Sciencemadness Discussion Board

Crystallization of KMnO4

sternman318 - 10-6-2011 at 11:25

Are there any viable routes to crystallizing potassium permanganate? It seems that it is so unstable that most routes would end up decomposing it. The solution is pure, and of about 2% concentration( w/v, i believe)

Mixell - 10-6-2011 at 12:26

It decomposes at 240 C, I think you can evaporate the water slowly, without any decomposition. Just put in on the hotplate and turn the heat just before the point where bubbles appeared, let it sit for a few hours, slowly turning the heat down as more and more water evaporates.

Mixell - 10-6-2011 at 12:42

Or if you don't want to evaporate all the way through, leave a concentrated solution and freeze it, crystals should form (KMnO4 is about 15 times more soluble at 100C than at 0C).

redox - 15-6-2011 at 03:10

KMnO4 is not very stable in water, and your crystallized product will contain small amounts of MnO2 and KOH.