Scrap Science - 2020-11-18
We do our best to follow a 100 year old paper describing the synthesis of permanganate from manganese metal. DOI of the paper: 10.1021/ie50141a012 Link to the video where we make manganese metal: https://youtu.be/wBWba_anewQ The setup is very simple, using a separated electrolytic cell (with a clay pot diaphragm) and a 25% potassium carbonate electrolyte, we use a manganese anode to make permanganate at a high efficiency. In doing this, we were able to make approximately 1.5g of potassium permanganate as a 0.21M solution. Sadly, we don't manage to crystallise any pure permanganate from solution. This electrolytic method offers some serious advantages over most other permanganate syntheses in that it offers a high efficiency and is capable of generating a highly concentrated solution (possibly getting close to saturation). It also doesn't require aggressive oxidisers or high temperatures. The only major downfall of this pathway is the fact that it uses manganese (or ferromanganese) metal as a starting material, which is a little difficult to get hold of. In the future, I'll definitely be revisiting this by attempting to make a manganese electrode from manganese sulfate (a much more available compound) and using that as the manganese source for the electrolysis stage. This video is basically just a proof of concept for the process, so I haven't attempted to calculate the yield or efficiency of the reaction. Again, this is definitely something I'll revisit in the future with a bit more of a controlled setup, so stay tuned!
I think cycles of evaporation to a super saturation state, followed by cooling would have resulted in better crystals. Heat destroys permanganate crystals.
I love your videos so much man keep it up I'm always looking forward to the next one!
I'm super interested in chemistry and learning new ways to make things
honestly I'm really surprised your channel isn't bigger than what it is but it definitely has the potential to grow huge
If you check Sreetips' channel, in his silver electorefining cell he uses a basket of metal pieces to provide a large anode area and make it easier to connect to the current source. This might be a useful technique in other electrolysis setups, too.
Great process it seems like evaporating in a large wide glass dish would help. I'm wondering if using Bismuth and manganese as an anode would help. This chemical is so tricky it even reacts with filter paper which using glass wool is the only way
As far as crystallization goes temp changes are a problem. You gotta dry it. I leave it open to the air in a dry place for weeks and it will grow crystals. Crystals don’t like to grow fast
I read on wiki that pyrolysis of zinc acetate can give acetic anhydride, maybe you should try it?
@Дамир Махмутов a corporate crime!!
Дамир Махмутов https://youtu.be/_1mMW2qEF84 pretty stupid to have done this then. afaik, acetic anhydride isn‘t a precursor to drugs but used to put drugs in a form that isn‘t technically illegal or smth (or just used to modify already illegal drugs) so it itself isn‘t illegal to be synthesized but might be illegal sell.
@Gian Sieger also great for esterifications
@Gian Sieger it is unlawful to harm someone with the acetic anhydride
Sammy D it‘s unlawful to harm someone
Very cool! Too bad about the crystallization. I can't remember what solvents and technique I used to extract and recrystallize KMnO4 from these packets that you put in the refrigerator produce bin to extend the shelf life, but I was able to do it. I want to say I ended up extracting an aqueous solution multiple times with DCM, hexane or something like that. Trying to crystallize from water resulted in mostly MnO2 I think.
I was really rooting for you that you'd be able to separate the permanganate, sorry it didn't work out. I did a synthesis of this once but it was one of the high temperature variants. I had basically the same result. Lots of dark purple reactive solutions but no solid. I tried slow evaporation as well and that didn't work either. I just got a sludge of manganese dioxide and potassium hydroxide. If I revisit this and figure anything out you can be sure that I'll let you know.
Hi. I love your videos. I do have an idea for making a possibly better membrane for your experiments. I haven't tried it yet but it should work.
1. Grind some salt (table salt, rock salt, etc) into as fine a powder as possible. The finer the better. (Best to use a ball mill for the finest particles).
2. Take some HDPE plastic from either a milk jug or a shopping bag and melt it in a small pan over a hot plate. Make sure that you use enough plastic to make a thin sheet and that you put the hot plate on a low heat, just enough to melt it.
3. When melted add the salt powder into the plastic and stir it with a spoon or stick until both components are mixed thoroughly.
4. Make sure that you spread out the plastic/salt mixture as thinly as possible. Turn off the hot plate and take the pan off and let the mix cool.
5. Take off the plastic/salt film and then soak it in hot water to dissolve the salt away. Repeat this step several times to ensure that all the salt has been dissolved out of the plastic.
This will make a porous film that will hopefully be better than using a clay pot as a diaphragm since this is thinner, allowing for both more electrical current and ions to flow through. You can probably make it even better if you add a small amount of graphite powder to make it more electrically conductive. I hope this idea helps you with your experiments. Cheers.
I've given this type of setup a go a few times in the past (with different plastics like hot glue or HDPE), and I'm afraid the plastics pretty much invariably coat the salt particles (or anything else I'm trying to encase) in a waterproof film such that the salt can't be dissolved out of the structure.
I dunno, maybe I'm doing something wrong. Do you have any ideas on how the salt particles could be 'exposed' in the structure for proper dissolution?
@Scrap Science Maybe you could try to scrape the surface of both sides of the membrane with some grades of sandpaper, each time do so lightly, this would thin out the membrane further but don't thin it out too much. First with some course grade, then with some fine, and lastly with some ultrafine which you can probably get off the internet. Make sure that you rub each side lightly, especially with the course grades as to not create large holes in the membrane. Then I would wash it in pure water to Also, it might take a bit longer if the membrane is mixed with graphite (since it is a lubricant) but to increase electrical conductivity. I'd give it a shot. If not, then you could also try to thin a piece of clay pot with a sand blaster or something. Just make sure to wash the clay piece out really well to get the dust out of the pores.
Hi there. As someone who's attempted permangenates before I know how tricky the actual extraction is. My suggestion is to pay attention to PH when boiling down your solution. Permangenates break down at a Ph of around 10 back into mangenate, so keeping the ph neutral is quite important as it will rise with the removal of water. Also, permanganic acid is pretty unstable and will break down during the boiling of the soloution.
Thanks for the tip! I probably should have put a lot more effort towards neutralisation when I was trying to crystallise the permanganate. I did do my best to acidify with bicarbonate but didn’t realise how sensitive the pH adjustment actually was.
Next time I’ll be prepared to do it properly.
I really enjoy your videos. As a suggestion, could you please find some better illumination for your experiments? LED lights are so bright and cheap I'm disappointed that at times we can't really adequately SEE the results of your considerable work. Keep it up!
Gday mate! New follower to your channel, love your work. I've been messing with home chem for a couple years now (mostly simple synthesis for crystal growing) and have had no luck whatsoever getting permanganate crystals to grow nicely, even through recrystallisation from pure crystals. Its an absolute nightmare of a chemical to crystallise from my (albeit small) attempts.
That aside, its awesome to see a cool synthesis method! I've been meaning to get more creative with electrolysis and you're giving me mad inspiration.
Keep up the awesome work!!
Maybe we need to crash it out of solution using a solvent or use high vacuum for room temp evaporation of solution.
Based on colour, I had a prototype instrument that could measure 10 PPM , it is very intense.
Could you try to make Ferrates? I think the electrolytic process is pretty similar to the one shown in the video. Instead of manganese iron would be used as the anode.
That's an awesome idea!
Doing some research into the process, it looks like ferrates are a lot trickier than permanganates, so it's unlikely that anything above a low concentration could be achieved, but I'm keen to give it a go at some point.
I'd expect your bisulfite titration values to be affected by other alkali impurities, and color+turbidity to actually be more accurate for permaganate content with a less eyeball-based measurement (cell phone camera light level sensors come to mind for a hack maybe). Recycling the electrolyte got the cell running, but topping off with potassium carbonate solution might have kept the product cleaner. Fantastic work regardless, it's amazing what can be accomplished with humble but pure materials, a little electricity, and a lot of persistence.
Is the permanganate in a high enough concentration to react with glycerin? Would give you a good idea of how well you did 💡😁👍
Or carefully react a few cc's with high concentration H2O2.
Being that you got some small crystals and a salt structure and being the potassium permangante is of a crystalline structure maybe you just didn’t either yield enough or the concentration you were using to boil and cool werent high enough.. but I think in fact you 100% got KMnO4 though!
@19:25 Should have shown before and after weights of the Mn metal chunks. By knowing how much mass was dissolved off the samples, you should be able to determine how much product you've made with stoichiometry.
Yep, definitely.
In fact, that was actually the plan, and I was preparing to do it as I set up the video, but then forgot to get an initial measurement before starting the cell. By the time I remembered, it was too late, so I had to scrap the idea. I'm still disappointed about forgetting it.
I want to revisit this project at some point anyway (using a better method for extracting permanganate crystals), in which I'll be sure to remember to measure the weights.
I haven't come across anyone that can make a permanganate with great success.
Can you use the pure manganese metal for the electrode in a chlorate cell?
That's an interesting idea. Maybe the surface would be oxidised to MnO2 under the chlorate cell conditions and simply run as a usable anode indefinitely. It seems a little too good to be true but definitely something worth investigating at some point.
Can you make HCl from NaCl (without acids) in next video?
Love your channel!
this channel is so underrated
What if you used a welder with carbon rods to melt your homemade manganese into a smol chunk
And make it 100% homemade permangante
If I were to make a bit more manganese it would definitely be feasible to melt it into a small electrode, but with the quantity I have it would be likely to simply oxidise away. I also don't have a welder at this stage and my furnace can't reach the right temperatures, so my efforts are currently going towards making the homemade manganese into a big chunk from the beginning.
Hey, at least it worked!! I suck at recrystallizing things too. Nilered does it so well.
I think maybe try purifying before recrystallizing.
Find something that KMnO4 is soluble in but the other things like KCO3 and KOH are insoluble in.
...actually, KMnO4 oxidizes everything but water, so the only solute you can use is water, so nevermind.
Well, even in water, the solubility of KCO3 and KMnO4 are very different.
solubility of KMnO4 = 76.5g/L @ 25 C, solubility of KOH = 970g/L @ 0C, KCO3 = 1103 g/L @ 20C. (numbers from wikipedia, tried to use something around 0C bc you will need cool the solution to lower solubility and speed up crystallization)
So you can boil the water to drive it off and make the KMnO4 supersaturated but all the KOH and KCO3 unsaturated.
But the high temperature might decompose the KOH. So let the water boil/evaporate at room temperature in a vacuum chamber.
Oh wait, but you also used NaHCO3, which has a much lower solubility of 69g/L @ 0C. (That's really close to 76.5g/L, so those purple things most likely were KMnO4 and NaHCO3). You could put it in the oven to make Na2CO3 (2NaHCO3 -> Na2CO3 + H2O + CO2), which has a slightly better solubility of 70g/L @ 0C. You could use NaOH, which has solubility 418g/L @ 0C.
I'm getting a sense that potassium just has higher solubility and you should use only potassium compounds as the anolyte.
Is it not fair of me to compare solubility in g/L? Should I compare the molarity at saturation instead? K is 22.989769u while Na is 22.989769u, so maybe K's bigger molar mass is why KOH has more g/moles. Well let's see: KOH has saturation molarity 970g/L / 56.1056g/mol = 17.3mol/L and NaOH has saturation molarity 418g/L / 39.997g/mol = 10.5mol/L. Either by molarity or g/L, KOH seems better.
Anyways, I'm wondering if here's anything easy to make and is more soluble than KCO3. Maybe
Cl2 + KOH makes KClO. Solubility 25% (temperature not given), so 25g KCLO/ 100g H2O = 25g / 100mL = 250g / 1L
Cl2 + NaOH makes NaClO. Solubility 293g/L @ 0C.
Nah, I think it's easier to just take some ashes and mix it with water, wait for the sludge to settle, pour the clear-ish liquid on the top through some coffee filters, and use that as anolyte. Or if you're concerned about purity then just buy KCO3. Or get KHCO3 (100.115g/mol) and stick it in the oven to turn it into KCO3(138.205g/mol) by (2KHCO3 -> K2CO3 + H2O + CO2). Because you should end with half the moles KCO3 as the moles of KHCO3 you started with, you should have 138.205(.5) / (100.115) = 69.0231% of the mass at the end.
Anyway, after that try the boiling in a vacuum chamber and putting it in the freezer for a couple hours. And then vacuum filtering out the aqueous KOH. Then pour some water and wash out any leftover KOH/KCO3 until u think it's pure. And then if you're still paranoid like Nigel, then do a melting point test and see if the melting point you get is 240 C +/- 10 degrees. Keep recrystallizing by adding water and boiling in vacuum chamber. until you get it right. You lose yield with each recrystallization bc some of the KMnO4 dissolves in the water each time, but purity increases.
Hope you get some pure KMnO4 if you do this again! :)
Also let me know if i got anything wrong bc im a noob at chem
Oh yeah, recrystallisation is pretty much my arch nemesis in chemistry. Every single time we've done it in lab classes, my product fails to crystallise. In the one class where I was actually able to crystallise something, it was completely the wrong product. I think I'm cursed or something lol.
As for your suggestions:
1) It would definitely be nice to purify the KMnO4 before crystallising, but as you've pointed out, there aren't really any solvents which will play nicely with the permanganate, so that's a little tricky.
2) You're right on the fact that KMnO4 is much less soluble than the K2CO3/KOH in the solution, so it should be easy to crystallise out. However, under basic conditions, permanganate disproportionates into manganate quite considerably, so it's near impossible to crystallise out our product without first pushing the solution towards a more neutral pH. This is why I used sodium bicarbonate (which ideally, would have acidified the solution into the ideal neutral region).
3) Boiling down the solution a little (along with neutralising the pH), and cooling to 0C is the general way to go for crystallising potassium permanganate, you're correct on that one too.
4) As for using other potassium salts, I'm afraid the electrolysis process only really works in highly basic conditions, which limits us to potassium/sodium carbonate and hydroxide (and in general, carbonates work better than hydroxides). The best choice of course, is K2CO3, since it gives the highest solubility, is easiest to neutralise, and is the most effective for the process anyway.
Sadly, as I stated earlier, the crystallisation has to be done in near-neutral conditions, which means we have to acidify it once we're done. In the future, I'll try acidifying the solution by bubbling carbon dioxide through it (based on numerous suggestions) since it won't add any excess ions to the solution that may interfere with the crystallisation.
5) Boiling the solution down with a vacuum chamber is definitely a good idea to avoid any thermal degradation, thanks! I'll see if I can put one together for next time.
I'll definitely be trying this reaction again (I'm actually planning on starting from manganese dioxide, which is much easier to get than Mn metal), so hopefully you can look forward to seeing some actual permanganate crystals at some stage.
Also, I definitely wouldn't call you a chemistry noob, you seem to have an excellent idea about what's going on here :)
listing text KCO3 error, potassium chlorate KClO3, help? I'm sorry!
very doable by just melting NaOH with MnO2
seems about 50g batches is the sweet spot for a camping propane burner
this forms manganate first up when can then be precipitated with barium salt and then be acidified (with HAc, not HCl- forms Cl2) to yield watersoluble barium permanganate, this can then be reacted with potassium sulfate to give barium sulfate and potassium permanganate
biggest issue in this is getting rid of the MnO2, because it clogs up filters and you cant see what is MnO2 and what isnt, its like being blindfolded
as a bonus the manganate has a blue-green color to it, and if you simply put that into water, once it comes plenty close to neutral pH it turns pink, for water purification just this will do fine
Neat article on making potassium permanganate by electrolysis that is cool.
Give this man a doctor title
What's the power supply you're using? If it's DIY, could you share some links?
I basically just use an old PC power supply hooked up to a dirt cheap buck converter from ebay. I have a video on setting up the PC power supply here:
https://youtu.be/ygvbdwl-0bM
(Beware, that video is pretty old now and is likely to be pretty bad)
The cheapest buck converter I could find (the one I'm using) was here: http://www.ebay.com.au/itm/192007593319
@Scrap Science thanks! Good to see I'm not the only one doing electrochemistry down under :)
Can you try the Synthesis of Formalin by electrolysis?
I'd prefer to steer clear of any volatile carcinogens at this stage I'm afraid. But that's definitely an idea for the future, doesn't look too difficult either so hopefully I'll get around to it eventually.
@Scrap Science I think it needs platinum electrodes but not sure at all.
There isn't any video on YouTube so you'd be the first one.
Super! Beatiful! Thank your very much!
Without seeing the date of the paper, I got a pretty good ballpark when you held up a page and I read a reference to Bakelite.
now all i need is manganese metal, the easiest way i can do is thermite reaction hope thisll work
Yep, if you've got the ability to set up a thermite reaction, that's pretty much the ideal first step, hope it goes well!
you can test it by adding glychirine on your yild when in catch fire it potassium permanganate... just charing idea...bro
is that a new boost converter?
Nah, same buck converter I've been using for a little while, it probably hasn't shown up all that often in the last few videos though. I upgraded from the stupid carboard box power supply a few months ago.
What is the cathaode in?
I would like to try ammonium carbonate, we need a permanganate that has a low solubility (even in cold solution). ammonium & silver permanganate. before I thought calcium chloride would have work for displacement reaction.
Feel free to give it a go, but I'd definitely be wary of using ammonium carbonate as the raw reaction electrolyte, since the ammonium ion is definitely not electrochemically inert.
It would probably be more efficient to use the potassium carbonate process and then use an ammonium (or silver) salt for a double displacement reaction, precipitating your permanganate.
Can potassium permanganate expire?
Maybe you could put them in a desiccator and get the desired results.
If you freeze the solution you could pull a vacuum on it to sublime the water?
Interesting possibility
I worked on the Mississippi River here in US and we had barges upon barges of Mg metal. Most of the battery companies buy all the stuff up. Maybe the initial carbon anode was driving the formation of MnO4. Batteries are after all MnO rxn w/ carbon.
I’m gonna look I used to have a ton of the Mn in the raw from the side of the barges.
How well does a clay pot work as a separator, compared to other methods, lambskin condoms, gelatin etc?
really good, doesnt react, it holds liquids but allows ions to pass, and no contamination
@Edward Tries To Science even over the course of days? I always figured since terracotta is porous, and water molecules can squeak through, it would be similar for other solvents, acids... etc
Yep, a clay pot seems to hold up incredibly well despite the oxidising strength of the permanganate, especially in this non-acidic environment (in acidic solution, it seems the pots are somewhat less inert). Any kind of organic based separators would quickly be destroyed by the permanganate I'd imagine. It does (very slowly) let the solutions seep through the barrier but due to the electrostatic attraction of the ions to their respective electrodes (for example, permanganate is attracted to the anode), this effect is conveniently minimised.
There are other options for a separator too, porous alumina and maybe some kind of fibreglass matting would likely perform even better than a clay pot, but given how cheap the pots are, how large their surface area is and how well they work, I think they're pretty much ideal.
Should have used the titration station that you made in that old video I reckon
That's very true. If only I had it with me. Might have to do some testing first to see whether permanganate will stain the acrylic though
Can I use maganese plated on aluminium ,as an anode ??? Can I use KOH or NaOH instead of carbonates of potassium & sodium??
Metallic aluminium can't be made by aqueous electrolysis, even with a diaphragm. The reduction potential is just too low.
Making aluminium metal is ridiculously hard. You either need to reduce a molten aluminium salt with an alkali metal (like potassium or lithium) at high temperature and in an oxygen-free environment, or electrolyse a molten mix of aluminium oxide and cryolite at 1000C. You'll at least need a furnace (and probably a lot of other equipment) to do either of these things.
@Scrap Science okay.Can I use aluminium foil instead of powder for thermite ?
I'm afraid aluminium foil has nowhere near enough surface area for a thermite reaction. Powder is the only viable option here.
And yep, I certainly have seen that video, it's very cool stuff. Sadly, zinc is nowhere near as reactive as aluminium, so if you're thinking of using it for a thermite reaction instead of aluminium, it almost definitely won't get hot enough for a sustained reaction.
@Scrap Science Thanks mate.
Huh, I thought there would be much more MnO2 junk in there.
My thoughts exactly. I did end up filtering the solution after extracting it from the cell and it turned out that there was a gram or so of MnO2 (or something?) that had formed. Still much less than I was expecting though.
@Scrap Science i guess that's mainly from the time when your anode compartment got too acidic / depleted of potassium, before you transfer anything solution back from the cathode
Can’t permanganate be sublimated?
I'm afraid not. It decomposes well before that can occur.
@Scrap Science I realized I was thinking of iodine 😋 at least I got the color right
Why don't you let it stand in a dry room for 6 weeks and see what you get? 2 months might be better.
I didn't have the time in this case, but when I give it another go, I might need to try this, thanks.
Isn’t it easier to buy KMNO4 than manganese? Lol
Yep, it definitely is.
However, the ultimate goal with this process is to produce permanganate from MnO2 (which is much more available than both permanganate and manganese metal). In future videos, I'll first be making the manganese from the oxide, and then performing this process to make permanganate.
Missed ya :3
Daniel Matthews - 2020-11-18
This paper? https://libgen.lc/scimag/ads.php?doi=10.1021/ie50141a012 and would tracking the mass loss in your manganese electrode, next time, be informative?
Scrap Science - 2020-11-18
@elektronik zımbırtılar Good idea, it should also show up in the description now too
Telectronics - 2020-11-18
@Scrap Science Yes I don´t know any other video making permanganates with electricity. Love your results and don´t be sad about the crystals I have seen a lot people who could not get crystals from it. Seems like it´s not an easy task for me. Maybe you have to oversaturate it with the production of a lot more over the time and just filter it.
Yehia Ali - 2021-09-28
Hey man I'm sorry but if you have a pdf or such of the paper can you send it to me? The link no longer works.
Yehia Ali - 2021-09-28
@Daniel Matthews thanks bro