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Author: Subject: Bad days in the lab or with glassware?
oceandeep67
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[*] posted on 12-1-2022 at 03:27


Quote: Originally posted by itsallgoodjames  
Quote: Originally posted by Fyndium  
I've truly grown to hate magnetic stirrers.

It seems to be a technology that no one has gotten to work reliably. Their speed control is unreliable, the magnetic coupling is pretty much always too weak and causes decoupling every other time, and it is practical only for minuscule amounts of low viscosity liquids, as the electric motor itself is usually underpowered as well.

I have a stirrer that just simply died during overnight stirring.

My stirplate speed adjustment goes on runaway sometimes and it has caused similar troubles. The heating function isn't neither the best there is, but has been able to complete things so far with constant monitoring.

Overhead stirrer, first the improvised one from hand mixer, and then the actual one have been proven to be the best solution so far, and only limitation seems to be vacuum operation, although there are bearings for that too if necessary. The real overhead has power of 100W with brushless DC so it has a lot of torque, likely not to stall with anything that doesn't break the glassware itself and it's silent. The hand mixer, although being otherwise good, is very noisy and obviously overpowered. Having 500W of power, it is actually dangerous as it can even snap fingers if misused. I turned a coupling for it for ptfe paddle stirrers, and although rudimentary, it does it's job very well.

I suppose the brand plates are good, but their price tags start from $1k so it's somewhat prohibitive. Are there any proven good stirrers/stirplates with reasonable price range?


Get a used brand name hotplate from eBay for a few hundred dollars

Build your own.? Custom to fit your needs. If I can do it, I'm sure most of you can...
[Edited on 10-3-2021 by itsallgoodjames]
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oceandeep67
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[*] posted on 12-1-2022 at 03:31


My apologies^
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oceandeep67
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[*] posted on 12-1-2022 at 03:49


Keep in mind I was a child at the time. Like 12 yo. I was performing a combustion reaction in my attic (did not want mother knowing). Anyhow, make a long story short I burnt the house down.:(
So yeah, locals think I'm a fanatic about safety/insane but I/we know how dangerous science can be!
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BAV Chem
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[*] posted on 26-3-2022 at 01:56
A particularly bad week (or two)


So over the past two weeks I've somehow been very clumsy. :(
For one I made some nitrotetrazole over a week ago and it was all looking good until I managed to knock over the beaker, spilling all of the precious solution onto the bench. Most of it could be recovered by carefully pipetting it back up (ik this is terrible lab practice) but then the next day the same thing happened again. At least I managed to recover half of my product somehow...

Yesterday I reached into the cupboard to get out some acetone and knocked down two bottles of formamide and ethyl formate respectively which both shattered on the floor. After cleaning that mess up (nothing was recovered) I found that acetone didn't work for what I was trying to do and that ethyl formate would have been much better. :mad:




Nothing much, just a few useful sites:

Find related papers: https://connectedpapers.com
Get those juicy papers: https://sci.hubg.org
Solubility data: https://chemister.ru/Database/search-en.php
Azeotrope data: http://azeotrope.info
ChemPlayer videos: https://archive.org/download/ChemPlayer
Organic Syntheses: http://orgsyn.org
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B(a)P
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[*] posted on 30-6-2022 at 16:56


So today I was making some ammonium hydroxide using sodium hydroxide and urea. A few minutes in the foam in the gas generation flask started to build. I switched off the heat and instead of picking up the gas generation flask and receiving flask and carrying it to the sink, I removed the top from the gas generation flask and the contents immediately flowed over covering my hotplate. Unfortunately this was too much for my hotplate. After I cleaned everything up i tried the hotplate again. It let out a little smoke and a few sparks and then lights out. I will take it apart in the coming days to see if can be healed.
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arkoma
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[*] posted on 30-6-2022 at 18:58


^^^OUCH. My Corning has survived some pretty heinous spills on it, including hot HNO3. Will be a bad day when it quits.



"We believe the knowledge and cultural heritage of mankind should be accessible to all people around the world, regardless of their wealth, social status, nationality, citizenship, etc" z-lib

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B(a)P
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[*] posted on 30-6-2022 at 20:56


My current hotplate was cheap and is of poor quality. I have had my eye out for years for a good quality one. It seems one of the differences between a good quality and bad quality hotplate is resistance to spills. This one cost me $50 about 5 years ago and may still be repairable. Still, I think I might just bite the bullet and lash out on a new good quality hotplate stirer. Sadly their is no used market for them in Australia, at least not that I am aware of.
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[*] posted on 15-8-2022 at 11:48


Broke my *&^%%&^%*&%* Claisen adapter. Almost impossible to live without one. *sigh*. Wasn't even doing chemistry, just straightening up and I bumped it off the edge of my desk. I've got wood floors, so stuff doesn't ALWAYS break, but not that lucky this time.



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B(a)P
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[*] posted on 15-8-2022 at 15:29


Quote: Originally posted by arkoma  
Broke my *&^%%&^%*&%* Claisen adapter. Almost impossible to live without one. *sigh*. Wasn't even doing chemistry, just straightening up and I bumped it off the edge of my desk. I've got wood floors, so stuff doesn't ALWAYS break, but not that lucky this time.


Sorry to hear that Arkoma, there is a place just up the road from me that sells used lab gear and they have a heap of glass. If it is an obscure and hard to obtain shape let me know dimensions, orientation and joint size and I can take a look next time I am in there. If it is fairly standard no doubt it would be faster to sort out locally.
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[*] posted on 9-12-2022 at 15:24


I made some benzaldehyde: just a small amount, about 5g.
After extracting with a solvent I decided to vacuum distil.
I plugged in my brand new, never-used two stage vacuum pump. My entire product evaporated away in seconds never to be seen again. Now my pump smells like cherries.



Same day. The joint-seize I hate most. I broke another sep funnel. Glass stopper was stuck and I attempted to loosen with a heat gun. Anyone else familiar with that high-pitched "tink" sound that lets you know your glassware is destined for the bin. I should just have sprayed with WD40 and left it for a week.
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wg48temp9
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[*] posted on 9-12-2022 at 15:49


Quote: Originally posted by j_sum1  
I made some benzaldehyde: just a small amount, about 5g.
After extracting with a solvent I decided to vacuum distil.
I plugged in my brand new, never-used two stage vacuum pump. My entire product evaporated away in seconds never to be seen again. Now my pump smells like cherries.


If you have not done so already, as soon as possible drain the pumps oil then flush with clean oil , drain that and fill with fresh oil. There is a good chance your benzaldehyde will gum the pump up.




I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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[*] posted on 9-12-2022 at 20:13


Quote: Originally posted by wg48temp9  

If you have not done so already, as soon as possible drain the pumps oil then flush with clean oil , drain that and fill with fresh oil. There is a good chance your benzaldehyde will gum the pump up.

I am not terribly worried. Running the pump for a couple of minutes seems to have eliminated the smell. And if the worst does happen, fixing it will be identical to the preventative you have prescribed.
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