Sciencemadness Discussion Board

When prudent practice works

j_sum1 - 13-2-2020 at 02:50

I had an experience in the lab today that made me quite pleased with the some of the precautionary procedures I had taken.

I was demonstrating the properties of bromine to some students in an online Chemistry lesson. Well, that was the intent. But when I opened the jar that contained all of my bromine ampoules I discovered all of them wet and clammy with condensed bromine. No gloves.

It was great to be able to calmly reach around the corner and grab my spray bottle of thiosulfate solution and liberally apply it to exposed skin and any other affected surfaces.
It was also great to see that the bed of thiosulfate at the bottom of the jar had absorbed most of the escaped vapours and saved the lid from corroding badly and probably protected everything else in the vicinity.

It turns out that there was a miniscule crack in one of the ampoules where it had been sealed. Not sure if it was a stress crack from when I sealed it or whether it had been knocked. Those Houdini halogens can get out of anything it seems.
Anyway no harm done. But large containers, no secondary containment, no spill neutraliser and no remedial spray and things could have been a lot more messy.

woelen - 13-2-2020 at 03:02

Oh yes, bromine escapes from any container, which is not completely sealed glass. Even a minor crack will lead to problems.
This actually is true for every volatile chemical, but with stuff like Br2 you notice it.
I had a similar experience with my ampoules of SOCl2. After ampouling all of my SOCl2 I put the ampoules in a small plastic bucket with a screw cap and wrapped each ampoule individually in a thick layer of paper tissue. After a week or so, I inspected the new ampoules and on opening the bucket, I was greeted with white fumes of HCl and a strong smell of SO2. The inside was wet and all paper tissue had become soft and immediately teared apart when a little force was applied to it.

I cleaned the ampoules and the inside of the bucket and applied new paper tissue. The offending ampoule was found by carefully smelling at the seals on all ampoules. Just one of them had a smell of SO2, the others were odorless. Only 10% or so of the contents was lost, it is amazing to see that just a ml of SOCl2 can make such a mess. The same is true for Br2.

The secondary packaging and the paper towels assured that no damage was done to surrounding tools and containers.

[Edited on 13-2-20 by woelen]

XeonTheMGPony - 8-3-2020 at 07:51

An ounce of prevention! is well worth its weight in gold.


These are on a bed of sodium bicarbonate in a sealed container.


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Syn the Sizer - 8-3-2020 at 10:30

Quote: Originally posted by XeonTheMGPony  
An ounce of prevention! is well worth its weight in gold.


I agree wholeheartedly, in lab I always label all my beakers with large easy to read labels to prevent accidental mixing of 2 possibly incompatible chemicals. However many of my classmates never label anything. They will grab new beakers and put them in the reagent fume hood with no labels and a clear liquid, have unlabelled beakers in their fume hood or on the bench and walk around the class with beakers full of hot solvents like xylene and no matter how many times the instructor gives them crap they don't learn.

One time a classmate for some reason had a beaker with 98% H2SO4 on the bench (unlabelled) he mistook it for his waste beaker and poured water into it, needless to say it didn't end well, though lucky he didn't get hurt. He failed last semester and is no longer in the class. But still after his mistake my classmates haven't learned.

I am also a strong believer that gloves should always be worn in the lab even if you are not dealing with toxic or hazardous chemicals, you never know who spilled something and didn't clean it properly. Though our instructors aside from the O-Chem instructor will not let us put gloves on if we are not dealing with dangerous stuff, they say its a waste of money, I feel a 10c pair of gloves could save a trip to the hospital.

arkoma - 8-3-2020 at 11:56

J_sum, I believe i can state that you do know how to properly ampoule something. Thought I lost my passport other day---similar level of panic if you can imagine. Calmed down took a nap and found it when I woke up.

j_sum1 - 8-3-2020 at 13:46

Nice non-sequitur there, arkoma. Good thing I know what you are talking about.
Ampouling bromine is quite a different business from ampouling a solid, say, like iron oxide.