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    Why Scary Lab Accidents Happen
    By Enrico Uva | September 10th 2012 02:00 AM | 18 comments | Print | E-mail | Track Comments
    About Enrico

    I majored in chemistry, worked briefly in the food industry and at Fisheries and Oceans. I then obtained a degree in education. Since then I have...

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    If a chemist has never been in a lab accident, he has been lucky. Of course luck is more likely to come to those whose mentors have learned from bad experiences and to those who have taken preventive measures seriously, despite their anal nature. Chemical reactions create products with behaviors that differ from those of the ingredients. That's what makes them intriguing, and it's also what makes them potentially dangerous. No matter how simple and controllable a reaction seems on paper, when it's carried out in real life, the exact conditions determine its rate. And when gases or acids acquire too much kinetic energy, no one wants eyes, lungs and flesh in their way.

    As an adolescent I played with my chemicals more than my instructors did. Rarely did they carry out demonstrations while lecturing. Seldom did they deviate from the tight parameters of cookbook labs. So I unconsciously associated accidents with amateurs or with large scale industrial processes. But after a freshman year of chemistry, I got my first summer job in the lab after a metallurgical company did not rehire a chemistry student previously involved in a serious analytical lab accident.

    One of the most ineffective ways of teaching something is to present it as a rule without explaining why: "Add concentrated acid to water; never water to acid." But using a small quantity to show how things can go wrong will get the message across.  Just do it on the side of a two-way fume hood while making sure that the glass is lowered on the side of observing students.  As the less dense water remains on top, the exothermic reaction on the surface brings the top of the mixture to a boil, and of course acidic solution splashes all over the place. The acid is quite strong because the reaction occurs so quickly that little dilution occurs.

    A university student working as a replacement for vacationing technicians had been pressured into quickly preparing a standard solution. To save time, so he thought, he measured concentrated sulfuric acid and poured it into a glass jug. He added water to it, screwed the cap on and shook it vigorously from side to side, across his chest. The heat, steam and closed container combined to increase the pressure enough to rupture the glass, and most of the acid ended up on his body. He was in such pain that coworkers had a hard time dragging him to the emergency shower. He ended up with scarring, third degree burns. What happened was consistent with a keen observation by one of the authors (Jacques Vilain) of a book about reducing chemical mishaps:
    Each accident is a unique, often bizarre, event, albeit with repetitive patterns but great 'variability' in terms of cause/consequences ratio.
    About 15 years ago, I wanted to show my students how soft a metal sodium is, and of course I planned to subsequently demonstrate its classic, fiery reaction with water. Luckily I was wise enough to use the two-way fume hood setup. I cut the block, exposing its lustrous interior--the surface slowly oxidizes with time even when it's kept under oil. But I had made the mistake of not taking tongs with me. I had actually used my pocket knife to pull it out of its bottle, and after cutting it, I poked my knife into one of the halves and placed the knife and sodium into a beaker of water.

    Any time an exothermic reaction is carried out, the vessel should be checked for cracks. I only noticed the dark line in the glass after I dropped in the knife and sodium. At the time I was also unaware of the precautionary trick of placing sand at the bottom of a beaker. It helps prevent overheated pyrex from cracking. My last error was my worst one: sticking a knife into too large a piece of sodium is a bad idea because it causes the chunk to sink into water. Without the added weight, sodium, with a density of 0.97 g/cm3, would not have sunk and not all of its surface would have come into contact with water; the reaction would have been slower and more controlled. The hydrogen would have ignited, but the reaction would not have generated as much pressure as when sodium is submerged.

    To complete the disaster, our technician had recently left methanol in an open beaker in the fume hood. There was an immense explosion heard across our small school. The observing students gaped in astonishment but were unharmed since the protective pane on their side could not be opened. The fume hood glass on my side did not break, but all the glassware within it did.  I had never totally lowered my window, and sodium hydroxide (NaOH) produced by the reaction along with bits of glass projected towards my belly. A couple of pieces actually got stuck in my shirt. When I unbuttoned it, I saw no blood but found NaOH reacting with my belly.

    Although I washed it off, by the time I got home that evening I had developed a second rash. Coincidentally, during that week I had experienced an allergic reaction. (It proved to be the new detergent my wife had bought) The next evening I told the dermatologist to ignore the NaOH rash and try to figure what was up with the rest of the redness. He looked at me as if I was from a different planet. But the reason I was in one piece and that my students were home safe was that in spite of all the errors committed, I had had the good sense of conducting a risky experiment in the safer environment of a fume hood.

    About 10 to 50 times more lab accidents occur in schools and universities than in industry.
    If there's more than one way to do an experiment, and one of those ways will result in disaster, then somebody will come along and try it that way.
    This variant of Murphy's Law materializes more frequently in academia due to inexperience on students' part and the fact that both Ph.D candidates and faculty often work alone in the lab. The long hours they put in create overfamiliarity with the surroundings and lead to a false sense of security. But in industry, lab workers are very rarely allowed to solo it.  Dupont Chemicals and other companies send even minor accident reports directly to the chairman of the board. In the looser atmosphere of academia there is a greater chance that a lab accident will go unreported. Many lab accidents from all sources, however, do show up in blogs and other online sites.
    At the other extreme, regulations can get overdone and safety officers can over-police. The resulting atmosphere can get stifling and hinder creativity. I remember walking into a pharmaceutical research lab a few years ago. They were shutting it down and donating most of their equipment. Nothing was plugged in. All the chemicals had already been removed, but I still wasn't allowed to walk in without a lab coat and safety glasses. You can imagine what that safety officer was like when the lab was up and running!

    What probably works best is a physical environment designed to minimize accidents. I recently visited McGill University's new main graduate chemistry lab and was impressed. Every experiment was taking place under a long lineup of fume hoods. A spacious walkway separated it from their work stations, which were all behind Plexiglas and facing the fume hoods, allowing them to keep a watchful eye on their experiments while they wrote or researched. Separated from the labs, the chemical stockroom was easily accessible and actually maintained by someone with a sense of order. It was as clean as a pharmacy! The common work and lab areas minimize the probability that somebody will work alone.

    Sources:

    Credits---Cartoon source---I hope chemist and cartoonist Nick Kim considers this an educational, non-profit use of his work. At a rate of $0.0005/reader... :)

    Comments

    vongehr
    Great article - I in fact have never seen the explanation for why one should not pour water into H2SO4 anywhere written, though I have seen it many times as a rule. I figured it myself, but that needs understanding of physics (density etc.), so many chem/bio/etc. students just learn the rule, and if they remember it the wrong way ... zing!
    He added water to it, screwed the cap on and shook it vigorously from side to side, across his chest.
    Well, now that is idiotic no matter what. What the hell was he thinking?
    I poked my knife into one of the halves and placed the knife and sodium into a beaker of water.
    Oh - I see - he was thinking the same as you - not at all. ;-)
    The hydrogen would have ignited, but the reaction would not have generated as much pressure as when sodium is submerged.
    That is dangerous. The hydrogen often does not ignite for too long and a large volume of H2 in air accumulates. If it finally ignites, BOOM. In fact, it is better to submerge it (under a fine sieve, not hoping it stays stuck to a knife although it dissolves), because then the H2 is not mixed with O2 where the hot Na is, so it just bubbles out. That is how I got rid of up to 5 or so gram Na at a time from my beam doping cell at USC. Exploded only once after doing it perhaps 20 times - I still cannot imagine why.
    UvaE
    What's also dangerous is adding sodium to ice. The inexperienced might reason that the lower temperature will slow down the reaction. But some pieces of metal melt their way into the ice and become encapsulated--just like an ice cube can stick to a knife because the melting actually removes energy from the metal. So what happens after is that the hydrogen formed is under a great deal of pressure. The "fireworks" then actually spread some unreacted  sodium.
    Let me demonstrate:(Students were 30 feet away and with goggles--I was probably too close, but I was wearing a face shield)
    rholley
    At school, our Chemistry Technician once threw some sodium out on to the snow (which we used to see quite often in those days.)

    It created a very loud detonation which was startled people right at the other side of the school.  However, we who were much closer at the time, in the Chemistry lab, did not hear it at all.

    This is still a mystery to me.
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    UvaE
    Was it thrown on the other side of a snow bank, so that the snow would have insulated the sound traveling in your direction? 
    vongehr
    Ice - bad idea for sure! Why people have such bad ideas, ha ha. The absolute worst is to have the metal molten, like if you put Na and K together (the alloy is fluid at RT). The surface of a metal piece is small, but if it is a fluid, the whole almost instantly reacts once the fluid splashes a little due to the initial reaction. If a drop falls down, it won't reach the floor. Did I ever tell you about the guy who bought Rb and wanted to get it out of the glass vial? It was just a little Rb, perhaps ~3 cm cubed. One fine day, his fume hood is blown up, and his labcoat black and ripped, and fire extinguisher powder everywhere, and he complains that probably thousands of dollars worth of computer and laser equipment are toast, because if you have alkaline dust inside a circuit board, it will fail pretty soon. He used a hairdryer to melt the Rb in order to pour it out of the vial! And he is quite knowledgeable about both, chemistry and physics.
    UvaE
    Fluid alloy of Na and K at room temp, hmm...I have to get hold of a high speed camera with a good zoom so it could be at a safe distance  :)

    Molten sodium in chlorine is a classic and beautiful reaction too. But since I have first hand experience with choking on chlorine gas--it's like knives in lungs--I only show videos of that one.

    My wife gave me a safer demo, but again you have to keep spectators bespectacled and many meters away and performer has to wear a face shield:
    flatten out very small amount of potassium (the flattened disk, 3 mm in thickness, should be less than the diameter of the hammer), pepper with solid iodine and pound it with a hammer. Any extra potassium stays on site, but if in excess, iodine will spread and permanently stain linoleum floors. It's loud but the product is a harmless salt.

    By the way the face shield is to avoid iodine in eyes. I've experienced that too in college. Extremely painful, I don't know how I didn't damage my cornea. It was from nitrogen triiodide that inadvertently exploded without me touching it----probably too close to a radiator.
    vongehr
    small amount of potassium (less than diameter of hammer)
    Chemists quite usually give entirely useless descriptions of physical quantities - why is that? This could be a ball with almost the diameter of a sledge hammer or a monolayer of K atoms over less than a small hammer's face. No wonder labs blow up.
    UvaE
    The flattened disk, 3 mm in thickness,  should be no bigger than the diameter of the hammer---I made the correction.

    Chemists quite usually give entirely useless descriptions of physical quantities - why is that? 
    That's really not the case.
    vongehr
    Actually, it is the case. "Copious" amounts, washing "several times", giving one ingredient in terms of concentration, the other in ml (so one does still not know the necessary ration between them), ... . It happens so often, I wonder whether it is deliberate so that other people have difficulties reproducing the reactions (slow down the competition).
    UvaE
    giving one ingredient in terms of concentration, the other in ml (so one does still not know the necessary ration between them) 
    But n = CV, so if you can calculate moles, and the equation will reveal the ratios, then you can obtain mass, ...unless you mean that the equation is not revealed.

    It happens so often, I wonder whether it is deliberate so that other people have difficulties reproducing the reactions (slow down the competition). 
    You're right that it happens in journal papers that are definitely not meant to be recipes--though i wonder if the authors are more cooperative when a third party has to reproduce the results . But as far as chemical analytical procedures go, which are crucial in the day to day operation of industrial labs and water treatment centers, those are very clear.
    rholley
    At last — I can go one better than Sascha, namely with Caesium!

    Our group had been doing some reactions with Cs under xylene, and the residue had been lying around for some time.  Our technician, asked to dispose of it, had put it down the sink, and it detonated in the trap underneath.

    Fortunately, it was only a tiny amount, and the trap was not shattered.








    “Of course, you have to keep him supplied with wine.  Give him water and he’ll explode!”
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    UvaE
    Fortunately, it was only a tiny amount, and the trap was not shattered. 
    That was a potential disaster in the making because, as you probably know, methane from decomposition has been known to form in  traps!

    Bonny Bonobo alias Brat
    Scary lab accidents were the high spot of my school days, apart from learning to play Lacrosse (which is probably the best and roughest team game in the world) and I remember most of them in great detail, especially the out of control nitrous oxide laughing gas experiment that involved the whole school.
    On most occasions the scary lab accidents usually just involved an explosion followed by our chemistry teacher's clothes or flesh dissolving in greater or lesser amounts in front of our eyes, while we desperately tried to neutralise whatever was on her clothes or skin with the appropriate antidote while she gave instructions. I can remember her tights dissolving into bloody holes on several occasions but she always remained pretty calm as she told us what to do to help her.

    Amazing though it seems now looking back, we didn't even have any 'fume hoods' or gas chambers, as we were the first hand-picked half a dozen girls to ever do chemistry and physics at this 200 year old school for 'young ladies' as an experiment against tradition. To her credit I should mention that none of us students were ever injured, even though we were encouraged to go to the chemistry lab in our lunch break and play with the safe chemicals! We often dropped sodium metal into water in the sink just to watch its spectacularly journey as it reacted with the water, that was fun :) 
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    UvaE
    we were encouraged to go to the chemistry lab in our lunch break and play with the safe chemicals! We often dropped sodium metal into water in the sink just to watch its spectacularly journey as it reacted with the water, that was fun :)
    Sodium is not in the safe category of chemicals, but it's great that no one was injured and that you only have good memories.

    My students have told me about a  fair number of junior college chemistry classes that are all lecture and demo-less. That's like teaching hockey without a puck 
    After taking all the precautions it's better to risk that still 1 in 500 chance that something will go wrong than to strip the soul and life out of a subject.
    Bonny Bonobo alias Brat
    Well chemistry without the practicals would definitely have stripped the soul and life out of the subject for me. Our teacher was a wonderful, very good humoured woman, the problem was she was often doing experiments for the first time and following instructions from a book, a bit like a cookery class but with much more interesting but unpredictable and less appetising outcomes. As someone mentioned above, the ratios and measurements were not always very clear, which was probably the main part of the problem and we didn't have fume hoods for when things went wrong, which was a big problem!
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    pknoepfler
    We have our share of accidents in biology labs too, especially in the biomedical sciences. I once (in the early 1990s at UCSD) had colleagues who had a 60L carboy of concentrated NaOH up on a lab bench (they used it to clean an apparatus free of residual radioactive iodine). Its entire contents leaked onto floor overnight. 
    I was the first one in the lab in the morning and by the time I realized the floor was covered by a couple inches of some liquid I was standing in the middle of the room surrounded by a tiny but very dangerous "lake" of concentrated NaOH. I tiptoed it out of there and called EHS....they spent hours in their "space suits" cleaning up the room. The culprits got just a slap on the wrist. I was really mad. I didn't even know they were doing something so stupid.

    I suppose if I have slipped and fallen I might be dead?

    Speaking of liquids there was the time as a grad student I flooded my entire lab with water by accidentally breaking off a cheap plastic sink faucet when washing my hands to head home for the day on the weekend. A jet of water shot up to the ceiling....ever have one of those moments when you feel like you can't believe what is happening.

     Not so dangerous to the lab and amazingly my PI was very understanding. If I had had a different PI, it might have been dangerous to my career as a grad student I guess. My biggest worry were the lab notebooks, but I managed to get them out of the lab dry with just a couple drops on the covers of a few. NO equipment damage. 
    Paul S. Knoepfler, Ph.D. Associate Professor UC Davis School of Medicine http://www.ipscell.com
    UvaE
    I suppose if I have slipped and fallen I might be dead? 
    You probably would have survived, but it would have been scarring. They could have used just diluted sodium hydroxide whose purpose is to convert the molecular form into ionic forms. Unless they did just that but left the original and more concentrated form on the lab bench.

    In my years in science, I have had a few lab accidents. They have happened when I was too tired to think straight and should have been home, or when I was being pressured to rush something through and didn't have the wisdom or wit to push back.

    Discussions of lab accidents and lab safety reminds me of a saying my father (a retired engineer) is fond of using. "Good judgment comes from experience, and experience comes from bad judgment." :-)