Physics Photo of the Week
January
30, 2009
Thermite
Chemistry
professor Dr. Steven Cartier recently demonstrated a rather violent
Thermite reaction. The reaction consists of common Aluminum metal
and Fe2O3 (common Iron oxide). This mixture
of Al and Iron oxide is "unstable". The bonds between
the Aluminum and the Oxygen are stronger than the
bonds between the Iron and Oxygen. This means that it
can
achieve a state of lower energy by breaking the Iron-Oxygen bonds and
forming Aluminum-Oxygen bonds instead.
However, a large "activation energy" is required in
order to break the Iron-Oxygen bonds to start this reaction. The
materials need to be
pre-heated so the mixture has enough thermal energy to break the
Iron-Oxygen bonds. Once this reaction 
is
started the smaller energy state of the final products emits a
tremendous amount of heat. The smaller image at right shows Dr.
Cartier lifting the resultant hot incandescent Iron metal out of the
bucket of sand.
In order to initiate this process, Potassium Permanganate (KMnO4)
is mixed with the Al metal and Iron Oxide in a clay flower pot.
The Potassium Permanganate is unstable and easily oxidizes some
glycerol that is carefully poured onto the mixture. The
Permanganate glycerol reaction produces enough heat to initiate
the main Al - Iron Oxide reaction (see the photo at left below.
Finally a video clip is shown below right. The reaction is
started in the clay flower pot. As the molten Iron is formed, it
drips through the hole in the bottom of the pot into the sand bucket
below. In the final frames, the sand bucket as well as the clay
pot are both glowing red from the very high temperature.
Physics
Photo of the
Week is
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature an interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to dcollins@warren-wilson.edu.
All photos and discussions are copyright by Donald
Collins or by the person credited for the photo and/or
discussion. These photos and discussions may be used for private
individual use or educational use. Any commercial use without
written permission of the photoprovider is forbidden.
Click
here to see the Physics Photo
of
the Week Archive.
Observers are invited to submit
digital photos to:
