PowerLabs Sodium Peroxide
Deflagrations

Introduction:

Sodium Peroxide is said to "ignite and/or explode in
contact with organic matter or readily oxidizable substances" (Merck Index
12th ed.). The commercial product, 90 - 95% pure
Na2O2, has a variety of very important uses as a
bleach and as a CO2 => O2 converter in
submarines, diving bells, air purifiers, etc. It is one of the most
expensive reagents stored by PowerLabs, more expensive then Silver Nitrate
for example (over one dollar/gram), but the prospect of watching something
"ignite or explode in contact" was just too tempting to pass
on...

Materials:

A 25 gram bottle of Sodium Peroxide
Analytical Grade (96%) was used up in a series of experiments, some of
which are reported here.
The beaker used for this experiment was
a Schott Duran beaker, tougher than Pyrex. Other reagents used are in
Bold on the paragraphs below:

Procedures:

NOTE: The procedures described below are
EXTREMELY hazardous and should NEVER be attempted. These experiments are
outlined for informational purposes ONLY.
Sodium Peroxide decomposes very quickly
in water as it first forms concentrated Hydrogen Peroxide and Sodium
Hydroxide and then the H2O2 is decomposed by the
high PH of the caustic solution generating large amounts of Oxygen gas.
Calcium Carbide is also decomposed in water, forming Calcium
Carbonate and Acetylene Gas... Acetylene Gas combusts explosively in a
pure Oxygen atmosphere. It also decomposes spontaneously above 15PSI. A
small sample of Sodium Peroxide was first mixed with Calcium carbide and
water was added. A flame was held above the reading mixture and this
produced a roaring, exploding oxy-acetylene flame. A second sample was
remotely mixed inside a corked flask and this gave rise to a violent
explosion after a brief delay during which pressure built
up.
Secondly a simple deflagrant was attempted, this one a
modified flash powder mixture employing Magnesium powder, Sulfur and
Sodium peroxide as the oxidizer. The first problem with using
Na2O2 as a solid oxidizer is that it comes in the
form of spheres maybe 1mm in diameter; these have a relatively large
surface area which translates into a slow decomposition rate and thus poor
fuel/oxygen balance and slow combustion rates for the deflagrant.
Pulverizing the peroxide proved very difficult as the spheres are very
tough. This hygroscopic, water decomposed chemical will be rendered inert
much quicker in that form. A finer form was obtained after much work with
a mortar and pestle. This was added to the solid fuels, and mixing was
started by rolling a small amount in the middle of a sheet of paper.
Within seconds the material became clumped and ignited, deflagrating very
violently and burning the work table it was being mixed over. Sodium
Peroxide is most certainly not a good solid fuel candidate for
deflagrants!
Mixing Sodium Peroxide with warm Ethylene
Glycol resulted in a violent explosion and ensuing fireball that
splattered burning EG everywhere.

The "classic" Sodium
Peroxide demo is to pour some sodium peroxide on top of a few sheets of
paper and drop water on it. As the water decomposes the
Na2O2 Oxygen is produced. The
Na2O2 also reacts directly with the paper oxidizing
it very rapidly. The heat produced ignites the paper which burns in a pure
oxygen atmosphere, producing a very violent, hot, bright flame with the
characteristic Sodium yellow spectra. In this particular demo one teaspoon
of Na2O2 was used for 4 sheets of toilet paper
stuffed in a glass beaker.

Results:

Just a few seconds after the water soaks through the
paper into the sodium peroxide the beaker spontaneously erupts into a
violent, roaring/crackling flame that reaches over a few feet in height
and is hot enough to quickly melt through the bottom of the beaker. I
suspect that part of the reason why the beaker melted must have been due
to chemical attack from molten sodium peroxide at 675C, as evidenced by
severe corrosion on the inside after the flame extinguished itself. The
beaker becomes so hot during this experiment that the table it is sitting
on spontaneously ignites also!
Click on the image to download the
4.4MB, .mpg Video of the reaction.

Relevant
Links:

PowerLabs
Potassium Permanganate Hypergol; another fine example of
hypergolic reactions!
PowerLabs
Deflagrants overview; examples of similar reactions to the one
on this page.

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People have visited this page since
09/04/03.
Last updated 30/01/04

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