Manganese Heptoxide Synthesis

Manganese heptoxide (Mn2O7) is the anhydride of permanganic acid. It is an extremely strong oxidizer and reacts violently when in contact with organic materials (including people!). Synthesis of this substance is not recommended, as it is very dangerous. I see it as mainly a novelty with no particularly useful purpose. Apparently it’s used in school science experiments and I just made it because I find it interesting.

The actual synthesis is quite simple, requiring only potassium permanganate (KMnO4) and sulfuric acid (H2SO4). The only step here is adding the KMnO4 to the acid. I did this outside. The KMnO4 and acid react and Mn2O7 is formed because of the dehydrating power of the acid. It can be seen as an oily green liquid. It's a bit hard to see in the picture but it's there (the acid was originally light red in colour).



The next part was of course ignition. The edge of a tissue was dipped into the Mn2O7 and it made a popping sound, spraying some liquid and releasing some gaseous brown MnO2. The tissue was then placed on top at which point it caught fire and burned, producing more MnO2.



While it's not very practical, it is still pretty cool. But I would advise against making this, and I have heard of quite a few accidents due to Mn2O7.

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