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Chemistry lab mishaps

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Sulaiman

Sat Apr 03 2010, 07:11AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

During sixth-form (16-18) I used to run the school chemistry club,
one lunchtime I gave the younger ones freedom to try their own experiments.
Going around checking on what each person was doing one young lad had several test tubes of various chemicals/solutions;
WHAT ARE YOU DOING?
just mixing various chemical to see what happens
GOOD, THAT'S A GOOD WAY TO LEARN
yes, some change colour and some cause bubbles
SO WHAT DID YOU MIX IN THIS ONE THAT'S BUBBLING
this and this, showing Hydrochloric acid and potassium ferricyanide solution
OK, EVERYONE OUT, NOW!

On another occasion I was demonstrating acetylene (ethyne) bubbled through silver nitrate solution in a fume cupboard.
Suddenly there was an almighty bang!
much too loud for the ammounts involved, and not even filtered and dried yet.
Unknown to me a technician was reparing the fan motor on the roof, he made a slip and the motor fell down the flue pipe from the roof into the fume cupboard.
I almost had to change my trousers

Trying our hands a organic chemistry we made a compound (forgot the name - anyone know what it's called?) that has an odour described as rotting flesh, so small quantities...
schoolkids don't quite comprehend 'small quantities'.
Anyway, after four or five hours the science block could be used again..

For a while (15/16 years old) I used to carry quantities of 'interresting' chemicals around with me.
My biology teacher confiscated all of them just because I was sprinkling magnesium powder into a bunsen burner flame.
Some days later I was summoned to the office of my head of house,
He said "I've had these chemicals checked by the chemistry department and they said there's enough explosives here to blow up half the school"
I replied " no sir, maybe half one building block but not half the school"
He gave me the chemicals back and advised me not to bring them to school again.
I don't think that modern schooling is quite so liberal.

I shall not discuss most of the chemistry mishaps that I and my friend had out of school for fear of possible emulation - suffice to say that we made just about every explosive that we read about. With various close-calls.
One of our favourite fun/safe explosives was nitrgen triiodide - touch sensitive.
My friend had a filter paper with some almost-dry, flicking little bits out of the window watching/listening to it hit the concrete below.
Whilst doing this the NI3 dried out and all went off at once - exploding in my friend's face.
Luckily he wore spectacles so his eyes were safe - but for several days he had a lovely iodine-coloured face with white where his spectacles were, sort of a complimentary Mask of Zorro.

aonomus

Sun Apr 04 2010, 03:36AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

In my advanced organic synthesis course at my university (or even in other labs), I haven't seen too many accidents. What accidents, near accidents, or hazards that come to mind:

1. Release of ethyl mercaptan in a fume hood on a 5th floor research lab. Half the campus was evacuated because everyone suspected a gas leak. The entire chemistry wing was completely unaware due to our continually fresh air, and already mostly dead sense of smell - lesson learned: fume hoods vent directly into the atmosphere for research purposes.

2. Vacuum line antics
Vacuum lines for air-free synthesis end up going to a high-strength vacuum pump which must be protected with a cold trap, cooled by liquid nitrogen. The problem is that if too much air is drawn into the vacuum line, oxygen condenses in the cold trap, making it a explosion hazard. If solvent from a reaction then gets vacuumed out and into the cold trap, it has a good chance of simply exploding in the cold trap, sending glass shrapnel everywhere.

I've seen this happen once at the end of someones reaction where they lowered the cold trap and saw the deep blue hue *AFTER* they had used the vacuum to draw off some very high-boiling solvent. I alerted the teaching assistant and lab tech, and called it a day.... nothing happened, but everyone was scared after made aware of the potential hazard.

3. Air free technique and syringe antics
I have a personal issue with needles in general, but handling pyrophoric substances such as n-BuLi or worse aren't too uncommon in the organic chemistry lab. Essentially what you do is using a flow of inert gas, prevent air from contacting your reagent between the bottle, and the reaction vessel by various means. I never started any fires, but I was nervous as hell, I did see someone else though clog a syringe after they had finished using nBuLi with it, and attempting to clean it by using a syringe to pressurize the needle with water, giving themselves a nice shower as the needle popped off the luer lock fitting.

4. Quench day
Eventually at the end of term, any leftover reactive chemicals that have 'gone off', gone bad, partially hydrolyzed, are contaminated, etc are 'quenched' and made chemically inert. Quenching is typically done by slowly introducing some sort of a proton source such as methanol into a container containing the chemical that is to be quenched. Heat is released and a vigorous reaction occurs, sometimes with the release of a gas and formation of salts.

I have learned that with these salts forming, they can form quite hard 'cakes' that trap nice pockets of concentrated reagent *well after* the entire bottle has been filled with methanol, then water, and nothing seems to be happening. Eventually the water makes its way to one of these pockets of reagent and you get a small geyser of water going up.

Things like sodium metal form hydroxides on their surface when in organic solvents, adding methanol doesn't quite do the trick because the hydroxides aren't soluble in methanol too well, eventually they flake off and increase the reaction rate considerably.

5. Thionyl chloride and ethylene diamine
This was a fun day, I had to dispose of a container of thionyl chloride into a waste bottle, and not knowing that another assistant lab tech had just thrown out a non-trivial amount of ethylene diamine into the previously empty bottle. As soon as I pour in a few drops, the entire bottle goes up in smoke, filling the fume hood with a dense white/brown smoke. I jumped back (amazingly not spilling any thionyl chloride on myself in the process), set the bottle down, closed the hood, stripped off my gloves, and waited for the smoke to clear...

6. Glass temperatures
Ok, so its obvious, there is no visible difference between hot and cold glass. The not-so-obvious part is the difference between your flask that had been cooled, and another students round bottom flask that was just taken off heating and still burning hot. Self explanatory.

So all in all, no major accidents, a few close calls, and the occasional bump or scrape. Chemistry isn't a hazard-free field, but its not a deathtrap either.

Martin King

Wed Jul 28 2010, 01:09AM

Registered Member #3040 Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237

Sulaiman wrote ...

Unknown to me a technician was reparing the fan motor on the roof, he made a slip and the motor fell down the flue pipe from the roof into the fume cupboard.

So you were using a possibly inoperable fume cupboard and he was repairing a fan without making sure the fume cupboard wasn't in use and not posting a notice on it !!!! That's not a mishap, that's incompetence on the technicians part! I've never used a fume cupboard but I've worked in places that have them and I would have though that there would be an airflow sensor to warn if the fan was defective, after all most modern domestic boilers have such a sensor and it's not rocket science.

Martin.

Adam Munich

Fri Aug 06 2010, 04:03AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Poisoned by released HCN from a leaky apparatus. That's my worst tale. Reduced my lung capacity to 75%.

quicksilver

Fri Aug 06 2010, 04:10PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Grenadier wrote ...

Poisoned by released HCN from a leaky apparatus. That's my worst tale. Reduced my lung capacity to 75%.

That's really terrible; I'm seriously quite sad that happened to you. Did the doctors say you may ever regain the lung capacity in the future? Was there ANY way the whole thing could have been avoided? That's honestly a F**king shame.

Adam Munich

Fri Aug 06 2010, 04:32PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

It's up to about 80% now, but I don't see it getting any better. It could have been avoided by not breaking the boiling flask.

I haven't repeated the experiment since, and never will.

IntraWinding

Sat Aug 07 2010, 04:47PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

I made the totally stupid mistake aged 13 or so of sniffing an inverted funnel to see why it wasn't bubbling Chlorine. It was a shocking and horrible chocking experience with effects on my breathing for some hours. At first I had to force myself to breath deeply and wheezily for about half an hour while I recovered from the worst of the effects. It gave me a terrible headache for some hours and basically the rest of the day was written off. Even a few days later I could taste a little blood when I coughed. My mum had phoned the doctor, but he didn't think I needed to go to hospital, and I guess he was right.
Why was I playing with Chlorine? I was really bored and trying to make a little of the explosive oil Nitrogen Trichloride. And I guess I got off lightly with Chlorine poisoning, as in 1811 it cost Pierre Dulong an eye and three fingers!

That Lateral Science site is great by the way!

Don't miss the hilarious ERNEST GLITCH CHRONICLES

Adam Munich

Sat Aug 07 2010, 05:05PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Definitely chlorine. When it comes in contact with the water in your lungs it forms hydrochloric acid, and thus burns like hell.

Mike

Sat Aug 07 2010, 11:55PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

I've got a pretty dumb (okay magnificently dumb).
I needed to heat up some acetone, and instead of doing it the correct way with a hot water bath or heating pad, i went full out with torch flame on the glass. I think we all know how that one ended up. KABOOM shattered glass and now a 10oz of acetone on fire everywhere. Luckily I had one brain cell in use in that I did this stupidity over concrete so the fire burned out without harm but it could have been much worse.

Martin King

Sun Aug 08 2010, 09:06PM

Registered Member #3040 Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237

Before I had a better awareness of chemistry (very early teens) I remember mixing various cleaning products that where in the bathroom while having a bath, luckily I recognised the smell of chlorine (my dad built and looked after the school swimming pool) and knew that it was bad so jumped out of the bath and chucked the whole lot into the bath water and emptied it. From that day my "experiments" were far more cautious.

Martin.

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