----- Original Message -----From: Nail, JohnSent: Monday, January 25, 2010 9:12 AMSubject: 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.
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
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:
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!
Lab Safety Specialist
Stony Brook University
EH&S Web site: http://www.stonybrook.edu/ehs/lab/
ecovering; cause of blast uncertain
Published: Thursday, January 21, 2010
By JAY BRAMAN JR.
BOICEVILLE - The explosion on Tuesday that injured an
chemistry teacher and seven of his students came as a surprise to everyone, but probably no one more than the longtime teacher himself. Onteora High School
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, r
ecovering 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
and Benedictine hospitals, primarily for minor cuts, and released. Kingston
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 d
ecompose 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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