Sciencemadness Discussion Board

experiment?

heksogen - 10-5-2004 at 01:21

Some time ago i have seen a "chemist show" made by some students. One of their experiments was putting some KMnO4 to a flask containing some 30%H2O2 solution. The mixture imidiately started fuming. Once I also made this experiment. The result was the same and I noticed the flask was very, very hot. What was the reaction???

Saerynide - 10-5-2004 at 01:39

Quote:
Originally posted by madscientist
KMnO4 oxidizes H2O2 readily, causing both to decompose... I have tried adding two or three grains of KMnO4 to a test tube 1/4 of the way filled with 27.5% H2O2, and the result was a violent, hot, oxygen gas / steam forming reaction. All that was left was some very hot water, and Mn3O4 (I believe that's what the dark brown precipitate was).

hodges - 10-5-2004 at 17:48

You can get a similar decomposition reaction with other catalysts and hydrogen peroxide. For example, potassium iodide. The decomposition of hydrogen peroxide liberates heat, and the reaction also occurs faster at high temperatures. Like a fire, it is self-sustaining. I believe some model rockets used or still used plain hydrogen peroxide as fuel with a catalyst. The steam produced by the heat of decomposition provides the necessary thrust.

axehandle - 10-5-2004 at 17:52

Quote:

I believe some model rockets used or still used plain hydrogen peroxide as fuel with a catalyst. The steam produced by the heat of decomposition provides the necessary thrust.

I'd wish. You would have to turn to NASA for data on that.

vulture - 11-5-2004 at 04:37

It's possible and has been done before.

>60% H2O2 (this is the tough part) is being dripped/pumped through a silver mesh or a MnO2 contact bed.

The produced oxygen can be used to burn a hydrocarbon in an afterburner stage.

[Edited on 11-5-2004 by vulture]

Tacho - 11-5-2004 at 11:54

Quote:
Originally posted by vulture
It's possible and has been done before.

>60% H2O2 (this is the tough part) is being dripped/pumped through a silver mesh or a MnO2 contact bed.

The produced oxygen can be used to burn a hydrocarbon in an afterburner stage.

[Edited on 11-5-2004 by vulture]


Can I use MnO2 over and over again or does it get consumed somehow?

I'm thinking of small beads made of MnO2 and some binder as a permanent catalyst.

vulture - 11-5-2004 at 13:12

Your MnO2 won't be consumed as it acts as a catalyst.

Your binder must be H2O2 resistant.

[Edited on 11-5-2004 by vulture]