[neact] FW: [DCHAS-L] Possible cause for this HS chem accident
- From: Stephen Stepenuck <sstepenuck@xxxxxxxxx>
- To: "neact@xxxxxxxxxxxxx" <neact@xxxxxxxxxxxxx>
- Date: Mon, 25 Jan 2010 22:07:04 -0500
And yet another contribution, from the DCHAS list.
sjs
------ Forwarded Message
From: DAVID KATZ <dakatz45@xxxxxxx>
Reply-To: DCHAS-L Discussion List <DCHAS-L@xxxxxxxxxxxx>
Date: Mon, 25 Jan 2010 19:38:40 -0700
To: <DCHAS-L@xxxxxxxxxxxx>
Subject: Re: [DCHAS-L] Possible cause for this HS chem accident
Years ago, we stopped using potassium chlorate to prepare oxygen in the
classroom. It was not safe to assume that students had properly cleaned and
dried their test tubes without using any paper towels or other material
that could be easily oxidized. There were numerous reports explosions,
although I never experienced anything more that a small spark in the
reaction test tube.
I have personally done the molten potassium chlorate experiment in the past,
but I always used a small quantity of potassium chlorate, a small piece of a
wood splint and a heavy wall ignition tube. The reaction was always
performed behind a safety shield. Students were moved to at least 10 yards
away. I did stop performing that experiment in the early-1980's, along with
many fire, smoke, and small explosion-type reactions. The main reason was
that I was doing a lot of outreach to schools and public groups and was
concerned that students' and the public's perception of chemistry as always
"blowing things up".
I'm concerned that the report states that the teacher dropped a "stick of
gum" into the test tube and that the district superintendent stated "it is a
standard high school chemistry experiment and that Bucher executed each of
its steps properly on Wednesday". I think an attorney will have a very
different view of the matter.
Whatever the reason for the explosion, this incident is an excellent reason
that all science teachers must have adequate safety training as part of
their college education, the correct safety equipment (such as safety
shields, proper vessels suitable for demonstrations and experiments, etc.)
and we should be considering restricting certain demonstrations rather than
just listing chemicals that can be hazardous.
For those of you who do go out to schools or provide workshops to teach
proper safety. Thank you! Keep up the good work. Maybe we can stop more
of these incidents from happening.
David
_________________________________________________________________________
David A. Katz
Chemist, Educator, Expert Demonstrator, Science Communicator, and
Consultant
Programs and workshops for teachers, schools, museums, and the public
133 N. Desert Stream Dr. * Tucson, AZ 85745-2277 * USA
voice/fax: (520) 624-2207 * email: dakatz45@xxxxxxx
Visit my web site: http://www.chymist.com
_________________________________________________________________________
>
> ----- Original Message -----
>
> From: Nail, John <mailto:jnail@xxxxxxxx>
>
> To: DCHAS-L@xxxxxxxxxxxx
>
> Sent: Monday, January 25, 2010 9:12 AM
>
> Subject: Re: [DCHAS-L] Possible cause for this HS chem accident
>
>
>
>
>
> 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@xxxxxxxxxxxx] On Behalf Of
> Kim Auletta
> Sent: Monday, January 25, 2010 8:32 AM
> To: DCHAS-L@xxxxxxxxxxxx
> 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
> <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
> <javascript:catLink('','','','2337253')> ), VWR, Flinn (cat. #SE225
> <http://www.flinnsci.com/store/Scripts/prodView.asp?idproduct=21420> ) 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@xxxxxxxxxxxxxxxxxxx
> 631-632-3032
> EH&S Web site: http://www.stonybrook.edu/ehs/lab/
> <http://www.stonybrook.edu/ehs/lab/>
>
> _____________________________________________________________________
> New York
>
> http://www.dailyfreeman.com/articles/2010/01/21/news/doc4b57e5a7a5748273921860
> .txt
> <http://www.dailyfreeman.com/articles/2010/01/21/news/doc4b57e5a7a574827392186
> 0.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.
------ End of Forwarded Message
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