PowerLabs Potassium Permanganate
Hypergols

Introduction:

Due to their spontaneous nature, hypergolic reactions
can be amongst some of the most interesting to watch in chemistry.
Although there are exceptions to this, in general if two substances are
reactive enough ignite spontaneously on contact chances are that the
reaction will also proceed at a very high rate. Fluorine/metal powders,
Alkali metals/water, Fuming Nitric Acid/Fuels, and others will all explode
on contact due to the extremely high reaction rate and heat produced
during the reaction. This classic high school chemistry demo shows one
particularly interesting (although not very violent) hypergolic reaction,
and also demonstrates that not all self initiating chemical reactions
happen spontaneously:

Materials:

Reactants:

Materials:

Potassium Permanganate
(KMnO4(s))

Hourglass

Ethylene Glycol
(C2H6O2(l))

Eyedropper

Propylene Glycol
(C3H8O2(l))

Glycerin (Glycerol,
C3H8O3(l))

Procedures:

On the topic of potassium permanganate, it should
also be mentioned that the reaction with hydrogen peroxide, particularly
at high concentrations (50%+), is EXTREMELY violent and has been used to
power turbopumps and rocket engines as the KMnO4 decomposes
into O2 and Mn3O4, which then goes on to
decompose the H2O2 into O2 and
H2O, with the evolution of enough heat to turn the entire batch
into a blast of steam. PowerLabs hopes to develop one such engine some
day, should time and machining facilities permit.
For this demo
a teaspoon of potassium permanganate (a black/purple powder) oxidizer is
placed in the middle of an hourglass with a small depression on it and a
few drops of a liquid fuel are placed in the depression.

Results:

Depending on the ambient temperature, the water
content of the fuel, the amounts used, the degree of mixing and the grain
size of the fuel the reaction may take place any time between instantly or
after several minutes. With coarse grains and low ambient temperatures
(this reaction is VERY temperature dependant) the reaction may refuse to
take place at all until warmed up. Ethylene Glycol (caution: this is a
poison) is the fastest reagent, igniting on the tested samples within 10 -
20 seconds. Glycerin takes longer, at 20 - 30 seconds. Propylene Glycol
took the longest, averaging over 40 seconds prior to ignition. Once the
reaction starts some smoke develops and a purple flame (emission typical
of excited potassium ions) erupts with the evolution of some smoke.
Clicking the image will download a video showing Glycerin
reacting.
3.2MB, 25seconds, .mpg.

Relevant
Links:

Sodium
Peroxide Deflagration; another fine example of hypergolic
reactions!
PowerLabs
Deflagrants overview; examples of similar reactions to the one
on this page.

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09/04/03.
Last updated 30/01/04

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