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Previous by Date: Subject: Re: Laboratory/Chemical Storage Temperature Control Date: Mon, 25 Jan 2010 09:11:24 -0500 Author: "Yaeger, Mary Ann" |
Next by Date: Subject: Re: Possible cause for this HS chem accident Date: Mon, 25 Jan 2010 10:12:04 -0600 Author: "Nail, John" |
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/doc4b57e5a7a5748273921860.txt Teacher recovering; cause of blast uncertain Published: Thursday, January 21, 2010 By JAY BRAMAN JR. Correspondent BOICEVILLE Ñ 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 Ñ which was strong enough to damage a window in the classroom Ñ 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 donÕt 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 BucherÕs arm and cut an artery. "He was bleeding quite a lot," she said. A reporterÕs calls to BucherÕs 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 classÕ 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 OÕRourke of the Risk Management Department at Ulster BOCES, Ford said. OÕRourke 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 bodyÕs regularly scheduled meeting Tuesday evening. He outlined the procedures for hazardous materials disposal, though Ford noted the procedures were not required in TuesdayÕs incident.
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