Another
possibility
is that the demo involved molten potassium chlorate - also known as
the gummy
bear immolation demonstration. A small piece of candy, such as a gummy
bear is
dropped into molten potassium chlorate - a dramatic red flame (that
can shoot
out several inches from the reaction) immediately is produced via the
sugar in
the candy reacting with the oxygen in the molten KClO4 and the flame
heating
the K+ ions. Afterwards, everything in the immediate area is covered
with KCl.
I've done this one several times in the past, but always in
evaporating
dishes, never out of a test tube. Nowadays, I would never do this in a
classroom.
From:
DCHAS-L Discussion List
[mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On
Behalf Of
Kim Auletta
Sent:
Monday, January 25, 2010 8:32 AM
To:
DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Possible
cause for
this HS chem accident
I think I have a possible cause for this HS
chemistry
class accident. I asked one of our researchers here who was a former
food
science chemist. She said that it if the teacher used the SOUR flavor,
they
set up an incompatible reaction.
Tartaric acid is
used in the
food industry to make the "sour" taste for gums and candy. The JT
Baker MSDS
for potassium chlorate (http://www.jtbaker.com/msds/englishhtml/P5620.htm)
specifically lists
tartaric acid as an incompatible material:
Incompatibilities:
Iodides, tartaric acid,
aluminum,
sulfuric acid, hypophosphite, powdered metals, organic matter and many
other
oxidizable substances.
It is also
possible that all
of the candy/gum wrapper was not removed and the caused a more
vigorous
reaction than anticipated.
This experiment,
which
appears to be common in HS chemistry classes, should have the
following safety
instructions included for all who demonstrate this
reaction:
1. Read the MSDS for all chemicals before
you use
them. Make sure to read more than 1 manufacturer's MSDS - not all
listed the
specific chemical incompatabilities.
2. Do not use the
SOUR flavor
for the candy.
3. Check all
glassware for
any nicks, scratches, etc. Do not use if present.
4. Use a
plexiglass or lexan shield between the students and the demonstration.
These shields can be purchased from Fisher
(cat.#
1429340), VWR,
Flinn (cat.
#SE225) or
other companies.
They are expensive, but can be made relatively cheaply - buy a large
sheet of
lexan or plexiglass 5 to 20 mm thick and ask the Tech Teacher to cut
it and
mount it on a metal base.
Remember that the
OSHA Lab
Standard requires that there are written protocols for all
experiments. These
protocols must include the safety requirements!
Kim Auletta
Lab
Safety
Specialist
EH&S
Stony Brook
University
kauletta**At_Symbol_Here**notes.cc.sunysb.edu
631-632-3032
EH&S
Web
site: http://www.stonybrook.edu/ehs/lab/
___________________________________________________________________
__
New
York
http://www.dailyfreeman.com/articles/2010/01/21/news/doc4b57e5a7a57
48273921860.txt
Teacher recovering; cause of blast
uncertain
Published:
Thursday,
January 21, 2010
By
JAY BRAMAN
JR.
Correspondent
BOICEVILLE - The explosion on Tuesday that
injured an
Onteora
High School
chemistry
teacher and seven of his students came as a surprise to everyone, but
probably
no one more than the longtime teacher
himself.
Donald Bucher was demonstrating an experiment
with the
chemical potassium chlorate when the explosion - which was strong
enough to
damage a window in the classroom - occurred. Onteora school district
Superintendent Leslie Ford said on Wednesday that Bucher had conducted
the
same experiment dozens of times before, without incident, and that the
cause
of the explosion remained a mystery.
Ford said Bucher was resting at home on
Wednesday,
recovering from his
injury, and
that an investigation of the incident will begin
shortly.
"We still
don't know
what happened," the superintendent said. "But we will debrief Mr.
Bucher when
he is well enough to return."
Ford said a small piece of glass punctured
Bucher's arm and
cut an artery. "He was bleeding quite a lot," she
said.
A reporter's
calls to
Bucher's home were not answered on
Wednesday.
The seven students who were injured, all
11th-graders, were
treated at Kingston and Benedictine hospitals,
primarily
for minor cuts, and released.
Ford said the explosion occurred when Bucher
dropped a
stick of gum into a test tube containing potassium chlorate, a
chemical used
in matches, explosives, gunpowder and
fireworks.
Ford said school district officials reviewed the
chemistry
class' lesson plan and concluded the experiment had been performed
safely by
Bucher in the past. She also said it is a standard high school
chemistry
experiment and that Bucher executed each of its steps properly on
Wednesday.
"The goal
of the
experiment was to determine the amount of oxygen in the potassium
chlorate,"
Ford said.
The
superintendent
said possible causes of the accident were a faulty test tube or the
chemical
itself being compromised.
All
the remaining potassium chlorate in the classroom was removed, bagged
locked
in a secure location elsewhere in the building by Michael O'Rourke of
the Risk
Management Department at Ulster BOCES, Ford
said.
O'Rourke said on Wednesday that the chemical will
be
disposed of properly and other chemicals in the school will be checked
for
problems.
According
to a Web
site co-maintained by the National Oceanic and Atmospheric
Administration,
potassium chlorate is a white crystalline solid. It is used in
matches,
explosives, gunpowder and fireworks; as a disinfectant; and as an
oxidizing
agent. It forms a flammable mixture with combustible materials, and
the
mixture can be explosive if combustible material is finely
divided.
Potassium
chlorate
can be ignited by friction, and contact with strong sulfuric acid may
cause
fires or explosions, according to the Web site. Also, it may
spontaneously
decompose and ignite when
mixed
with ammonium salts and may explode under prolonged exposure to heat
or
fire.
Ulster County
Emergency
Management Director Art Snyder appeared before the Onterora Board of
Education
during the body's regularly scheduled meeting Tuesday evening. He
outlined the
procedures for hazardous materials disposal, though Ford noted the
procedures
were not required in Tuesday's incident.
