If I react KMnO4 with glycerin, the residue remaining will be mostly Mn2O3, correct? Like this...

 

14 KMnO4 + 4 C3H8O3 ---> 7 K2CO3 + 7 Mn2O3 + 5 CO2 + 16 H2O

 

My question is, could I then replace the Mn with Mg to get Mn metal? I think this would work. This would be a type of thermite, correct?

 

Mn2O3 + 3 Mg ---> 3 MgO + 2 Mn

 

I'm interested in taking the classic KMnO4 + glycerin experiment further. That's why I'm thinking about doing this.

you could do a thermite to get manganese, yes, but i wouldnt suggest you use Mg, as it's pretty expensive. Al works a charm

Good idea, thanks budullewraagh. Al is much cheaper. I didn't even think of it because I kind of have a fixation on magnesium and it's the first thing that popped into my mind.

you must make sure that the heat of the reaction dosnt exceed the boiling point of Mn. If it does, it will explode sending molten globs of Mn everywhere.

you could also mix it with an acid to make the corresponding salt and then use electrolysis to isolate it, you`de get a far cleaner product