Date: Mon, 25 Jan 2010 19:38:40 -0700
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From: DAVID KATZ <dakatz45**At_Symbol_Here**MSN.COM>
Subject: Re: Possible cause for this HS chem accident
In-Reply-To: <OFEA891D02.B8ED993D-ON852576B6.004E4D30-852576B6.004FD2F9**At_Symbol_Here**>

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 A. Katz             
  Chemist, Educator, Expert Demonstrator, Science Communicator, and Consultant  
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  133 N. Desert Stream Dr. * Tucson, AZ 85745-2277 *  USA
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----- Original Message -----
From: Nail, John
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
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**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 ( specifically lists tartaric acid as an incompatible material:

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
Stony Brook University
EH&S Web site:

___________________________________________________________________ __
New York 48273921860.txt

Teacher recovering; cause of blast uncertain
Published: Thursday, January 21, 2010


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.

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