Make Potassium Chlorate: Guide & Tips

[‡brandon]

Hi another annoying question from me. I found this walkthrough on how to make potassium chlorate while reading through some things.
http://img92.imageshack.us/img92/999/adsfpj5.png [Broken]
Think this way will work? It seems like it should work when you think about it, but that's not really what I am asking for. How long do you think it will take to do this? Or how would you know its done? Theres also the crystalization method using bleach and potassium chloride. But I wasnt sure on it too much. Incase you don't know what it is ill post at the bottom. It seems that method using electrolsys should work. Is the way using bleach better, or worse? Does anyone have any other suggestions? I am curious to know just to experiment with. And:

Take one gallon of bleach, place it in the container, and begin heating it. While this solution heats, weigh out 63 grams of potassium chloride and add this to the bleach being heated. Constantly check the solution being heated with the hydrometer, and boil until you get a reading of 1.3. If using a battery hydrometer, boil until you read a FULL charge.

Take the solution and allow it to cool in a refrigerator until it is between room temperature and 0 degrees Celcius. Filter out the crystals that have formed and save them. Boil this solution again and cool as before. Filter and save the crystals.

Take the crystals that have been saved, and mix them with distilled water in the following proportions: 56 grams per 100 milliliters distilled water. Heat this solution until it boils and allow to cool. Filter the solution and save the crystals that form upon cooling. This process of purification is called "fractional crystalization". These crystals should be relatively pure potassium chlorate.

And sorry for all the questions :p
Im just curious.

 

[mrjeffy321]

I am quite familiar and experienced with both of these procedures (as I am sure you already know).

Think this way will work? [...] How long do you think it will take to do this? Or how would you know its done?

Yes, the electrolytic method will work, but there are better sets of [electrolytic] instructions out there that I would recommend over the link you have above.
The ___ Chloride will be converted into ____ Chlorate, which can then be extracted from solution, dried, and used as you see fit.

The length of time one would need to perform the electrolysis on the Chloride solution depends on the current through the electrolytic cell (higher current means faster production). Depending on your level of sophistication and budget, you can keep track of how far along in the conversion process you are by keeping track of the total charge which has been put through the cell. A simply way to do it is to assume a constant current of ___ amps and keep it running for ____ hours. After this period of time, ____ amp hours of charge will have flowed through the cell and (theoretically) have converted ____ moles of Cl- to ClO3-.

Theres also the crystalization method using bleach and potassium chloride. [...] Is the way using bleach better, or worse?

Would you care to define "Better" and "Worse" in this situation?
Both methods will work. One method (the NaOCl decomposition) will yield quicker results than the other (electrolysis). One method is considerably cheaper depending on the quantity you wish to produce (electrolysis for larger quantities).

 

[‡brandon]

But the bleach method works decently and makes really decent batch of potassium chlorate? When I did it before it was turning brown.. Meaning it wasnt too pure. So I thought this method would be better. It might help if you fill in the current and the amount made blanks :p
But what one would you recommend? I can always make more batches of the potassium chlorate using bleach, so that's not really a factor. I am looking for a method that will show results, and not something I have to make a guess about (like the electrolsys method). So now I am wondering how do you tell when its done? I just did a quick amount. And let it sit for probly not even an hour. It was a small amount though. Was in a small glass, and the chloride was probly 1/8th filled of the glass. Exacts arnt really need I think atm, just get a glass and you should be able to make an educated guess. But basically not much.
And for the bleach method, is the turning brown alright? Because I might try it again. Last time I did that it was like a while back. I've gained a bit more experience since then though, so maybe it will be better. Lastly, how do you exactly tell if its potassium chlorate? I know by looks you can't just tell, ideas on how to test?
Thanks for your support.

 

[‡brandon]

Um. Bump* Sorry, just won't to keep this up for now.

Also on a bit more personal question, jeffy I see it says your in texas, what city? :p

 

[mrjeffy321]

The bleach method works, yes, as does the electrolytic method.

What kind of pot did you boil the bleach in before? Steel? If so, the brown stuff you are getting is likely Iron Oxide.

I cannot fill in the blanks in my above post as they are variables which have yet to be determined. The current through your cell is yet to be decided by you and Ohm’s law.
Once you know (or assume) a current, then the rest of the blanks can be filled in after doing a little math.
The rate of Chlorate production is dependent on the current through the cell, not on the amount of Chloride dissolved in the water (assuming it has a concentration > 10% or so). The amount of Chloride you dissolve in the water acts more to set a limit of just how much you can produce, total, by running the cell, not how fast it is produced.

I will give you an example….
If you dissolve 500 grams of Sodium Chloride in enough water to make 1 Liter of solution and run a constant current of 5 amps through the cell, then….
You will produce about 1.65 grams of NaClO3 per hour and it will take about 18.3 days to “finish” the run (meaning that the NaCl concentration has dropped so much so that the production rate is undesirably slow and corrosive to your electrodes), producing a total amount of NaClO3 of about 728 grams.
(I wrote a program to allow me to figure all of this out very quickly, but you can do the same if you work out the chemical reactions occurring and do all the math)

how do you exactly tell if its potassium chlorate? I know by looks you can't just tell, ideas on how to test?

If you are handed a mysterious white power and asked to find out what it is, then there are a range of tests one could perform to narrow down the possibilities. But you already have a good guess as to what it could possible be….either KClO3, KCl, NaClO3, or NaCl.
Simply trying to use the mysterious power as an oxidizer in burning sugar (KClO3 + sucrose, for example) will let you know if it is easier Sodium or Potassium Chlorate, as opposed to Chloride. Chlorate salts will obviously act as oxidizers while Chloride salts will not. This will help you figure out what the anion is in the compound.
Then if you want to determine where the cation is Sodium or Potassium, you could perform a fame test with the substance. If the flame turns yellow, it is Sodium, if it turns purple, it is Potassium. HOWEVER, a flame test with Potassium can be very hard to perform since even tiny amounts of Sodium impurities will color the flame yellow and hide the Potassium color, so unless you know you have a high purity substance, this might not be so definitive a test.

 

[‡brandon]

Ah thanks a bunch, I think you answered about all my questions. A few more though, think an aluminum can might work to boil it into prevent the iron oxide from occurring? It works for boiling, I've used it countless times as an improvision. And I thought potassium chlorate was non-flammable :p
Are you talking about whenever it is burned with the sugar?

 

[mrjeffy321]

The best choice for a boiling container of bleach would be Pyrex glass, for example an old [glass] coffee pot. I would be very hesitant about using an Aluminum pan. There is a little bit of Sodium Hydroxide in conventional bleach which will act to remove the Al2O3 coating on the Aluminum and allow the Aluminum metal to react directly with the water and Sodium Hypochlorite in a very corrosive way.

By itself, Potassium Chlorate is not flammable (just like Oxygen, for example). But if you mix it with a fuel (like sugar), the mixture will burn readily.

 

[‡brandon]

Hmm, any other ideas? I don't think I have any old coffee pots laying around. Although I think i might have one in the attic. Just out of curiosity besides lab equipment what else would be best to use?

 

[mrjeffy321]

You could still use the steel pot if you filtered out the rust from the Sodium Chlorate/ide solution before you extracted the Chlorate.
Iron Oxide is insoluble in water. Sodium Chlorate is very soluble in water. After you boil the bleach solution down, you can dilute it again with water to make sure all of the NaClO3 is dissolved (if any was precipitating out before). Filter the Fe2O3 out, and then proceed with the KClO3 extraction. Potassium Chlorate’s solubility will decrease dramatically at low temperatures, so adding a couple of extra hundred mL to the solution won’t rob you of that much KClO3 from your yield. After filtration, you could even re-boil the diluted solution down again, but this time you shouldn’t get any Fe2O3 formation since there shouldn’t be any bleach left (in theory).

 

[rashean123]

comment

mrjeffy i have read your past posts and it seemed you have helped me greatly,your persistence and effort and accomplishments have surprised me and allowed me to win numerous chemistry and science fairs ,eneyway, to make long story short, some of my friends and professors would like to thank you for the help you have given and insists that i post this.





one question, when i boiled down bleach to a concentrated amount,and added the chloride solution and left it to cool in the freezer no chlorate crystals were found, why is this so?

 

[mrjeffy321]

mrjeffy i have read your past posts and it seemed you have helped me greatly,your persistence and effort and accomplishments have surprised me and allowed me to win numerous chemistry and science fairs ,eneyway, to make long story short, some of my friends and professors would like to thank you for the help you have given and insists that i post this.

Wow, I did all of that? Cool.

one question, when i boiled down bleach to a concentrated amount,and added the chloride solution and left it to cool in the freezer no chlorate crystals were found, why is this so?

I will answer you question with a lot of my own questions about your specific experiment to try and get the obvious stuff out of the way.
How far did you boil the bleach down? You didn’t boil it all the way down to dryness did you?
You were using Sodium Hypochlorite (NaOCl) bleach, correct? Not some other type of bleach?
You got no precipitate at all? Did any Sodium Chloride precipitate out after you boiled it down and let it cool?
How much Potassium Chloride did you use? What was the source of the KCl – do you know its KCl and not NaCl or some NaCl / KCl mixture?

 

[rashean123]

I boiled one gallon of bleach to about 300ml.
I am sure i was using (NaOCl) bleach, not another type.
no precipitate-
no sodium chloride ether.
i used 60g of potassium chloride.
i know where it came from and i think it said about 99.8 percent purity, it came in a forty pound bag. i also did a flame test and it turned out purple, so i guess that's the correct chloride.

 

[mrjeffy321]

You boiled an entire gallon of bleach down to 300 mL and didn’t get any precipitate? That is very strange.
What brand of bleach were you using … I would imagine not Clorox.

Clorox bleach is a 6% solution of Sodium Hypochlorite with 5.63% Sodium Chloride, and a small amount of Sodium Hydroxide. So it starts out with a good amount of Sodium Chloride already in it.
Then, as you boil the bleach, the NaOCl will decompose into NaClO3 and NaCl,
3NaOCl ----> 2 NaCl + NaClO3
You product 2 moles of Sodium Chloride for every 3 moles of NaOCl you decompose. So by the time you are done with the boiling step and the volume has been significantly reduced due to all of the water driven off, I always got a fair amount of NaCl precipitating out, even out of the hot boiling solution and I would never boil it down as far as you did (proportionally speaking). The NaClO3 has a much higher solubility, so most of it will stay in solution.
But then when you added the KCl to produce KClO3, you should have defiantly seen some precipitate (possibly even before you cooled the solution) due to how low KClO3 solubility is compared to that of NaClO3.

You started out with 1 gallon of bleach. Let’s assume it has a density each to that of water. 1 gallon = about 3.85 Liters, and would have a mass of about 3.85 kg.
Assuming the bleach had the same concentrations of NaCl and NaOCl as Clorox, then you should have 217 grams of NaCl, originally, and about 231 grams of NaOCl which would decompose to form 121 grams NaCl and 110 g NaClO3.
You should end up with a solution of about 340 grams of NaCl and 110 grams of NaClO3.
The solubility of Sodium Chloride at 25 degrees Celsius is about 36 g/100 mL, and you only have about 300 mL of ‘water’ to dissolve it in. How is the other 110 grams dissolving in the already saturated solution? And this does not even take into account the NaClO3.

 

[rashean123]

apparently i did not use the right bleach, because the bottle said nothing about
Sodium Hypochlorite and it was not clorox.

I will try using clorox instead and post my results later

 

[rashean123]

I boiled down the bleach and there was a white precipitant on the edge of the pan, this is probably what u were talking about.
but when i added the chloride and boiled it it turned a medium brown color.
and i am currently at this step. i am going to try and crystallize it.
if i purify it would then brown crystals turn clear again.
oh and why is it brown?

 

[rashean123]

i have had my results and unfortunately... it wouldn't even light, i don't see the problem, i even tried the white powder at the bottom in thin pan and that wouldn't work ether.
i think i am doing something wrong or possibly i didn't follow a step.

i am going to try and do it again, hopefully getting it right. i will post my results later

 

[mrjeffy321]

What type of container are you boiling it down in?
If it is metal, this will likely account for the brown color. If at all possible, you should be using some Pyrex glass (or equivalent) when boiling the bleach.

On this most recent attempt you described, how much bleach did you boil down?
It sure was a fast attempt; it must not have been a very big batch.

Back when I used to use this method, here is a brief summary of what I would do (all numbers are rough estimates since I don’t remember my exact figures off the top of my head right now, but are pretty close).
I would start out with about 1300 mL of 6% NaOCl Clorox bleach. I would boil this in an old, Pyrex glass, coffee pot for several hours (since it took awhile to boil so much water away). I would boil it down to about 400 mL and then let it cool to room temperature. If a considerable amount of NaCl did not precipitate out already during the boiling process, it certainly would by the time the solution cooled down. I would then filter this NaCl out and then add the appropriate amount of KCl. Usually some KClO3 precipitate could already be seen forming at this point, but I would then boil it for a couple more minutes. I would then let it cool and place it in the freezer for several hours (if not over night). After several hours in the freezer I would take it out and filter all of the KClO3 which precipitated and let it air dry for as long as it took to dry out.
A good test would be to grind up the dried KClO3 crystals into a powder and mix with sucrose (table) sugar in a ratio of about 3 to 1 Potassium Chlorate to sugar.

 

[rashean123]

o i will try that.

 

[rashean123]

Ok i have followed all the steps and even used an aluminum pan, i boiled the bleach and added the chloride when i did that i boiled it some more, fortunately it wasn't that brown color anymore, it was actually a deep yellowish color,( b the way is it soppost to be that color?) and put it in the freezer, so far its bin one hour since i put it in (and by the way it was about five cups of bleach boiled down to two and one cup of potassium chloride), then i saw some white crystals at the bottom , about 1/4 of a cup, is this potassium chloride or chlorate? i have not done a flame test because i think its not done crystallizing.

 

[mrjeffy321]

An Aluminum pan would not have been my choice of containers to use…I am actually a little surprised it worked. Aluminum metal, lucky for you, develops a protective coating of Aluminum Oxide, Al2O3, which keeps the reactive Aluminum metal from oxidizing away, especially in as harsh an environment as a boiling pot of bleach. Clorox bleach does have a very small amount of Sodium Hydroxide, NaOH, in it (less than a percent). NaOH will eat away the protective Al2O3 coating on the Aluminum and expose fresh Al metal to be oxidized. But I guess your pan survived.

The deep yellowish color is OK. I have found the color of the boiled down bleach can vary somewhat. Usually it is roughly the same color as the original bleach, but sometimes it comes out a little darker or lighter in my experience when you are finished with the process.

If / When you get a KClO3 precipitate, it will be white. When you filter the KClO3 from the solution, a little bit of the solution will remain behind on the wet filtrate so when the Potassium Chlorate dries out, it might have a slight tint to it, but this will not affect the results.

Potassium Chloride, if I recall correctly, has a solubility of about 28.1 grams per 100 mL at roughly room temperature. Potassium Chlorate has a solubility of about 4 grams per 100 mL. So the KClO3 will precipitate out first. If your solution is not too concentrated, then pretty much the only thing which will precipitate out is KClO3. If you boil the solution down too far, then that is when you have to worry about other things (like NaCl and KCl) precipitating out too.

A flame test you perform will almost certainly come out to be yellow….an indicator of the Sodium ion. Even small amounts of Sodium impurities will overpower the purple/lilac Potassium flame test color. Just because it gives a yellow flame test doesn’t mean it is not KClO3, it just means you haven’t purified it yet, but this will not effect its reaction with sugar, it should still burn nicely.

 

[rashean123]

ok as of now i will filter out the crystals and dry them and do a flame test as you said, oh and if it burns slow is it still chlorate?
and should i use the chlorate mixture again to see if there are more crystals or am i just waisting time?

 

[mrjeffy321]

It might burn slow for any number of reasons, perhaps it is still wet and has not dried out completely, and/or it was not mixed in the proper ratio with the fuel (sugar). If it burns at all, it is a pretty good indicator that it is ___ Chlorate, and much more likely than not it is going to be KClO3 and not some other type of Chlorate due to the extreme difference in solubilities between KClO3 and NaClO3.

You will not be able to extra out any more KClO3 from the same solution unless you boil it down further and give the remaining KClO3 less solvent to dissolve in. But in doing this, you also increase your chance to get NaCl precipitates, which is not what you want mixed in with your KClO3.

 

[rashean123]

ok, by tomorrow i will post my results on how it went and if it lit or not, this time i will make sure its dry.

 

[rashean123]

oh and aside from chlorate, do you know anywhere where i can get red phosphorous or possibly make it.

 

[rashean123]

also about potassium nitrate, do you know a way i can make or extract that from soil,if so, what are the materials needed to do so?

 

[rashean123]

i have made a fourth solution in a stainless steel pan, the color seemed fairly normal, golden, and unfortunately when i crystallized it it would not light,even when it was powdered and added with 1/3 the ratio of it and it still wouldn't light, ma by its because i put it to boil for only five minutes but all of the crystals where dissolved, is this why?

 

[mrjeffy321]

At least you are getting a precipitate now.

You are using the 3 KClO3 to 1 Sucrose ratio by mass, right, not by volume?

i put it to boil for only five minutes but all of the crystals where dissolved, is this why?

Are you referring to the 2nd boil you did on the solution, after adding the KCl and filtering out the NaCl precipitate from the first boil?

 

[rashean123]

no actually the first

 

[rashean123]

yes by mass

 

[rashean123]

it seems like every time i try to make potassium chlorate it always ends up wrong , even to specific instructions, no matter how hard i try, it still doesn't even light, even with a blow torch.
these chlorate's seem very difficult to make.

 

[mrjeffy321]

no actually the first

The that could be the problem. What volume of bleach were you boiling? You are likely going to have to boil it much longer than that in order decompose all of the NaOCl and remove a lot of the excess water to make crystalization easier.
Remember, I said I boiled about 1300 mL for several hours down to about 300 - 400 mL. Unless your only using a small volume of NaOCl solution, it is going to take much more than 5 minutes.

 

[rashean123]

oooooooooh, that must be why, does that mean that the crystals that I've been trying to burn are not potassium chlorate and in staid potassium chloride

 

[rashean123]

i boiled about one liter of bleach to about 1/2 and added the chloride

 

[Overflow]

trying to understand things...

Hi all,
i tried to rationalize the proces, correct me if I'm wrong.

Molecular weights:
H20 = 18 uma
NaClO = 74 uma
NaClO3 = 106 uma
NaCl = 58 uma
KCl = 74 uma
KClO3 = 122 uma

1 liter of 5% NaClO
1 liter of water -> 1000gr -> 56 moles of water
i'd guess (correct me!) that this means in a 5% solution there are 53 moles of H20 and 3 moles of NaClO

Thermal decomposition should follow this formula
3NaClO -> 2NaCl + NaClO3

So, every 3 moles you get one mole (122 grams) of NaClO3 and 2 moles (116 grams) of NaCl

We will now need 1 mole (74 grams) of KCl

NaClO3 + KCl -> NaCl + KClO3

Which will give us 1 mole (122 grams) of KClO3

Which isn't theorically too bad, but my calculations differ from those given here ( http://www.wfvisser.dds.nl/EN/chlorate_EN.html#thermal [Broken] ) as he says to add only 28grams of KCl so i must be mistaken somewhere, but where? :grumpy:

 

[mrjeffy321]

1 liter of 5% NaClO
1 liter of water -> 1000gr -> 56 moles of water
i'd guess (correct me!) that this means in a 5% solution there are 53 moles of H20 and 3 moles of NaClO

The concentration of the NaOCl in the bleach solution is by weight….it is 5% Sodium Hypochlorite by weight, not by moles / volume / ….
If we have 1 kg of 5% bleach, then that means that we have 50 grams of NaOCl and 950 grams of H2O.