and can interact with pumped in O2. Warm the solution to over 60 C and try not to boil (reduces chlorate yield).

Reaction logic: Battery cell has solvated electrons, e-(aq). Then, in the presence of supplied oxygen:

e- (aq) + O2 = *O2- (the superoxide radical anion)

OCl- + H+ = HOCl (hypochlorous acid from the action of a weak acid on hypochlorite)

*O2- + HOCl-> .OH + Cl- + O2 (the source of hydroxyl radicals)

Why Magnesium hypochlorite? Because it is reportedly oxygen-sensitive creating chlorates on warming. The chemistry of Mg++ parallels Al3+ and Ca2+ in forming a weak mixed salt with superoxide (see discussion and references at https://www.sciencemadness.org/whisper/viewthread.php?tid=96... ), which extends the effective longevity/reactivity of the superoxide radical.

Supporting basis, my prior comments on SM at https://www.sciencemadness.org/whisper/viewthread.php?tid=15... to quote:

"Apparently, burnt vegetables in contact with air and food acids can convert chlorine bleach to ClO3- (in place of IO3- here) and boom, as I noted previously on SM:

"Carbon produced by accidentally burning vegetables is also a source of radicals especially in a pan (of Al or Fe?) with boiling bleach. In fact, there is a report in Bretherick on an explosion occurring by someone trying to clean a pot with burnt vegetables on boiling with NaOCl, and forgetting it was on the stove! An accidentally revealed chlorate route!"

Also, some interesting comments from this patent https://patents.google.com/patentUS4380533A/en) which focuses on making Mg(OCl)2 absence chlorate, but, to quote:

"High rates of addition and high rates of reaction are desired so that chlorine gas is rapidly evolved from the reaction mixture. This enables the evolved chlorine to be recovered and, for example, recycled to the calcium hypochlorite process. At low rates of addition and subsequently low reaction rates such as those employed in a process in which the reactants are in solution, the chlorine is evolved slowly and considerable amounts of chlorate ion are formed in the solution. For example, generally about 25 percent or more of the available chlorine in the solution is converted."

So, my acidification of the hypochlorite leads to HOCl. Relatedly, free Cl2 in solutions that is not released as gas, also produces HOCl, a likely precursor to chlorate.

Also, per this patent https://patents.google.com/patent/EP0498484B1/en to quote:

"In the cyclic chlorate process the pH is regulated in several positions within the range 5.5 - 12, to optimize the process conditions in each unit operation."

where a pH above 4.88 is consistent, with superoxide creation and not acidic *HO2 (perhydroxyl radical).

[Edited on 25-4-2020 by AJKOER]

[Edited on 25-4-2020 by AJKOER]
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Draeger
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[*] posted on 25-4-2020 at 14:33


Quote: Originally posted by S.C. Wack  
Smell hypochlorite as liquid or solid...it's Cl that's coming out, yes? Whether this is the result of inherent instability or CO2 is not important...time is not on your side and neither is exposure to air. BTW the bleach already has chloride and chlorate in it.

[Edited on 25-4-2020 by S.C. Wack]

Ah. Thank you. Short side question: does boiling bleach generate dangerous amounts of chlorine? I'm suspecting it does, but if so that means I can't do it, so I'd like to check.




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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S.C. Wack
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[*] posted on 25-4-2020 at 14:43


Quote: Originally posted by AJKOER  
To create chlorate, you have to add some energy in the form of heat or light.


Anything above freezing is heat.

Quote: Originally posted by AJKOER  
Why Magnesium hypochlorite? Because it is reportedly oxygen-sensitive creating chlorates on warming.


They all form chlorates...Mg is preferred because it gives the best isolated yield of KClO3 from the theoretical amount of KCl and chlorate.




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S.C. Wack
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[*] posted on 25-4-2020 at 14:54


Quote: Originally posted by Draeger  
does boiling bleach generate dangerous amounts of chlorine?


Try it in a test tube. I doubt it but can't speak for all products. I would think the rate of loss is lessened by the atmosphere of water.




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Draeger
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[*] posted on 25-4-2020 at 16:19


Quote: Originally posted by S.C. Wack  
Quote: Originally posted by Draeger  
does boiling bleach generate dangerous amounts of chlorine?


Try it in a test tube. I doubt it but can't speak for all products. I would think the rate of loss is lessened by the atmosphere of water.

Would boiling just a little amount of bleach in a normal beaker work as a test? I don't have any glass test tubes, sadly.




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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draculic acid69
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[*] posted on 25-4-2020 at 21:07


Quote: Originally posted by Draeger  
Quote: Originally posted by S.C. Wack  
Quote: Originally posted by Draeger  
does boiling bleach generate dangerous amounts of chlorine?


Try it in a test tube. I doubt it but can't speak for all products. I would think the rate of loss is lessened by the atmosphere of water.

Would boiling just a little amount of bleach in a normal beaker work as a test? I don't have any glass test tubes, sadly.


Order a few off eBay they only cost a few dollars delivered.a glass cigar tube could also be used.
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[*] posted on 26-4-2020 at 04:06


There are two competing reactions for hypochlorite:
2ClO->2Cl-+O2
3ClO->2Cl-+ClO3-
Both are effectively irreversible. Both should be promoted by higher temperature but also higher concentration of hypochlorite. So which conditions favour which?
Hypochlorite solutions can exist at temperatures below freezing, too. Not its own, but solutes lower water freezing point. Instead of evaporation, you could concentrate bleach by freezing and skimming off pure ice as it floats to top... which still would increase the concentration and thereby promote decay.
At low temperatures, sodium hypochlorite precipitates from saturated solutions as NaClO*5H2O.
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Draeger
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[*] posted on 26-4-2020 at 06:24


Quote: Originally posted by draculic acid69  
Quote: Originally posted by Draeger  
Quote: Originally posted by S.C. Wack  
Quote: Originally posted by Draeger  
does boiling bleach generate dangerous amounts of chlorine?


Try it in a test tube. I doubt it but can't speak for all products. I would think the rate of loss is lessened by the atmosphere of water.

Would boiling just a little amount of bleach in a normal beaker work as a test? I don't have any glass test tubes, sadly.


Order a few off eBay they only cost a few dollars delivered.a glass cigar tube could also be used.

And how do I heat the test tube?

Quote: Originally posted by chornedsnorkack  
There are two competing reactions for hypochlorite:
2ClO->2Cl-+O2
3ClO->2Cl-+ClO3-
Both are effectively irreversible. Both should be promoted by higher temperature but also higher concentration of hypochlorite. So which conditions favour which?
Hypochlorite solutions can exist at temperatures below freezing, too. Not its own, but solutes lower water freezing point. Instead of evaporation, you could concentrate bleach by freezing and skimming off pure ice as it floats to top... which still would increase the concentration and thereby promote decay.
At low temperatures, sodium hypochlorite precipitates from saturated solutions as NaClO*5H2O.

Wouldn't that be risky, since solid NaClO is very unstable, and if it precipitated shock could set it off?




Collected elements:
Al, Cu, Ga, C (coal), S, Zn

Collected compounds:

Inorganic:
NaOH; NaHCO3; MnCl2; MnCO3; CuSO4; FeSO4; aq. 30-33% HCl; aq. NaClO; aq. 9,5% ammonia; aq. 94-96% H2SO4; aq. 3% H2O2

Organic:
citric acid, sodium acetate, sodium citrate, petroleum
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unionised
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[*] posted on 26-4-2020 at 09:57


If you dry bleach there's a fair to middling chance that you will get salt.
Bleach slowly evolves oxygen.(It's rather faster if you add a cobalt catalyst)
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[*] posted on 26-4-2020 at 12:33


The Cl you smell is hypochlorous acid from CO2 and hypochlorite, which also oxidizes hypochlorite while neutralizing alkalinity, further encouraging chlorate.



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[*] posted on 27-7-2020 at 08:47


I did this very thing last summer. Unionised is right. The crystals left behind from evaporating common bleach were pure salt. I tasted it. Just salt with a very faint hint of bleach smell. I’d read somewhere that that was what would happen. I just had to try it.



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[*] posted on 27-7-2020 at 09:06


It is not pure salt, it is a mixture of sodium chloride and chlorate, depending on the pH one of the two will predominate.
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[*] posted on 27-7-2020 at 09:44


Sorry for the OT, but the smell of hypochlorite, isn't that hypochlorous acid and not chlorine?
I know that chlorine does not smell like hypochlorite salts.
And that the "public pool smell", which is the same as hypochlorite salts, must come from hypochlorous acid too(unlike the public opinion which says it is the reaction of urine with chlorine:o).
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