Sciencemadness Discussion Board - Permanganates

Permanganates

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Omniquist - 15-2-2018 at 22:25

Given the recent CPSC(assholes) victory against FireFox, I'm sure that any convenient
method will be appreciated. KMnO4 sales by pyro suppliers are now limited to 1 LB a
year. There's still some OTC sources for now but we don't know how long that'll last.

So dont go to a pyro supplier. I got mine at a water depot, 5 lbs for about 45$. Farmers use it to take iron out of well water for cattle. They didnt even give me a second glance when I bought it.

I got a five pound bag from ace hardware. They don't have it in the store, at least in the state (USA, sorry everybody else not able to buy in ur country) of maryland. They put an order in for me and called about five days to a week later, it cost 39 us$ and needed my ID.
As for the calcium or sodium hypochlorite bleach I used with an old, likely dead d cell battery I had found. I didn't follow strict chemistry, but behaved like a cook, not measuring the hypochlorite bc I don't recall an exact measurement read. What ended up happening makes me concur with whoever said using hypochlorite is messy and difficult. I used about a half cup of standard bleach liquid (generic chlorox) and the crushed dark solid from the battery along with, again (and I DO know better, laziness was the lesson and why to avoid it) along with about a tablespoon of lye, which I found out may have been my problem. I boiled in measuring cup on hot plate, which took forever. Finally once it started it began to foam, bad. I took it off heat immediately and stirred like as if to make whipped cream or soufflé, and somehow succeeded in not spilling any. Thanks to whoever said that the majority of battery electrolyte is carbon bc my filter proved this. I used the top of a plastic water bottle, cut in half, as a funnel and a cotton ball stuffed in the mouth as a preliminary filter. No way was I using anything remotely dear to me for this project. What came thru was a pine green and aquatic blue homegenous transparent fluid, recognized as the manganate it was. However.... Pouring this same solution, this pretty green stuff which I meant to acidify promptly had turned into a dilute champagne/urine liquid, again transparent. Guessing it was mncl. I'll let u guys know how it goes using kno3, the battery innards but DRY, using the method employed by nurdrage, placing this mix in a container to be lit from underneath by torch. lowering ph with bicarbonate of potassium as sodium apparently eats the product before extraction. In hindsight I never have heard of sodium permanganate. Hmm.. I'll utfse. Thanks for your time and wisdom. I learn everyday from everyone on here.

CobaltChloride - 4-3-2018 at 07:04

Quote: Originally posted by DerAlte

Forget K peroxydisulphate unless you have it on the shelf. Even then, it's marginal due to H2O2 formation.

DerAlte

I know this thread is pretty old, but could somebody tell me if they have tried the S2O8 2- oxidation? I can't seem to find its potential in alkaline solution. I would really like to know as Na2S2O8 is really cheap in my country, and so are 6% SO2 solution (to reduce MnO2 to soluble MnSO4) and KOH.

[Edited on 4-3-2018 by CobaltChloride]

clearly_not_atara - 9-1-2019 at 13:00

Quote: Originally posted by Romain

Update: The crystals that formed from the evaporated anolyte are highly impure as evidenced by the presence of white crystals and brown crud among the needles of KMnO4. The crystals were dissolved in a small amount of water and the solution was heated up to boiling. It was filtered while hot on a preheated filter funnel (to remove MnO2, again). The filtrate yielded 0.37 g of small (and pure) needles of KMnO4 upon cooling.

(More KMnO4 could be extracted from the anolyte, but this run was just to prove that the method works and I didn't try to be particularly efficient in the extraction.)

The product was tested by adding a few drops of conc. H2SO4 to a crystal to form Mn2O7 and the reaction with ethanol was as expected: it ignited!

After everyone argued about it for ten years, Romain walked up, casually solved the problem on the first try, posted a picture, and nobody even noticed.

I have to say, I find the use of KCl as the potassium source to be perplexing. Chloride is obviously susceptible to oxidation by permanganate. There are a couple of other possibilities, but the most obvious IMHO is potassium acetate.

Properties of pure permanganic acid

chornedsnorkack - 20-2-2019 at 02:49

It can be and has been made. Stable and easily isolated.
Published in Jacs, in 1969. Sadly, only first page is visible. Has anyone reached the next pages?
https://pubs.acs.org/doi/abs/10.1021/ja01050a058
To summarize the procedure:

Produced pure dilute permanganic acid from stoichiometric amounts of dilute Ba(MnO₄)₂ and dilute H₂SO₄, and centrifugating the BaSO₄ precipitate - about 0,3 M (3,6 %) permanganic acid
Froze the acid. Did it by putting it into -75 Celsius acetone/dry ice bath and rotating, about 240 ml acid in 500 ml glass flask
Vacuum evaporation. Their vacuum pump was capable of 0,001 Torr, and they sent the vapours through two traps of -75 Celsius acetone/dry ice and -193 Celsius liquid nitrogen. At first, pure ice was sublimed
At some point, pink appeared in the trap - then the -75 Celsius trap was changed to collect separate fraction
Finally, volatile fractions had left. The residue was found to be quite hygroscopic, solid, soluble - and pure HMnO₄

So, what is on the next page/s?
Did they find out what happens when frozen solid HMnO₄ is warmed above +1 Celsius? At what temperature does it melt? Congruently or incongruently?
Has anyone repeated their synthesis?

ref

HeYBrO - 27-3-2020 at 01:03

[Edited on 27-3-2020 by HeYBrO]

[Edited on 27-3-2020 by HeYBrO]

Attachment: pg2forguy.pdf (279kB)
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Bedlasky - 14-12-2020 at 21:13

I found on youtube this really interesting reaction - chemiluminecense from reaction between KMnO4 and Na[BH4]:

https://www.youtube.com/watch?v=gSP_953YMF8&t=187s

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