MrMario
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Concentrated NaClO sol. from Ca(ClO)2
I'm wondering if anyone has experience in making a sodium hypochlorite solution from Calcium Hypochlorite tabs/powder (>65%).
The main reason is that the calcium hypochlorite is not completely pure (some Ca(OH)2 and other stabilizing agents/byproducts).
What would be my best option? I was thinking about a replacement reaction with Na2SO4, so that CaSO4 falls out solution or would creating chlorine gas
from it and bubbeling through NaOH solution be a better option?
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Tdep
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Yes I have made it, you can see me doing it here for my video on hydrazine sulfate. I used Na2CO3 in the video, but i've also tried with Na2SO4
and it's worked equally well, just depends what byproduct you want in your reaction.
If you have a vacuum filtering system, that would be my way of doing it. Forget the displacement if you can only gravity filter things. In that case,
the chlorine generator will work.
Oh and never try the displacement using equal molar NaOH. The whole solution just sets into a jelly-like mass, it's terrifying.
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blogfast25
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So what was the estimated final concentration of NaClO?
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Daffodile
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In the video it looks like he has half a litre, ish, of solution? So m best guess for concentration is about 1.5 M, about twice the concentration of
household bleach.
I'm more likely to be wrong than right though cuz my math sucks, so keep that in mind.
EDIT: Slightly unrelated, I really wouldn't recommend the chlorine generator method. In some reactions like making Chloropicrin or Chloroform, the
Hydroxide can kinda mess with it a bit (or a lot).
[Edited on 25-3-2016 by Daffodile]
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MrMario
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57,3g of NaClO is created in lets say ~500ml and is indeed 1.54M 
Another question, if i want to make 15% NaClO solution, is that by weight or volume? Like 15g of NaClO in 100mls of water?
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MrMario
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I attempted to make a concentrated Sodium Hypochlorite solution with Calcium Hypochlorite but found that it decompose pretty quickly at 20% into
chlorine gas.
In 250ml of H2O I added 48g of Ca(ClO)2 = 0,34mol and 0,34mol of Na2CO3. The CaCO3 falls out of solution and NaClO stays in solution. I noticed that
the solution starts to decompose at +5C with some strong smell of chlorine.
My question is if it is smart to use vacuum filtration to filter the CaCO3 off. Since vacuum distillation lets liquids boil at a lower pressure
wouldn't this also accelerate the decomposition of NaClO a lot during filtration? It takes a while to filter and the solution also cannot be cooled
during this step. I don't know if decomposition is accelerated for sure, so does anyone know?
Maybe I can prevent this to store the mixture in a closed bottle in a cold fridge and then decant it?
Nowadays consumer bleach has really low concentrations and you pay a lot for transport of water, so it would be nice to see a good method to make
concentrated hypochlorite bleach.
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AvBaeyer
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You will find some useful information on the preparation of sodium and potassium hypochlorite in Organic Syntheses, Col. Vol. 2, page 428 (see Notes 1
and 2). You can find this reference online.
AvB
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Mateo_swe
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Thanks for that, it contains relevant info.
Organic Syntheses, Coll. Vol. 2, p.428 (1943) - β-NAPHTHOIC ACID
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