18thTimeLucky
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Posts: 51
Registered: 19-8-2017
Location: The one-and-only tea and crumpet land (UK)
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Mood: 0 Kelvin and still won't crystallise from solution
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What happened to my conical flask?
I have never broke any glassware, excluding 100ml glass containers that is. If you do not exclude them I have broke 2 conical flasks and two beakers,
typical as I have plenty of 250ml stuff which I use more but hardly any 100ml as I always break them!!  Anyways, this is one of the conical flasks I have broken but I am not sure how it occurred.
I had been carrying out the synthesis of some tetraamminecopper(II) peroxydisulfate a while ago which required a chilled solution of ammonium
peroxydisulfate. I added some distilled water to a 100ml conical flask and started to add some of the ammonium peroxydisulfate.
I consequently heard what appeared to be glass clinking sounds, if I remember correctly, almost the sound of metal crystallising. I wasn't sure why
this was occurring but I certainly was not very happy about it. My ominous feelings were confirmed as a long crack split part of the glass near the
base of the flask, out of which a very small amount of the solution leaked.
I meant to make a post a while ago asking what the hell happened to the flask to make it crack like that? I highly doubt it was due to any heat
released by the ammonium salt when dissolving. I was, and am still, quite stumped.
(After sorting out the situation I had put the flask to the side and forgot about it, as shown by the dust collected on it and crystals coming out of
the crack in the glass after the water had evaporated)
![IMG_8039[1].JPG - 1.7MB](http://www.sciencemadness.org/talk/files.php?pid=509751&aid=65811)
Yep, I have a chemistry blog!
18thtimelucky.wordpress.com
"Amateur chemistry does seem like being in a relationship with someone very beautiful and seductive but has expensive taste, farts a lot and doesn't
clean up after themselves, but you love them anyway" - a dear friend |
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LearnedAmateur
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Registered: 30-3-2017
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First question: how old was the flask? I’ve broken borosilicate flasks and beakers under gentle heating before where new ones would be able to
handle it well. If it happened to be dropped (even just a ruler’s length) at some point then there may have been imperceptible cracks which
could’ve propagated under stress. A perfect, well made flask should not break under most synthesis conditions, like I’ve dumped sulphuric acid
into water within borosilicate glassware and hit them with an ‘ungauzed’ flame, and they tolerate the fast heating.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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Sulaiman
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Could it be that cold water + endothermic dissolution caused ice to crack the flask ?
EDIT: or as ammonium persulphate is so soluble it could just be a very rapid cooling that stressed the glass.
[Edited on 7-3-2018 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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18thTimeLucky
Hazard to Self
Posts: 51
Registered: 19-8-2017
Location: The one-and-only tea and crumpet land (UK)
Member Is Offline
Mood: 0 Kelvin and still won't crystallise from solution
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Quote: Originally posted by LearnedAmateur  | | First question: how old was the flask? I’ve broken borosilicate flasks and beakers under gentle heating before where new ones would be able to
handle it well. If it happened to be dropped (even just a ruler’s length) at some point then there may have been imperceptible cracks which
could’ve propagated under stress. A perfect, well made flask should not break under most synthesis conditions, like I’ve dumped sulphuric acid
into water within borosilicate glassware and hit them with an ‘ungauzed’ flame, and they tolerate the fast heating. |
Well the flask is relatively new. Along with some other equipment, it was a present I received September last year, bought from Better Equipped I
think. I don't think it had suffured any sort of drop, although I could be mistaken. This had been the first real anything I had done with it as far
as I remember and it failed catastrophically. Maybe then it was just a dud? The rest of the glassware I had also received has withstood many a
reaction and usage.
| Quote: Originally posted by Sulaiman | Could it be that cold water + endothermic dissolution caused ice to crack the flask ?
EDIT: or as ammonium persulphate is so soluble it could just be a very rapid cooling that stressed the glass.
[Edited on 7-3-2018 by Sulaiman] |
Maybe. Still seems a bit extreme for it to break even from that. Perhaps I will just have to be satisified with the answer that I was unlucky and the
flask was weak and just broke with its first usage went put under minor stress.
Yep, I have a chemistry blog!
18thtimelucky.wordpress.com
"Amateur chemistry does seem like being in a relationship with someone very beautiful and seductive but has expensive taste, farts a lot and doesn't
clean up after themselves, but you love them anyway" - a dear friend |
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