Everyone who has gone through High School Chemistry has seen the
"Sodium In Water" experiment. First the periodic table is explained, and
the reactivity of the Alkaline and Alkaline Earth Metals is talked about,
along with their counterparts; the Halogens. A small chunk of Barium,
Magnesium, Calcium, Lithium, Sodium and Potassium is than dropped in
water, one after the other, and their reactivity is observed as the metals
first bubble, than sizzle, melt, and finally catch fire, as is the case of
Potassium. The luckier ones amongst us may also have watched the video
"Periodic Table" (I think that is the title. Its one where some idiot
sings the names of all the elements in the end) where Rubidium and Cesium
are also dropped, with vastly more impressive results.
That they don't tell you in High School though, is what would happen if
you were to take one of the more reactive metals, such as Sodium, and drop
it into water at very large quantities.
PowerLabs, always at the forefront of science, brings you the answer to
that age old question.
One reasonably sized chunk of sodium, and an outdoors water puddle
surrounded by nothing valuable or flammable.
Here is a typical Sodium sample that was used for the
experiments. Sodium was obtained at the price of 24 dollars per 25 grams at
the time. The sample pictured weights under 10 grams (density of Sodium =
Sodium reacts with water to form Sodium Hydroxide and Hydrogen
Gas. The reaction produces a lot of heat, which is sufficient to
melt the metal (MP: 96C) if enough of it is used. If the reaction is
scaled up further, the molten metal may start to boil, which is when
exciting things start to happen: The boiling metal breaks apart and
thus increases its surface area, speeding up the reaction rate. The
faster reaction produces more heat, which ignites the Hydrogen Gas
being produced, which leads to an explosion, which breaks up the
remaining liquid metal, which leads to an extremely rapid reaction
that results in so much heat that the metal catches fire. The final
explosion probably releases as much energy from combusting Hydrogen
as it does from burning sodium (2Na + O2 = 2NaO).
Pictures and videos:
The picture to the left shows the culminating point of
a video done outdoors during a storm. The sodium is seen first being removed
from the bottle, than thrown outside on a water puddle. The metal reacts
with water melting and boiling, and than a small explosion occurs which
sends up molten sodium drops into the air. As soon as the drops hits the
water puddle again a large explosion ensues, which sends sparks flying up
into the air and leaves a large smoke cloud behind. Very good video, a must
see. Clicking on the picture will download the video (3.5MB, MPG).
This video shows a larger chunk of sodium being thrown in the same parking
lot at night. The fence seeing in the background is about 10 meters high,
and the sparks are flying above it (286Kb, MPG).
Other Experiments (Not documented):
1- Sugar Cube sized chunk of Sodium dropped into a half filled Cola Can:
The can explodes and is ripped to shreads.
2- Sodium Dropped into 68% Nitric Acid: The sodium reacts violently, forming
a intense flame as the Hydrogen combusts with the NO2 / N2O4 formed by the
decomposing acid. After a few seconds the reaction escalates into an
explosion and acid is sprayed out of the reaction vessel. This is definitely
one I am not repeating!
Comments welcome: Mail me, and
tell me what you think!
People have visited this page since 18/11/02.