Anyone know what this inorganic reaction was?

Question

As a kid messing around with some chemicals many years ago, I mixed Potassium Permanganate , Sodium Bicarbonate, and maybe a bit of water in a test tube. Nothing happened for a while, then suddenly the test tube got so hot I had to drop it, while a bubbling frothing black mess boiled out of the tube.

What was the mystery reaction ?

Answer 1

ask GLAXO SMITH KLINE they re sure to know!!!!!they poison us with most if not all the medicines they produce.......

Answer 2

You heated it up over a Bunsen burner?

Answer 3

KMnO4 + NaHCO3 --> ???

The "decomposition" of permanganate ion into Mn2+ and oxygen gas is catalyzed with Mn2+.  That means the reaction is self-catalyzing.  I use this every year to look at reaction rates and redox reactions when my students study the reaction between H2O2 and KMnO4.

It's quite possible that there may have been a "third party"in the test tube that caused the reduction of manganese (VII) in the permanganate ion to Mn2+.  Once that happened then the further reduction of MnO4- was immediate and fast, as well as exothermic.  

The frothy stuff was due to the production of oxygen gas and the black stuff was actually a very dark purple due to the fact that KMnO4 is a very dark (almost black) purple, and much of  the KMnO4 hadn't had an opportunity to react.

The bicarbonate ion may not have had much to do with it, although at relatively low temperatures it will decompose to produce CO2, perhaps adding to the froth.

We may never know what reacted with the MnO4- ion to reduce the manganese.  I'm pretty sure it wasn't sodium bicarbonate.  It was just along for the ride, and maybe contributed some CO2.  There may have been some other contaminant in the test tube in a small enough quantity that it took a while for the critical amount of Mn2+ to form.

That's what happens in my H2O2 / KMnO4 reaction that I use for an AP chemistry research project.  The solution stays dark  purple for a while (up to a minute or more) and then suddenly turns colorless with the evolution of oxygen gas.  It takes a while for the H2O2 to reduce the Mn to +2, and then boom.  Well, not a boom, but a fast reaction with lots of ooohs and aaahs.