Has anybody managed to grow a single crystal of KMnO4? Couldn't find much on the internet, sorry if this is repost, I am new here. LearnedAmateur - 18-12-2017 at 12:18
Welcome to the forums, AFAIK you can't create a crystal of KMnO4 from aqueous solution because it will decompose. I made a Christmas tree decoration
using it once, a layer of green KNaMnO4 solution (addition of NaOH) on top of the purple solution. After a few days it had completely broken down
leaving a clear solution and brown-black precipitate of MnO2.unionised - 18-12-2017 at 12:36
...AFAIK you can't create a crystal of KMnO4 from aqueous solution because it will decompose.
When you buy permanganate, what do you think it was crystallised from?Micha - 18-12-2017 at 12:47
Well, what if you would paint them with transparent nail polish? It decomposes in water solutions to MnO2, and to decompose it to K2MnO4 you would
need some heat , alkali solution. I am anyway going to try it, I just want to know if someone tried it yet.Micha - 18-12-2017 at 12:49
Well, as I think of it now, as you would wait for bigger crystals to appear, it would decompose in water solution into MnO2LearnedAmateur - 18-12-2017 at 14:49
...AFAIK you can't create a crystal of KMnO4 from aqueous solution because it will decompose.
When you buy permanganate, what do you think it was crystallised from?
I'd always thought that water was removed during the synthesis from manganate, generating the solid that way. Like I said, in my experience it is
unstable in aqueous solution, at least at low concentrations anyway (low enough to be able to see through without shining a light).
All the permanganate products I've seen either come as a coarse powder, which is how I got it, or small crystals. I guess it could be crashed out of a
hot solution upon cooling as opposed to the usual method of crystal growth, letting the water evaporate over a period of days/weeks? I've never come
across a single crystal larger than a few millimetres, have you? I'd like to be proven wrong, as it would certainly be a cool crystal to own!
[Edited on 18-12-2017 by LearnedAmateur]mayko - 18-12-2017 at 21:00
I got these trying to purify some grungy eBay koi treatmen; there might have been some minor decomp but the main thing I learned was that filter paper
doesn't stand up to hot, concentrated permanganate
unionised - 18-12-2017 at 23:25
Potassium salts- like permanganate and dichromate- are often preferred over the sodium for laboratory use even though they are more expensive, because
they generally have steeper solubility curves and are therefore easier to purify by recrystallisation
