Sciencemadness Discussion Board - Make Sodium Hypochlorite from Calcium Hypochlorite?

Make Sodium Hypochlorite from Calcium Hypochlorite?

LuckyWinner - 28-10-2020 at 09:32

I saw a youtube video

Make concentrated sodium hypochlorite (bleach)
https://youtu.be/rMcmJeckZoI

10g sodium carbonate 105.988 g/mol, 0.094mol
48ml distilled water 18.02 g/mol , 2.66 mol
14g calcium hypochlorite powder 142.98 g/mol, 0.098mol

(user added a sightly mol excess of calcium hypochlorite,
Sodium Hypochlorite 73.953537 g/mol x 0.094mol = 6.951g of product generated
which is dissolved in 48ml of water.
this will result in a 14.48% Sodium Hypochlorite water solution.

!! ANY MISTAKES WITH THIS CALCULATION?

Procedure:
Mix sodium carbonate under mag stirring into the distilled water,
then cool this mixture in an ice bath and add calcium hypochlorite.
Keep the temperature below 10C to avoid decomposition of the product.
Mix this for 20 minutes, then filter out the calcium carbonate.
The Filtrate is placed inside the freezer to precipitate any left over calcium carbonate.
Leave overnight and vacuum filter it again.
You will have a sodium hypochlorite solution now in 48ml of water.
Store this under 5C to avoid decomposition.

Now this patent here says,
https://patents.google.com/patent/US2506630A/en

Quote:

...

may be prepared by adding calcium hypochlorite to a hot aqueous solution containing considerable excess alkali carbonate over that required to convert all the calcium to calcium carbonate and separating the latter from the dissolved alkali hypochlorite. The amount of excess carbonate is not very critical but it should be suflicient to leave un-ionised alkali carbonate in the solution.

I have found that contrary to expectation, heatin the solution as above described does not cause any appreciable degradation of the hypochlorite and under the conditions set out above an almost completely stable solution of sodium hypochlorite is obtained.

Conveniently the alkali carbonate solution may be at or near boiling point before addin the calcium hypochlorite, preferably at between 180 and 212 F. By this means the calcium carbonate is rapidly formed to completion and an easily filtrable precipitate is obtained.

The presence of an electrolyte further assists the complete removal of the calcium carbonate and as some sodium chloride will be formed and does not interfere with the subsequent use of the hypochlorite liquor, the addition of sodium chloride either simultaneously with or subsequently to the addition of the calcium hypochlorite is advisable.

The employment of the alkali carbonate in the form of bicarbonate will produce an evolution of carbon dioxide which will automatically agitate the liquor durin precipitation and ensure that no alkali hydroxide is present.
...

suggested
water -----------------------------...-- 100
Sodium bicarbonate -------------------- 10
Sodium carbonate ---------------------- 30
Borax -------------------------------- 2
Magnesium carbonate ------------------ 2%
Sodium chloride --------------------...--- 2%
Calcium hypochlorite ------------------- 5
Citric acid -----------------------------
Calcium chloride ----------------------- 2 4.
Calcium phosphate ------------------

...
contrary to previous experience which has shown that heat causes degradation of hypo chlorite solutions, the calcium hypochlorite is then added and the mixture is allowed to cool whilst being continually stirred and after the solution is cool the sodium chloride is added. This causes the rapid sedimentation of the bye products present in the solution and thus pre vents all chance of the hypochlorite Solution be ing degraded by t

to sum this up. I dont want to add all these compounds.

the easiest way to make Sodium Hypochlorite from Calcium Hypochlorite
is to do it like in the video?

Sodium Hypochlorite will not degrade under heat if you add sodium chloride
after it has been added to hot Calcium Hypochlorite in water?
(without all the other ingredients)

Any other errors?

I want to use this 14.48% Sodium Hypochlorite Solution to make Chloroform.
Using straight Calcium Hypochlorite seems to be a MESS, according to other members here.

usual Chloroform yield supposedly is ~70% on Sodium Hypochlorite.
that means in the above example, Sodium Hypochlorite, will yield
0.094mol x 70% = 0.0658 mol of chloroform which has a 119.37 g/mol = 7.87g weight.
chloroform density 1.49 g/cm³ / 7.87g = 5.28ml yield.

[Edited on 28-10-2020 by LuckyWinner]

karlos³ - 28-10-2020 at 20:27

Read under 2. notes, point 1. here: http://www.orgsyn.org/demo.aspx?prep=CV2P0428

B(a)P - 28-10-2020 at 21:05

I presume you have exhausted all possible options for obtaining NaClO? Liquid pool chlorine from a hardware store or pool shop?
In my experience the calcium carbonate is a massive pain to filter out.

teodor - 29-10-2020 at 02:22

For the purpose of unwanted Fe ions precipitation from salts (e.g., Zn) I often use this solution (at room temperature):

1g Ca(OCl)2 + 1g Na2CO3 + 100ml H2O

The filtration is very easy, I didn't remember any problems with just a "fast" filter paper. I use Ca(OCl)2 marked as 70% of chlorine.

It is strange that you can't use Ca(OCl)2 for the haloform reaction directly.

[Edited on 29-10-2020 by teodor]

karlos³ - 29-10-2020 at 03:23

Quote: Originally posted by teodor

It is strange that you can't use Ca(OCl)2 for the haloform reaction directly.

You can, but either in a heavy dilution, or with other unpleasant results.

I used to make chloroform via Ca(OCl)2, 100g, 800ml in a 2l flask with a large 70 or 80 stirbar(bordering hard what is possible and requiring strict control).
It foams and is VERY exothermic, but if you start dropping the acetone really, really slow in at first, you can actually use the resulting exothermia to distill the chloroform over as it forms.
If you don't put enough attention to it, it will probably foam over and gets too hot to be touched, could hardly just dump the flask into a bucket of water.

In other cases with a reactant that is not so well soluble in water like acetone, see the orgsyn preparation for example, you have two such badly soluble substances in there, and what will you even do then, run the reaction in 10, maybe 15l of water?
Its just really inconvenient due to its solubility, but it works nonetheless, its just proceeds quite different to the normal haloform.

LuckyWinner - 2-11-2020 at 10:10

quote from
http://www.orgsyn.org/demo.aspx?prep=CV2P0428

Quote:

In a 3-l. round-bottomed flask 250 g. of commercial calcium hypochlorite is dissolved in 1 l. of warm water, and a warm solution of 175 g. of potassium carbonate and 50 g. of potassium hydroxide in 500 cc. of water is added. The flask is stoppered and shaken vigorously until the semi-solid gel which first forms becomes quite fluid. The suspended solid is removed by filtration on a large Büchner funnel, washed with 200 cc. of water, and sucked as dry as possible with the aid of a rubber dam and an efficient suction pump. The filtrate of approximately 1.5 l. is placed in a 3-l. round-bottomed flask and is ready for the addition of methyl β-naphthyl ketone.
Such a solution contains approximately 200 g. (2.3 moles) of potassium hypochlorite. Sodium or potassium hypochlorite may be used, but the calcium salt is not satisfactory because the calcium salt of β-naphthoic acid is sparingly soluble.

250g calcium hypochlorite (60%)
1 l. of warm water
175 g. of potassium carbonate K₂CO₃ and
50 g. of potassium hydroxide KOH in
500 cc. of water

to make 200 g. (2.3 moles) Potassium hypochlorite KClO
in 1.5L of water

you say you need
25 liters of water for the same amount of calcium hypochlorite as quoted above?
according to your calculation with sodium carbonate.

why?

Quote: Originally posted by teodor

For the purpose of unwanted Fe ions precipitation from salts (e.g., Zn) I often use this solution (at room temperature):

1g Ca(OCl)2 + 1g Na2CO3 + 100ml H2O

The filtration is very easy, I didn't remember any problems with just a "fast" filter paper. I use Ca(OCl)2 marked as 70% of chlorine.

It is strange that you can't use Ca(OCl)2 for the haloform reaction directly.

[Edited on 29-10-2020 by teodor]

[Edited on 2-11-2020 by LuckyWinner]

LuckyWinner - 10-11-2020 at 07:41

what ratio to use when trying to make sodium hypochlorite
with sodium carbonate / bicarbonate?

10g sodium carbonate 105.988 g/mol, 0.094mol
48ml distilled water 18.02 g/mol , 2.66 mol
14g calcium hypochlorite powder 142.98 g/mol, 0.098mol

(user added a sightly mol excess of calcium hypochlorite,
Sodium Hypochlorite 73.953537 g/mol x 0.094mol = 6.951g of product generated
which is dissolved in 48ml of water.
this will result in a 14.48% Sodium Hypochlorite water solution.

this calculation is correct?

TheMrbunGee - 10-11-2020 at 08:20

Quote: Originally posted by LuckyWinner

what ratio to use when trying to make sodium hypochlorite
with sodium carbonate / bicarbonate?

10g sodium carbonate 105.988 g/mol, 0.094mol
48ml distilled water 18.02 g/mol , 2.66 mol
14g calcium hypochlorite powder 142.98 g/mol, 0.098mol

(user added a sightly mol excess of calcium hypochlorite,
Sodium Hypochlorite 73.953537 g/mol x 0.094mol = 6.951g of product generated
which is dissolved in 48ml of water.
this will result in a 14.48% Sodium Hypochlorite water solution.

this calculation is correct?

Here You can get the amounts. there are 2 groups of ClO at Calcium, so You'll get double the amount of NaClO You calculated.

[Edited on 10-11-2020 by TheMrbunGee]

LuckyWinner - 10-11-2020 at 09:44

Quote: Originally posted by TheMrbunGee

Quote: Originally posted by LuckyWinner

Here You can get the amounts. there are 2 groups of ClO at Calcium, so You'll get double the amount of NaClO You calculated.

[Edited on 10-11-2020 by TheMrbunGee]

thanks!
that calculator is great.

that means
0.1958277 moles of NaClO 14g is generated, IF PURE
100% calcium hypochlorite is used.

I FORGOT, the pool calcium hypochlorite is usually at 60 to 70% concentration that means.
it will be ~9.5g NaClO yield.
which results in ~20 to 21% concentrated bleach if you follow the video.

this concentration can safely be used to make chloroform?
since high concentrations decompose fast and form chlorine gas, no?
video says just keep it under 10C.

[Edited on 10-11-2020 by LuckyWinner]

[Edited on 10-11-2020 by LuckyWinner]

woelen - 11-11-2020 at 00:21

Pool calcium hypochlorite is not 60-70% calcium hypochlorite dihydrate, but it is 60-70% so-called active chlorine! That is a totally different concept.

Active chlorine is defined as the mass of elemental chlorine, produced by adding an excess amount of HCl, divided by the mass of the chlorinator product or bleach product.

So, 100 grams of swimming pool calcium hypochlorite dihydrate produces between 60 and 70 grams of elemental chlorine, when treated with excess HCl.

As an example, I take my Blueline pool chlorinator. This is labeled as at least 68% active chlorine.

So, 100 grams of this produces at least 68 grams of Cl2, when treated with excess hydrochloric acid.

The commercial form of calcium hypochlorite is the dihydrate, so the reaction with excess acid is:
Ca(OCl)2.2H2O + 4 HCl -> CaCl2 + 4 H2O + 2 Cl2

So, for making 1 mole of Cl2, half a mole of Ca(OCl)2.2H2O is used. For 68 grams of Cl2, this means that 85.8 grams of Ca(OCl)2.2H2O is used.

So, my product is appr. 86% pure. The remainder most likely will be Ca(OH)2, CaCl2, CaCO3. The stuff I have does not give clear solutions.

-------------------------------------------------------------------------

Some compounds even can have more than 100% active chlorine! In some countries, lithium hypochlorite is available as bleach in solid form. This stuff, if pure, has an active chlorine content of more than 100%.

For TCCA, the 100% pure product has an active chlorine content of appr. 92%.

[Edited on 11-11-20 by woelen]

TriiodideFrog - 11-11-2020 at 01:06

Just do electrolysis on some sodium chloride solution.

You will need two inert containers such as glass or porcelain, a battery, salt, rag or cloth and water.

Place a wire from the battery's positive side into one of the containers and another wire or other conductor into the other container. Fill each container with saltwater. Seawater can also be used. The soaked rag should be draped over the side of each container and will provide a pathway for the electricity to flow.

Chlorine will form from the anode side (positive side) and produce sodium chlorate in that container. The cathode (negative side) will bubble hydrogen gas and form pure sodium hydroxide.

When the reaction is complete no more bubbles will form and you'll have a jar of homemade bleach (sodium chlorate) and homemade oven cleaner (sodium hydroxide, or commonly called lye) in the other.

macckone - 11-11-2020 at 07:31

20% can be used but you want to keep it on ice and slowly add the acetone.
Once the initial reaction starts and it starts warming up you want to stop and let it subside before proceeding.
After that you can add it faster and as long as it is kept cold you are good.
If it warms up too fast it gets violent.

Here is a video of hot reacting and distilling chloroform from calcium hypochlorite.
https://www.youtube.com/watch?v=heqMdYqqMGs

They use a fast add and distill instead of cooling.
They use a relatively small amount of reactants for a 500ml flask to avoid boil over.
This is closer to the commercial process.
They used to much acetone but the basic idea is used commercially.
They distill off the acetone and chloroform then use weak sodium hydroxide to neutralize any acid and calcium chloride to dry then distill a second time.

I use a cold method but let the slurry settle which is surprisingly fast, decant, and a second quantity of water and repeat.
Not everything dissolves or settles so it is cloudy but it works much better than just dumping everything together.
I add a small amount of calcium chloride to the mix.
Then do the addition over ice.

Work up can be either separation or distillation.

LuckyWinner - 12-11-2020 at 03:29

now im confused.

what concentration % of sodium hypochlorite solution will this generate?

the youtube video shows these:

10g sodium carbonate 105.988 g/mol, 0.094mol
48ml distilled water 18.02 g/mol , 2.66 mol
14g calcium hypochlorite powder 142.98 g/mol, 0.098mol

it should produce
sodium hypochlorite 14.6g
calcium carbonate 9.8g

in 48ml water thats 30.4% sodium hypochlorite solution???

that means I need to use a total of 70ml water in total to get a
20.8% sodium hypochlorite solution?