Making Potassium Chlorate

  1. mrjeffy321

    mrjeffy321 881
    Science Advisor

    I am trying to make some Potassium Chlorate (KClO3) by reacting bleach (NaOCl) with Potassium Chloride (KCl). I got this idea from this site:
    I am trying to do the first method using the NaOCl and KCl.

    I have followed the steps, kind of, and ended up with a dark browish percipitate. this is odd, since the reaction for this should yeild Potassium Chlorate, a white powder.

    NaOCl (aq) + KCl (aq) --> NaCl (aq) + KClO3 (aq/s?)
    add Potassium Chlorate to boiling/almost boiling bleach and get sodium chloride and Potassium Chlorate.

    to save you some reading on the linked site, i'll tell you how it should be done, and then how I did it.

    How it should be done:
    -bring bleach to almost boiling (instructions say 1 gallon)
    -add the Potassium Chlorate (instructions say 63 grams)
    -continue to let it react untill you get it to a specific gravity of around 1.3 (as measured by a hydrometer)
    -let it cool, put in refrigerator and let the Potassium Chlorate crystalize
    -filter out the crystals
    -repeat steps again with remaining liquid to be sure everything reacted
    -then add the stuff you get out of the filter to distilled water (instructions say 56 grams/100 mL water)
    -boil new solution
    -evaporate the water, and collect the Potassium Chlorate

    How I did it:
    before I started, I decided to work out this reaction on paper, and the theoretical amounts of each substance i needed, so i based my figures on that, but even if i dont get a compleate reaction, i should still get something
    -bring bleach to almost boiling (I used just over 1 liter of 6% bleach)
    -add the Potassium Chlorate (i dont know any more how much I used)
    -continue to let it react untill you get it to a specific gravity of around 1.3 (well I had a hydrometer, but I dont think it is very accurate, so i let it sit there for a long while, untill I was pretty sure it had reacted all it was going to do, but the number [approx.] I was getting on my hydrometer was 1.15)
    -let it cool, put in refrigerator and let the Potassium Chlorate crystalize
    -filter out the crystals
    -repeat steps again with remaining liquid to be sure everything reacted

    I am currently at this step, I havent gone this far yet

    -then add the stuff you get out of the filter to distilled water (instructions say 56 grams/100 mL water)
    -boil new solution
    -evaporate the water, and collect the Potassium Chlorate

    I dont know how much of a diference these last 3 steps will make, but I doubt that they will take my dark brown stuff and make it into good 'ol Potassium Chlorate, (unless im wrong, i dont know)
    also, the vapor that is comming off this liquid solution while boiling and going out the exhaust suction, some of it is condensing around the grill plate and it is becomming a whitish powder, but then when I go to wipe it up, it looks much more yellowish on the paper towl I use, what is this stuff, in theory the only thing to evaporate in this reaction is water which last time I checked wont leave a residue behind.

    I just though that maybe someone here could offer me insight into what is happening and, what should be happening.

    just so you guys arent worried (to much) about my safety while doing this [this seems to always come up when I do something dangerous (thermite)] I will tell you that I know what Potassium Chlorate is capeable of, and I am doing the boiling with a ventalted exhaust near by, I wont be eating any of this either.
  2. jcsd
  3. chem_tr

    chem_tr 613
    Science Advisor
    Gold Member

    Hello, I will only discuss the redox chemistry of the reaction, maybe the reaction needs reviewing.

    Cl+ + 2e- ---> Cl-
    Cl- ---> Cl5+ + 6e-
    3ClO- + Cl- ---> 3Cl- + ClO3-

    We may even simplify it by subtracting the chlorine on the left:
    3ClO- ---> 2Cl- + ClO3-

    So, you should check the concentration of bleach; as you see in the redox reaction, three moles of bleach is needed to produce one mole of chlorate. Also, brown precipitates don't seem normal, please check the purity of your substances. Use distilled water as much as possible. If there are particles in your starting solutions, don't let them interfere with your business, just filter them off.

    I haven't checked your concentrations, since we use SI units in Turkey, I am not familiar with gallons, etc.


    Check out that link and try using his procedure instead.

    I'm inebriated at the moment so I'm unable to see why your procedure is wrong.

    But assume that the link I provided will give you a procedure that WILL work (the guy who made the site is highly respected).
  5. haha
  6. Gokul43201

    Gokul43201 11,044
    Staff Emeritus
    Science Advisor
    Gold Member

    We really can't say much about the quantitative aspects for 2 reasons :

    1. We don't know how much you've used (we could tell you how much to use, but it seems you've already figured this out)

    2. Like you said, the problem seems to be not about how much, but rather about , "what the #$%^ is this brown/yellow stuff and where did it come from ?"

    Okay, here's my five cents :

    1. Do you buy KCl from a Chemical Supply or do you use some kind of Lo-salt ? If you buy from a chemical supplier, they might just sell you KClO3. If you use LoSalt, you might want to check on the other components. Most LoSalt is only about 70% KCl, so there's lots of other stuff.

    2. There may be impurities from water or bleach. Why don't you use sodium chlorate (weed killer) instead of bleach ? I'm sure that's the more common approach.

    3. Have you tried a basic flame test on your brown precipitate and your yellow condensate ? If you see colors other than lilac, that's a strong indication of impurity. Incidentally, potassium hypochlorite is a pale-yellow salt. Often, a little salt can be carried away by the steam ...depending on the size of the crystallites/particles - especially with vigorous boiling.

    {Hmmm...first the thermite, then potassium chlorate. The word that comes to mind - pyrotechnics. I hope it's nothing more sinister than that.}
  7. mrjeffy321

    mrjeffy321 881
    Science Advisor

    this procedure seems very similar to what I was doing, althugh the above procedure seems to need very concentrated solutions of both bleach and potassium chlorate, something that I am probably not getting close enough to.

    I am getting my potassium chlorate from a salt substitute (walmart), but this isnt one of those reduced salt ones, this is suppose to be no sodium stuff.
    and I am using bleach that starts out as 6% by weight.

    I did try burning some of it, but I dont think anything happened, i just burned the remnents of it that I couldnt scrape off the filter, but i just think that the filter paper is what burned, not the brown stuff. I am now evaporating the water off the "cleaned" brown stuff, so once it is dry i will be done with all those steps, but I barely have anything to show for it.
  8. mrjeffy321

    mrjeffy321 881
    Science Advisor

    actually, I think now I will try to do it the way that is in that link you gave me, with the high sconcentration solutions.

    but I just cant figure out why I am getting some type of brown percipitate forming, could it be because I am not using a high enough concentration of something? or not getting it hot enough?
    when I filter out the percipitate, I get (what looks like to me) a highly concentrated bleach solution, it smells like bleach and looks like bleach, just darker, and when I try to make more potassium chlorate using the same method with the "new" concentrated bleach, the same thing happens.

    maybe I should incest in a good electronic hydrometer, not rely on the leaky, possibly broken, old battery hydrometer I had.
  9. mrjeffy321

    mrjeffy321 881
    Science Advisor

    OK, last night I (tried) to make a very concentrated solution of Sodium hypochlorite, but I may have only partialy succeded.

    I took about 1 liter of 6% chlorox bleach and boiled it until it was about at 200 mL, then as I was letting it cool, I added some tap water to try to redisolve some of this stuff that has come out of solution ( i dont know what exactly it is, possible sodium chloride?, or NaOCl that came out of solution?) then I let it cool some more. afterward I filtered the solution twice with a pair of coffee filters, an collected alot of dark k and some other stuff that could be sodium chloride (since I think when you heat the bleach, some of it becomes sodium chloride). so I now have a solution of around 300 mL of what should be concentrated bleach. I will describe the solution:
    a dark yellowish color (similar to dark urin, especially when it was still warm)
    it smelled like bleach

    I didnt add anything else to the solution while it was heating, just let the steam evaporate away. the vapor comming off theoretically should be steam, H2O(g).

    but all this brown stuff that was made is concerning me, what is it and why is it there? it is just like the stuff that I had when I was trying to make potassium chlorate the other way. and while boiling the bleach, it got very dark in color, almost pure black, a very dark bown, but then went back to the dark yellow when it cooled, leaving some type of percipitate.
  10. mrjeffy321

    mrjeffy321 881
    Science Advisor

    Success, kind of

    I have tried 2 trials, and I am preparing the 3rd trial now, here are my results:
    trial 1 - used only a 6% blech solution and not very much KCl, I only get brown stuff
    trial 2 - used much more concentrated bleach solution with much more KCl, and here I did get some KClO3 crystals, not much, but some
    I tested to see if it was KClO3 by adding sugar to it and burning it, I couldnt get it to burn very easily without the sugar, but the flames resulting sure arent any regular sugar flames I have ever seen, very bright, light blue flames, burns very quickly.

    trial 3:havent done yet - I will use MUCH more concentrated solution of bleach, and a saturated solution of KCl, so in theory, this should work best.
    I wonder if I will need to heat the solution(s) to get them to react, or will room temerature work just as well? I probably will get fater, more compleate reults if I heat it.

    Is there a point of maximum saturatation for bleach (NaOCl)?, were even if I try to get it more concentrated, I cant, i'll just be waisting my time?
  11. mrjeffy321

    mrjeffy321 881
    Science Advisor

    OK, I am not totaly clear on how exactly I obtained this substance, my best guess would be from when I was making concentrated bleach and then filtered it to get the particles out, which I thought was sodium chloride but just for fun one night, I decided to test to see if it really was by trying to burn it with sugar like I did with the other stuff i had made, and to my surprize, IT WORKED. now I know this stuff just isnt sodium chloride anymore, and I think I got it from what was a relativly pure solution of what was bleach, I just filtered it out and dried it.
    So now I have 2 substances, one I got in my "trial 2" described above using a more concentrated bleach solution and lots of potassium chloride and it burns with sugar to produce a white/light purple flame, so I would have to say that my first substance is potassium chlorate. my second substance I think I just got by heating up the bleach, getting it more and more concentrated and making more and more salt, then perhaps could the sodium chloride have reacted with the bleach and made sodium chlorate perhaps? my substance 2 burns with sugar to produce a much more yellowish flame.
    (now remember these colors that are being described are my opinion of what color it is, which may be slightly flawed because I am color bind, but I other people who have witnessed my reactions describe the color similary)

    I have looked up what color both sodium and potassium chlorate should burn like:
    I have also video taped the 2 substances burning on my computer, it is kind of hard to tell colors though becuase of the brightness of the combustion, but someone might be interested in seeing it, but I cant attach it becuase my 1.2 Mb file it too large, so here is a link to it on a geocities page:
  12. mrjeffy321

    mrjeffy321 881
    Science Advisor

    well no one seems to be reading this, or at least responding, but I will keep posting my status, for a while anyway, it helps give me a chance to rethink some of this stuff while writting it,

    When I was making my concentrated bleach solution, I boiled down over a liter and a half of bleach to around 400 mL, so it should be extreamly concentrated, in theory. well as it was boiling, it did as I expected, made that brown stuff, then I filtered it, then continued boiling and no more brown stuff was made. I am concluding that the brown stuff is the result of some type of reaction that is occuring in the 94% other in the bleach (6% sodium hypochlorite, 94% other, not all water I suppose).then once its gone, it is gone. then when it started getting lower, I started seeing large buildups of a white crust on top, and globs of a while powder at the bottom of the pan, ( assumed it was sodium chloride), so when I got done boiling it, I filtered out the "salt", then let it dry. later I decided, "hey, what the heck, i'll test the "salt" and try to burn it with sugar like I would do with the potassium chlorate, and to my surprize, it worked (like I told you all in an earlier post, I assume the "salt" is actualy sodium chlorate resulting from sodium chloride reacting with the sodium hypochlorate).
    but now lets get back to the concentrated bleach solution, if you can call it that, since it exibits almost no bleach properties any more, it doesn whiten fabrics, it doesnt smell like bleach (it smells like something familiar, but I just cant place it), it doesnt react like bleach, as a matter of fact, the only 2 reasons I once though it was bleach are because it was made from bleach and it had a dark yellowish color. what I am thinking now is that while boiling, some/most of the bleach was reacted and made oxygen gas and sodium chloride, then intern, that sodium chloride reacted with the remaining bleach to form the sodium chlorate, but leaving the bleach color behind. if you havent watched the videos I put up, I encourage you to, although it is hard to tell colors because of the brightness of the flame, you can (and me especialy since I was right there) see the color diference in the 2 combustions. I have also tried to make more potassium chlorate with that concentrated "bleach", but was unsucessfull even using highly concentrated solutions of potassium chloride.
  13. mrjeffy321

    mrjeffy321 881
    Science Advisor

    I have now made some chloate (potassium I guess) using the calcium hypochlorite method. i found it to b less labor intensive than the bleach method, becuase I started out with my solutions at the correct concentrations allready and I didnt have to boil down and destroy the stuff that I needed in the first place. but that method is harder, since I dont have a good supply of pool shock (calcium hypochlorite) and it seems to be more corosive on my pan that I used than the bleach was.

    I think I will try to do the electrolysis method not, even though I will like that one the least, but technicaly it is the most efficient and less labor intensive of the three.
  14. Man, your persistant, that's for sure!

    What are you going to use the stuff for?
    fireworks? amateur rocket-engine?
  15. mrjeffy321

    mrjeffy321 881
    Science Advisor

    actually, you just listed my two main things I want to do with it, general pyrotechnics fun and model rocket fuel.

    well, yes, but mainly no one is really responding anymore, I just use this a a place where I can recount my experiments, and by doing this I kind rethink them in my mind so I dont loose any details later if I forget, plus is anyone responds, thats good too! but that hasnt happened in a while, the last 7 posts were mine. and maybe later on, month or years from now, someone else can benifit from my experiences if they are trying to do what I am doing. if anyone would like to contribute, by all means, join in.
  16. mrjeffy321

    mrjeffy321 881
    Science Advisor

    OK, this is actually a question, not just an update on what I am doing now:

    using this page for a source of ways to make potassium chlorate,
    it disscusses an electrolytic method that uses sodium chloride as an electrolyte in water, and then runs a current though the water to turn the sodium chloride in to sodium chlorate (from NaCl to NaClO3) because of a lenght series of reactions that are explained on the page.

    my question is, could I not just take bleach (Sodium hypochlorite, NaOCl) and electrolysize that, since it is allready in an aqueaus solution, therefore only needing to add 2 oxygen atoms to the compound, rather than the 3 atoms using the other method. (from NaOCl to NaClO3?)

    I have found out that normal cloroz ultr bleach is composed of:
    6.00% sodium hypochlorite (NaOCl)
    5.63% Sodium chloride (NaCl)
    0.015% caustic soda/sodium hydroxide (NaOH)

    it seems like this reaction in question would be perfect to make sodium chlorate becuase it will require less time/energy to add only 2 oxygen atoms (rather than 3) and it contains sodium chloride aswell for the old reaction, and the .015% sodium hydroxide wont last long anyway once everyting gets started.

    will this work?
  17. mrjeffy321

    mrjeffy321 881
    Science Advisor

    I would very much like to know if my idea from above would work, taking a shortcut by electrolysizing bleach insted of salt water.

    I know bleach can be made by electrolysizing saltwater, but cant you just keep on going and make sodium chlorate too?
  18. mrjeffy321

    mrjeffy321 881
    Science Advisor

    I have went ahead and electrolysized the bleach, and here is what happened:

    I let it run for about 20 hours to get these results,
    the solution has lost its distinctive bleach color, it is now much more clear after being filtered to remove the gunk produced as a result of the elctrolysis process. it isnt totaly clear like water, but if you arent carefull, you can mistake it for water.
    the smell, it has a chlorinated smell, similar, but somehow more chlorinated than bleach normally smells like (probably because of all that chlorine gas produced), but it isnt a stong a smell.
    it has lost most of it's bleaching property on fabric, still will somewhat whiten fabric, probably becuase it isnt totaly finished electrolysizing.

    other than that, that is all to report for now, still wished I knew what I should be expecting fromt this.

    I think when doing this, the pH should rise throughout the process, and the pH starts out at about 11.4 anywar, but in order for me to get effective results, I think I need someone around 6. but in bleach production through electrolysis, you want a high pH, is it possible I could be making MORE rather than less bleach? but this wouldnt be likely because of my results.
  19. mrjeffy321

    mrjeffy321 881
    Science Advisor

    I have answered my own question about whether it will "save a step" by electrolysizing an aqueus solution of sodium hypochloite (NaOCl) insted of sodium chloride (NaCl) to make Sodium Chlorate (NaClO3).
    the Answer: No, although i will end up making the same thing in the end, since oxygen is made while electrolysizing the sodium hypochlorite electrolyte (and let to escape from the system), it takes away precious energy that could be used somewhere else, but is insted lost. When electrolysizing the aqueus sodium chloride solution, very little to no oxygen is made, energy more or less goes into making the chorate. If you go and calculate the theoredical energy need for both methods, the sodium chloride method would need something like 6 fardays/mole of chlorate, and with the sodium hypochlorite method, it is something around 9 fardays / mole of chlorate.

    I have disscussed this with a diferent, more knowlegible, chemestry teacher, and she is under the impress that I am doing the impossible, what I am trying to do (and the results I am getting) should not be happening, and I understands why she thinks this, because all the stuff I am using to make gthe chlorate and the chlorate itself is soluble in water (some of the substances more than others), but she thinks that everything will end up being dissolved and I wont get anything to precipitate out. and yet, experimentally, I know that I infact do, and the stuff that does percipiatate out, has properties very similar to that of the chlorates that I am trying to male (sodium and potassium chlorate).
  20. mrjeffy321

    mrjeffy321 881
    Science Advisor

    like i said above, the chemistry teacher I talked to doesnt think that what I am getting is really chlorate, but rather some kind of hydroxide(thats what she says), but I think I am actually getting a chlorate based on the reactions that I can produce with the stuff I get and all the "people"/souces that I have with similar instructions on how to make it.

    is there anything that I can do to prove/test what I am getting to see what it is, if it is a chlorate or not? I thought that flame test with sugar was pretty good proof, especially with the distinctive colors I saw, but is there anything else?
  21. chem_tr

    chem_tr 613
    Science Advisor
    Gold Member

    You may have obtained a peroxide, as it helped burning. You can try treating the solid you obtained with hypochlorite, and if it is chlorate, all of them might be converted to chloride, easily detected with silver nitrate.
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