Sciencemadness Discussion Board - Bad days in the lab or with glassware?

Bad days in the lab or with glassware?

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j_sum1 - 2-1-2021 at 00:21

I decided I needed some bulk concentrated ammonia for production of ammonium oxalate. I had previously bubbled NH3 into oxalic acid solution but had high losses from solubility. So, this time I decided to begin with ammonia solution and thrn add oxalic acid.

Working on a scale about 4 times larger than I had ever done before, I set up an ammonia generator using Ammonium sulfate and sodium hydroxide in a large filter flask. Unfortunately, it frothed up, blocked the outlet hose, popped the stopper and vented NH3 into the room.

Reaction slowed without proper mixing of the slurry. However, that still left a kilo of unreacted material to clean up. The only idea I had was to immerse the flask in a bucket of water and allow the water to capture all of the ammonia vapour. This worked. However, it felt a bit wasteful. I ran some calculations that suggested I would reclaim much of the ammonia as the oxalate salt if I added oxalic acid to the bucket. I would lose 360g but stood to recover about the same amount.

That started a long day of filtering at bucket scale. And when it was finally done, my product was not behaving as expected. It turns out that I had forgotten to consider the solubility of sodium oxalate: which is similar to ammonium oxalate. I now have several hundred grams of mixed sodium and ammonium oxalate. It will do for my purpose, but I had chosen the ammonium salt deliberately to keep alkali metals out of the situation.

Never mind. I have had a lot worse dsys in the lab than this. Filtering is do unrewarding though.

B(a)P - 11-2-2021 at 13:19

Yesterday I was using my favourite thermometer to stir a mixture that had become to thick for the magnetic stirrer. I know I shouldn't, but it just looks so robust. Turns out it is not so robust.

draculic acid69 - 12-2-2021 at 04:04

Wrapped all the joints with PTFE in a dist. Apparatus to attempt
my first vac distillation and ats soon as I attach the receiver
I hear that terrible "tink" sound. The receiver cracks all the way
from the gg joint right down to the bottom of the flask.
I'm only going to use vac grease from now on.
Dam cheap Chinese joints
too little PTFE and it leaks too much and "tink".
Dammed if U do dammed if U dont.

Fyndium - 12-2-2021 at 11:03

I have used paraffin oil for my joints for a long now. It gets pretty thin in hot joints, but adding a little now and then from a dropper bottle seems to keep it mostly in order.

I started using paraffin oil in my vacuum pump because I couldn't find any vacuum oil and the few I found, were so expensive it was not even a good joke anymore, and as pumps accumulate all the crap that comes over through vacuum outlet, from solvents to water, which emulsifies with the oil and lowers the ultimate vacuum due to increase in vapor pressure, it is good to change the oil pretty frequently, hence the very low price of paraffin oil comes handy. I've changed the pump oil more in the last 4 months than in the last 10 years. I've used it everywhere that needs lubrication, and also add it to distillations to not allow it to run dry. It's cheap and easily available everywhere and has very low vapor pressure and good lubricating properties and does not react with anything, except maybe hot nitric acid and is also odorless (except when heated for long time, but imo the smell is very pleasant, something along candles) and harmless for health. Oh, and I add half a dozen drops in every thermowell to cover the bottom 10mm with oil for the probe.

What this has to do with cracked glass and joints? Nothing, actually, it's on the teflon thread tape side. I wrapped enough layers for 24* thermoprobe to fit into a 29* joint for a flask because with an adapter the probe was way too short, and everything went mostly well - until I stopped the reaction and shut the valve to prevent air entering and oxidizing the hot product. Some time passes, and I go check my stuff, and of course the cooling reaction created a vacuum inside the flask - and right in front of my eyes the probe pops loudly into the flask, crashing through the bottom, and leaking all the contents into the cooling bath. That was 300€ pop for the 3-neck flask. Ironically the probe was fully intact and I still use it on daily basis. Lesson? Never, ever use anything improvised or take shortcuts, unless you want to prepare for extra costs or a huge mess. Funny though, I recovered 100% of the product, which accumulated as a clean layer to the bottom of the bath vessel and it was even washed clean by the cooling bath water, requiring little neutralization afterwards. Sad that I don't do anything for money for the mess-up to be worth it so it's all 100% loss, whatever way it goes.

arkoma - 12-2-2021 at 14:23

Fyndium, by paraffin oil, do you mean what they call mineral oil here in the States?

Fyndium - 12-2-2021 at 15:37

Yep, the liquid stuff that doesn't taste or smell anything and is used on wood, babies and other stuff.

There appears to be two scholars of the stuff:

https://en.wikipedia.org/wiki/Mineral_oil

https://en.wikipedia.org/wiki/Liquid_paraffin_(drug)

arkoma - 12-2-2021 at 20:47

ok. i've using PTFE tape, and as a matter of fact I had a neck crack on my 500ml triple neck about six weeks ago....

Fyndium - 13-2-2021 at 00:54

I've been afraid of the tape because it could concentrate a lot of force on a small area and spreading it evenly and to provide good seal might be tricky. Ready-made PTFE joint sleeves would be ideal, but the cost isn't, as chinese don't sell them for some reason.

Fyndium - 16-2-2021 at 21:51

I thought I figured out a good way to store my ebulliator tube by placing it in a plastic pipe with paper topping to prevent it sliding. Apparently it wasn't tight enough as I was going through my stuff and grabbed the tube by the end, and the ebulliator dropped out, bleeder head first straight to my finger and broke leaving me with two glass needles sticking out. Luckily they didn't break under the skin, but it still felt nasty pulling out almost a cm long glass needles off my finger.

Gotta draw the bleeder head again. As I just made it perfect last time. I've gotten pretty good at it, actually.

Fyndium - 6-3-2021 at 02:30

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?

itsallgoodjames - 10-3-2021 at 08:00

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

[Edited on 10-3-2021 by itsallgoodjames]

arkoma - 10-3-2021 at 12:15

I bought a used Corning PC351 on ebay for $90US, shit, 3-4 years ago? Still works like a charm, and will pull a vortex in my 2 liter erlenmeyer using a large egg stir bar I got from Dr Bob.

pneumatician - 18-3-2021 at 19:35

Quote: Originally posted by the Z man

Other accidents:
-In my rookie days (about a year ago

) I had a splash of hot concentrated NaOH soln on my face and in my right eye while making hydrogen adding aluminium. Runway reaction, you know. Luckly for me I was close to the tap. Nothing more that pain to the eye for one day, but I have been scared a lot.
-Sulfuric and nitric acid eruption from a flask upon addition of AN to conc H2SO4 that turned out to be contamined with EtOH. The acid jet passed about 5 cm from my face (obviously without goggles, also see above) and it was strong enough to hit the ceiling. It was a mess to clean before it could damage the wooden floor of my bedroom.
-Fire from 100 ml acetone I was boiling on open fire

. Half meter fireball :cool:

-The same with ethanol :cool:

Yes, I am stupid.

this is very funny! LOL! and very crazy!!

pneumatician - 18-3-2021 at 19:55

when I are in a upper floor in the chem school drawing technical in a big, long and heavy table of 6m aprox a big BOOMM happend. I noted the explosion in my ass sitting on a chair. The table jumped! A lot of ambulances come... Some guy in a mortar mix, if I don't remenber bad, phosphorus and nitric acid... and the result, 2 corneal transplants.

Is very dangerous work with others persons, stupid egos pop up, alpha idiotic males, or simple assholes with no neurons :-)

itsallgoodjames - 19-3-2021 at 10:50

Quote:

Is very dangerous work with others persons

I'd contend with that and say that for some things, having another person around incase something goes wrong is basically a must. Just as long as that other person acts responsibly

the chemistry stories thread

BauArf56 - 6-6-2021 at 03:04

on SM there a lot of different stories from different users about failed experiments, stupid things done during an experiment, improvised apparatus, experiments done as teenagers and so on. I thought that a thread about these stories would be great, so one doesn't have to search into different threads. For example i once wanted to electroplate things with nickel, and since i didn't have any acid strong enough for dissolving it, i scraped some of the nickel coating from a few magnet and dissolved it in a concentrated solution of copper sulfate. But on contact with various metals, such as magnesium and zinc they were plated with a grey substance. That's an example of a failed experiment. Any story is welcome!

Mailinmypocket - 7-6-2021 at 04:39

As a teenager (15 years old-ish) I made a flash powder with Mg powder/KNO3. I was using a piece of wire with a loop at the end to scoop small amounts out and place into a flame and get small flashes and poofs of smoke. It was great fun until the wire got hot and when I dipped it into the vial of flash powder. WHOOSH! A blinding white flash exploded the vial but not before a jet of fire shot out and completely torched the thumb and finger holding the wire.

I ran to the washroom to rinse off the melted chemical on my skin, I peeled it off and realized this was not melted chemical but actually cooked skin. It was leathery in texture and the burn itself was a deep hole in my finger.

Very painful, took forever to heal and the wound kept sticking to the bandages which added to the nightmare.

Lesson learnt. Don't dip hot metal wires into flash powder and expect nothing to happen

Texium - 7-6-2021 at 05:38

Quote: Originally posted by BauArf56

on SM there a lot of different stories from different users about failed experiments, stupid things done during an experiment, improvised apparatus, experiments done as teenagers and so on. I thought that a thread about these stories would be great, so one doesn't have to search into different threads

To that end, I’ve merged it with an existing long thread that already serves that purpose well.

To add my own recent story… A few days ago, my friend at work was running a column. He had the compressed air line clipped in place, but the clip failed, causing the glass adapter to pop out, ruining his column as the sudden change in pressure caused the packed silica inside to expand and mix together. The adapter swung like a pendulum, directly into a 250 mL Erlenmeyer flask, cleaving it cleanly in half. The fritted funnel that was sitting in the flask fell out and broke into many pieces on the bench, and the silica gel that was inside of it became dispersed all over the inside of his hood that he had just got done cleaning that morning.

Sulaiman - 7-6-2021 at 06:28

Quote: Originally posted by Fyndium

... The hand mixer, although being otherwise good, is very noisy and obviously overpowered. Having 500W of power...

The motor is a simple brushed dc type so can be used with a low voltage dc supply, allowing slow speed while maintaining full torque availability if required.
eg one of my crappy videos https://www.youtube.com/watch?v=ziRxiFSaZsA

Oxy - 7-6-2021 at 09:48

Sulaiman, making the stirrer from hand mixer is really good idea. I definitely need it and will do it also.

Brushed motor can be a problem when working with flammable vapours but the risk can be reduced by enclosing the motor in casing. Need to check if how much heat will it generate and if isolation will not cause any issues. Motor can be also moved somewhere and the force can be transferred via belt.

j_sum1 - 26-6-2021 at 21:43

Leaking glass joint in chlorine generator. Annoying and unpleasant.

draculic acid69 - 26-6-2021 at 21:48

Hope it was noticed quickly and dealt with before it caused unpleasantness

j_sum1 - 27-6-2021 at 04:44

Quote: Originally posted by draculic acid69

Hope it was noticed quickly and dealt with before it caused unpleasantness

Well, the good thing about using an addition funnel sliwly dripping as that you can just turn off the acid and let the production die down. Then the only thing to deal with is the gas in the volume of gas in the system. So, it's not out of control. But it does mean stopping what you are doing.

A bit of teflon tape does wonders. In this particular case it helps a lot to fix the right joint though. Hence the post.

For those who want a useful takeaway...
I keep a spray bottle of sodium thiosulfate solution in the lab. Really useful when working with oxidisers: including cleaning up permanganate spills.
This time around, a squirt on the joints helped diagnose the problem. The droplets go cloudy when exposed to Cl2.

D'oh !

Sulaiman - 12-10-2021 at 00:09

I just received two new thermometers, 0 - 50 and 0 - 100 red alcohol.
I decided to calibrate them against water and my two mercury thermometers.

melting ice ..... all read 0C
boiling water .. POP! ... D'oh! ... 50C thermometer did not like 100C

how dumb/careless of me.

A mildly bad, but frightening day in the lab

aab18011 - 17-12-2021 at 02:51

About 5 weeks ago, we were doing a Grignard. I was helping in the lab because I had finished the day before, and my TA was not feeling well. I was overseeing these two female students who put way too much magnesium in the flask, as in they put an extra 5g whereas the reaction called for 0.5g total (microscale). I didn't stop them because they had already put the ether in and started the reaction, before I realized; I told them to make sure to keep the amount of ether in the flask constant and to add extra if any accidentally boiled out. Long story short, they lost most of the ether and didn't replenish it. Also, remember that this is supposed to be a gentle reflux.

The problem in this reaction didn't arise until the final step of quenching. I had walked away to help another pair of students. At some point, both of the girls screamed and ran to me, absolute hysterics. I quickly ran to their hood to find it full of flames. Not only did it catch fire because they added water to a practically etherless reaction flask, but they dropped it out of fright and it broke onto the bench. They had paper towels all over because they spilled so much water but left a huge clump of dry towels which caught on fire. They also happened to leave a beaker full of ether out because they measured out way too much for the reaction. That too caught fire.

Luckily, the extinguisher was close, and the fire was put out quickly. The part that scared me was the fact that I have not ever seen a fire like that. I have made caught my floor at my lab at home on fire, but on a concrete floor with nothing around to burn. To see magnesium boiling water and on fire with a flask burning and paper clumps puffing out black smoke was frightening. Maybe I am a bit weak, but it shook me and made me more aware of some of my lazy habits when working at home. I have changed a few of my habits immediately afterwards.

oceandeep67 - 12-1-2022 at 03:27

Quote: Originally posted by itsallgoodjames

Quote: Originally posted by Fyndium

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]

oceandeep67 - 12-1-2022 at 03:31

My apologies^

oceandeep67 - 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!

A particularly bad week (or two)

BAV Chem - 26-3-2022 at 01:56

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:

B(a)P - 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.

arkoma - 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.

B(a)P - 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.

arkoma - 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.

B(a)P - 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.

j_sum1 - 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.

wg48temp9 - 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.

j_sum1 - 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.

Lionel Spanner - 6-5-2023 at 03:30

A little while back, I attempted to prepare sodium nitrite by hydrolysing bronopol with caustic soda. As far as I'm aware there is no written record of this procedure, so I was working entirely blind.

On the first attempt I tried adding caustic soda to an aqueous solution of bronopol, which caused a runaway exotherm, making it boil over and spill hot greasy orange water everywhere.

On the second attempt I pre-dissolved caustic soda in water and slowly added bronopol to it, while keeping the temperature fairly constant. This worked perfectly, producing a yellow solution. My intention was then to heat the solution to reflux, but on heating, as the mixture reached about 70-80 °C it darkened from pale yellow to orange and heated up very rapidly, causing the solution to boil, and a runaway exotherm occurred again, violently ejecting a jet of hot greasy orange water through the condenser.

Fortunately I was using a long Allihn condenser, and I'd instinctively removed the heat and moved far from the apparatus as soon as I saw it starting to boil, so no damage was done other than a load of annoying greasy orange stains.

To add insult to injury, once the remaining solution had been refluxed, I couldn't separate the organic products by extraction with ethyl acetate, as it was miscible with them, and the dark red colour of the solution made any kind of phase separation impossible to discern.

beta4 - 3-2-2024 at 02:33

It was cold outside so I tried stick welding in the chemical fume hood.
I thought the aspirator could get rid of the fumes and the tiles surface is fire proof.

Don't. The slag sprayed when welding etches the glaze of the tiles leaving permanent black spots.

Lionel Spanner - 21-2-2024 at 14:06

I recently tried repeating a procedure I'd previously had success with six months ago - reduction of GABA to its alcohol - with the idea of making a video about it.

The first step was heating it with finely powdered sodium borohydride in dry THF until they form an acetoxyborohydride salt. Both are insoluble in THF and the reaction is otherwise very slow, so the mixture needs to be heated nearly to reflux.

At reflux, everything was going smoothly for the first few minutes, until the mixture started boiling vigorously, a load of smoke (dust?) was ejected through the condenser and the suspended white solids in the mixture started turning brown, orange and pink. This has not happened before, and it's fair to say the reaction was ruined, so I abandoned it and later recovered the THF by distillation - that stuff's not cheap.

It had been six months since I'd last carried out this procedure, and the temperature had not quite been as high - 50 °C rather than 65 °C. It's possible GABA had drawn water from the air in the container during that time, and/or a self-cyclisation reaction occurred at the higher temperature, forming the lactam. Either way, it's not doable with GABA straight out of the jar.

[Edited on 21-2-2024 by Lionel Spanner]

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