Archive for the ‘Accidents’ Category

Gas Cylinders on Fire

Monday, July 15th, 2013

Everyone has heard stories of ruptured gas cylinders rocketing across the floor (and through walls), but seldom does one get to witness such an accident. Recently, a truck transporting a load of cylinders crashed on a Russian freeway and created this scene:

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There were several other videos taken from a variety of angles (1 2 3). It’s interesting to watch one cylinder explode after another and to see the kind of speed a ruptured container can build. Obviously, these ubiquitous and relatively inconspicuous pieces of lab equipment present serious risks.

Teacher Sets Fire to Himself

Saturday, June 22nd, 2013

Courtesy of LiveLeak, here’s another great chemistry demo. And by great, I mean stupid…

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 I’m really not sure what the point of the demo was.

About.com Just About Makes Me Vomit

Friday, June 21st, 2013

Whenever you search for any standard do-it-at-home chemistry demo, most of the time you will come across an entry on About.com. About.com is a site that tries to gobble up pageviews so it can attract advertisers, and one method they use for doing this is to pay “guides” to write about popular topics within a particular subject area.

The guide for chemistry is Anne Marie Helmenstine, who earned a Ph.D. in biomedical sciences from the University of Tennessee. Probably sensing an opportunity to gobble up pageviews, Dr. Helmenstine jumped on the liquid nitrogen pool party story. If all she wanted to do was attract hits, that was an excellent plan. Yesterday alone, ChemBark got 21k pageviews, which is about 7-10 times what the site gets on a typical day with a fresh post. But, if your job is to educate and inform, I would not recommend writing this:

Nitrogen is principal gas in air, so it it’s quite safe on its own, but the liquid nitrogen was believed to have reacted with treatments in the pool, releasing toxic gas. How do you avoid hospitalizing your party, if you want liquid nitrogen fog? Simply add the nitrogen to ordinary water, not chemical-treated water. You’ll get fog without additional compounds. The principal risk from liquid nitrogen fog is from asphyxiation. Adding more nitrogen to the air decreases the relative amount of oxygen. This isn’t an issue so much in an outdoor pool, but should be a consideration if you have an enclosed pool. It’s safer to use a fog machine or make real water-based fog in that situation.

That is Dr. Helmenstine’s expert advice, and it is atrocious. First, there is very little chance the nitrogen reacted with the hypochlorite in the pool. Second, adding the liquid nitrogen to non-chlorinated water would have posed the same danger to life as adding it to chlorinated water. Finally, to write that this “isn’t an issue so much in an outdoor pool” is not only wrong, it is a public health hazard. The pool party disaster took place at an outdoor pool.

Ugh!

Awful Idea: Liquid Nitrogen at a Pool Party

Tuesday, June 18th, 2013

There is video circulating tonight of a summer party in Mexico where organizers poured liquid nitrogen into the swimming pool. They weren’t messing around, either—you can see a number of ~10 L dewars being upended into the water.

 

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Of course, this is a very, very bad idea. Under these conditions, the nitrogen (b.p. = −196 °C) quickly boils and displaces all of the oxygen present, causing people in the area to asphyxiate. Remember, it only takes 28 g of liquid nitrogen to displace 22.4 L of air at standard temperature and pressure. The fact that you are asphyxiating is masked by your ability to exhale carbon dioxide normally, so the burning sensation you experience when holding your breath or drowning is absent. Furthermore, the thick fog produced upon mixing the liquid nitrogen and water conceals any distress.

It looks like multiple people were hurt at the party and needed to be rescued.

News reports, updated 21 June 2013: Daily Mail (corrected most of the wrong chemistry, but a caption referencing a reaction with chlorine remains), Latin Rapper Blog (corrected to get the chemistry right; gives ChemBark a shout out, see comments), International Science Times (gets it right, credits ChemBark), Excelsior (gets the chemistry wrong), Fox News (gets the chemistry wrong), MSN Now (gets the chemistry wrong), Huffington Post UK (gets chemistry mostly right, credits ChemBark, but still needs to correct photo captions), NY Daily News (gets the chemistry wrong), The Sun (gets the chemistry wrong), The Telegraph (gets the chemistry wrong in the headline), Popular Science (gets the chemistry right, includes interview and link to ChemBark), Slate (corrected the story to get the chemistry right).

Deborah Blum covered the misreports by the media of the chemistry at play on the Knight Science Journalism (KSJ) site. The post links to ChemBark.

Updated note to media: Many outlets have reported that liquid nitrogen will react with chemicals in swimming pools to generate a poisonous gas. This is almost certainly incorrect. Molecular nitrogen is relatively inert and should not react with anything present in the pool, like “chlorine” (mostly, NaOCl) or water. The danger of adding liquid nitrogen to the pool stems simply from the nitrogen’s boiling and pushing away all of the oxygen around, leaving none for the swimmers to breathe. The cloud that is present has nothing to do with poison gas. Rather, it is the same thing as fog. The liquid nitrogen is cold and cools the air close to the pool to the point that water vapor in the air condenses into very tiny droplets that stay suspended. The cloud is fog, generated from the same effect responsible for your being able to “see your breath” when you exhale on a cold day. The visible cloud is not nitrogen and it is not smoke; it is droplets of water suspended in an atmosphere of air that is heavily enriched in nitrogen.

Major Methane Demo Fail

Sunday, May 19th, 2013

This is how chemistry demos are going to get banned in high schools:

UCLA Chemistry Professor Patrick Harran to Stand Trial

Sunday, April 28th, 2013

Chemical Ed with GogglesThe big news on Friday was that a California judge denied UCLA chemistry professor Patrick Harran’s motion to dismiss or reduce the charges against him relating to the death of Sheri Sangji in a tragic tert-butyllithium accident in Harran’s lab. C&EN and the LA Times both had reporters in the courtroom. Chemjobber and Jyllian Kemsley are curating lists of links.

I’ve weighed in on the subject before, and my views have not changed. There is plenty of blame to go around. Should Sangji have taken more precautions in running her experiment, the most important of which would have been wearing a lab coat? Certainly. She had to have known better, but she paid the ultimate price. Now, it’s past time to decide what responsibility Harran bears in the accident. I think the judge made the right decision in allowing the case to go to trial, and unless the sides strike a plea bargain, a jury will now decide if Harran broke the law. I don’t like Professor Harran’s chances in front of a jury. While most people who’ve been in grad school may recognize the lax oversight by Harran as “normal”, that doesn’t make it legal.

And while Harran faces the possibility of 4.5 years in prison, I still don’t think a prison sentence is warranted should Harran be convicted. The most effective and relevant punishment would be something that specifically limits Harran’s ability to run a laboratory. What I also find distressing is UCLA’s “unwavering” support of Harran. (Side note: Does that include Harran’s claim that UCLA never trained him properly?) UCLA is sending a bad message here; schools should make a point of requiring that professors take their responsibilities in managing labs and training students more seriously.