What Went Wrong in My Attempt to Make Potassium Chlorate?

[mrjeffy321]

I first got the idea for the program from this site (program link at bottom),
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/table54.html
the two programs give the same ansers, so either we are both wrong, or both right.
In the program, I found out how much charge must be used to convert x amount of chloride to chlorate, I believe it is 6 faradays per mol of chloride converted, then it is simply a matter of adjusting for efficency (I think if you just leave the cell alone and not try to adjust pH or anything, you average about 50%, so that is the default efficency in the program).

 

[jeffomatic]

I make potassium chlorate by electrolyzing "diet salt". I use a 1 quart stainless steel kitchen pot with a glass lid that has a hole in the middle, left after removing the plastic knob. I made an anode holder that fits in this hole. I use battery carbon for the anode and a hefty battery charger for the source of DC. I mix a concentrated solution of the diet salt, then start the charger on the lowest (6 volt) setting. I adjust the depth of the anode to get 4 amps and let it run for 24 hours. The I filter the solution and boil it for a while and set it in the fridge. The potassium chlorate crystals will precipitate first. The solution decanted can be returned to the electrolyzer and more salts and water added for another batch. The crystals can be washed with ice water to clean them, then re-disolved in hot water, boiled and crystalized again to purify them.

The diet salt works great, it is a mix of half NaCl and half KCl. The only trouble is that it contains iodine too. It takes extra filtering, as it turns the whole solution dark reddish brown. I filter the iodide out with a cloth filter in a funnel, followed by a toilet tissue wad in a funnel to get more of it out. The iodine forms a dark brown glop which filters out reasonably well, but the filtered solution is still somewhat yellow.

Don't get copper or other metals in the chlorate because it can make it unstable. I only prepare it in small amounts because of the potential for instability. I store it in the fridge with a loose-fitting lid. Don't mix KClO2 with things until you are ready to use it, especially sulfur. Assume all mixtures using chlorates can be impact sensitive, so don't tamp them into any container. Read all you can about hazards and mixtures before messing with chlorates!

 

[mrjeffy321]

The diet salt works great, it is a mix of half NaCl and half KCl. The only trouble is that it contains iodine too.

Don't mix [KClO3] with things until you are ready to use it, especially sulfur.

I don't think using diet salt is the best idea, since you have both NaCl and KCl, you will be making KClO3 as you are electrolysizing the solution. Since KClO3 isn't very soluble, it should percipitate out, so when you filter the dirty solution, you should be loosing some of your product. I still think it best to use just plain (cheap) NaCl to make NaClO3 first...then turn it into KClO3.

You salt has iodine in it? I have got to get me some of that. No, more likely than not, it has Potassium or Sodium Iodide in it, and a very small percentage at that. I think ordinary salt has about .02% NaI by weight, I am not sure about your brand of diet salt, but I can't imagine it is too much higher since in reality, the body doesn't need but just a very little amount.
However you seem to be descirbing that you find iodine crystals/blobs in your solution, implying that there is a lot of Iodine being make, perhaps from a lot of NaI in your salt. Does it have a list of ingrdients or something on the side with the % of everything?

You shouldn't be mixing KClO3 with sulfur anyway, don't even bother being careful because you shouldn't put yourself in that situation.
But yes, you need to always becareful when mixing KClO3 with a fuel to burn with, but I have found that KClO3 and sucrose is reasonaby safe/stable to be stored (not that it is a good idea to make a bunch and let it sit just to test the theory). In other words, don't mix it until you want to use it.

 

[gravenewworld]

seriously, what is up with this thread? why doesn't it ever die?

 

[mrjeffy321]

seriously, what is up with this thread? why doesn't it ever die?

Its no longer a thread, it is more of a steel cable now that it has grown to 9 pages long, granted there are longer threads out there, but this one is my favorite for some reason.


And by the way, as long as I am posting, I might as well post some useful KClO3 info pertaining to my experiments.
I have run two more trials in a newly designed cell (actually 2 separate cells but the same design). I have the electrodes positioned at the bottom sticking up through the solution with an open top.
On the first trial with the new cell I had some...interesting...results.
I have 220 grams of NaCl in solution with 600 mL of water. I began assuming 55% efficiency, so I needed to put about 800 amp hours through the cell. Then about half way through the trial, something happened, I don’t know what, but I must conclude it had something to do with my graphite anode eroding away and the solution turned green-ish brown and it wouldn’t filter out. I ended the trial, and long story short I think I had some copper compound that was some how introduced. I ended up making 58.7 grams of slightly off-white colored KClO3 after 403.1 mp hours, giving me an efficiency of about 40%.

After the above trial, I found my cell leaked for some reason, so I rebuilt it new, using the same design, then only difference was that I made a slight change to the electrodes. I greatly increased the surface area of the anode (about double the previous SA) and soaked it in linseed oil for 5 days, let it dry and then installed it in the cell. I had much better results. I did a smaller trial so I could get finished quickly to see how well my changes worked.
I assumed 50% efficiency at the start, dissolved 80 grams of NaCl in 500 mL of water and passed 170 amp hours through the cell. This time the new anode worked wonders, much less (but still considerable) amounts of graphite powder was left in the water and less visible erosion was detected. I ended up making 56.2 grams of KClO3, giving me 43% efficiency. However, this entire trial was designed to be a very quick and dirty experiment to test the new cell and anode design, I didn’t even worry too much about pH control, I am very pleased with the results.

I usually don’t bother to purify my KClO3 after I filter the precipitate out of the solution the first time, causing it to burn with a yellow color (instead of the purple color it should have), but since I got an off-white KClO3 in the first trial I mentioned in this post, I decided to try it.
The color improved, it became much cleaner, but still not the snow white I am used to getting, and it still burned with a yellow flame, so apparently the purification process isn’t fool proof, but what I might do is take maybe 100 grams of the "good" stuff I have just sitting around and try to purify that. I would prefer the purple burning powder, but for what I use it for, the color doesn’t matter much.

 

[dx/dy=?]

Keep it up mrjeffry.

Your perserverance is inspiring.

 

[Cesium]

I'm wondering what thoughts anyone has on preparing KClO3 with K2CO3, described here: http://www.frogfot.com/synthesis/chloratedisprop.html

3K2CO3 + 3Cl2 ==> 5KCl + KClO3 + 3CO2

Ways of making K2CO3:

Fractionally crystallize K2CO3 from Na2CO3 and K salt or

5C12H22O11(s) + 48KNO3(s) => 24K2CO3(s) + 36CO2(g) + 55H2O(g) + 24N2(g)

HIGHLY exothermic and often does not go to completion.

Or make NaClO3 first from Na2CO3 then add KCl to get KClO3

Or can K2CO3 be purchased?

Thoughts, problems, or experience are appreciated.

 

[mrjeffy321]

I don't know anywhere off hand to get any Potassium Carbonate, but perhaps it could be obtained by heating baking soda (Sodium biCarbonate) to make Sodium Carbonate, water and Carbon Dioxide.
Then using a double replacement reaction with KCl, turn the Na2CO3 into K2CO3. Sound good?
I don't like the idea of burning Sugar and Potassium Nitrate to make K2CO3, for one because it is unnecesarily exothermic (it makes for an impressive reaction, but why burn something just to get the byproducts), also, as you stated, you are assuming the combustion is 100%, which we know it will not be, therefore you'll have a bunch of other stuff mixed in with your K2CO3

How do you propose to make and bubble the chlorine through the heated solution? This method seems a little complex and time consuming doesn't it, especially since you making 5 times the number of moles of KCl in the reaction as you are of KClO3.

if you try it, I would love to hear the results and your impressions.

 

[Cesium]

Mainly just throwing it out here because this thread is the ultimate source for all questions dealing with KClO3. I guess I am just frusturated with the difficulty in predicting the yields of NaClO3 by electrolysis of salt and the amount of variables that are involved. But then again, my power source is sucky and I still don't have a multimeter, so I haven't really given it my best shot.

Cl2 would be generated with sodium bisulfate (or any acid) and bleach. I did this as a test and it made LOTS of chlorine gas with tiny amounts of each reagent. If you ever need chlorine do this.

 

[mrjeffy321]

While I am thinking about it, let me just post my results from my recent purification of the "impure" KClO3.

I started with 100.0 grams of KClO3. it had enough [Na] impurities so that when it combusted with Sugar, it was yellow rather than violet.
I dissolved it in about 200 mL of boiling water, le it boil for a little while, then cooled it. Afterward, I stuck it in the freezer overnight only to find that it had frozen solid (which doesn't lend itself to easily filtering out the percipitate) so I had to thaw it and then cool it back down in the refrigerator and then briefly stick it in the freezer.
By the time I filtered it, the solution was somewhere between the highly scientific temperature range of "refrigerator" and "freezer" temperature.

I filtered it, dried it, and weighed the KClO3 extracted back out to be 81.5 grams. When I combusted it with sugar, the light it gave off was very bright more than anything really. There was still some yellow, but it had shifted considerably towards bright white and perhaps just the faintest of hints of violet. So I ended up loosing about 20 grams of KClO3 in order to make some slightly more pure, but hardly noticible, KClO3 cystals.

 

[Cesium]

Keeping this thread alive!

I am happy to report that my first proper attempt at making potassium chlorate was a success. I pretty much used the most OTC methods possible so my cell wasn't too great. 70g NaCl in 200mL water with a graphite anode (from old lantern battery) and stainless steal (4" cap screw) cathode in a polypropylene container. Electrodes were usually around 2-5cm apart and I tried to keep the temperature around 40-50C. Electricity came from a computer power supply of course at 12V (way too much I know...should have hooked multiple smaller cells in series but I only thought of that three-quarters of the way through!) and the current averaged 2.11 amps. HCl was added once or twice a day, but I didn't bother to measure pH. The cell was run for 115.9 hours for a total 9.14 faradays; this corresponds to a 56% efficiency. Of course, the standard horrible and yucky way of logging the amps periodically was used to calculate the approximate charge. This was the only part of the process that was at all annoying...the rest was easy and quite enjoyable

The jet black solution filled with the graphite sludge of several anodes was filtered three times and then boiled to destroy residual hypochlorite. At this point I had a yellow solution (Fe+2) tinted brown due to collodial graphite that could not be removed by filtration. I added 65g of KCl (salt substitute) to 250mL of water, mixed the two solutions, boiled the mix down, and began crystallization. This crop of needle-like crystals were discolored yellow and green due to iron and chromium impurities, respectively (and probably some graphite too). I then redissolved and recrystallized them, washed them with ice-water, and dried them in a toaster-oven. I ended up with about 48 grams of a nearly perfectly white powder which is a 46% yield. Not too great, but I think I actually needed to run the cell longer.

This is probably the only section of my post that merits a response. The stuff burns with a nice lilac flame, but it tests positive for chloride ions when silver/copper nitrate is added (a white precipitate forms). The flame color, however, indicates that they are very few sodium ions in the product. I guess there could be KCl but doesn't make too much sense due to its higher solubility. There were some other impurities listed in the salt substitute (calcium or magnesium silicate and something else that I can't remember) so perhaps this is what is precipitating. Or else there are just so few Na+ ions in there that there are overpowered by the K+? This is doubtful because flame tests are very sensitive to sodium ions...odd.