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Author: Subject: When Chemistry Goes Wrong
Ubya
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[*] posted on 3-11-2018 at 11:05


[rquote=549217&tid=63645&author=CobaltChloride]Wait, even concentrated NaOH eats PTFE? AFAIK, only molten very reactive metals (like sodium) react with PTFE to make metal fluorides, while strong bases do not. [/rquote]

my bad, don't know why i remember NaOH can corrode PTFE:o





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DraconicAcid
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[*] posted on 3-11-2018 at 14:11


I seem to recall reading that molten sodium hydroxide will attack teflon if it's wet. If it's perfectly dry it's fine.



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[*] posted on 4-11-2018 at 09:49


Teflon melting temp: 327°c
NaOH melting temp: 318°c

:P
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[*] posted on 4-11-2018 at 11:18


[rquote=549527&tid=63645&author=Herr Haber]Teflon melting temp: 327°c
NaOH melting temp: 318°c

:P[/rquote]

This a vague-ish memory from a paper I wrote on using molten salts as solvents. I might have been thinking of a eutectic of NaOH/KOH. Or I might be blithering- if I still had a digital copy, I wouldn't have a program that would read it.




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[*] posted on 4-11-2018 at 11:22


Teflon isn't terribly stable at temperatures that high. Which is the main reason it's not feasible to use injection moulding of PTFE.
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[*] posted on 5-11-2018 at 10:24


I've heard that molten lava might attack some strands of wild teflon, but I'm not sure I can trust those sources
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[*] posted on 7-11-2018 at 03:11


[rquote=549855&tid=63645&author=kulep]I've heard that molten lava might attack some strands of wild teflon, but I'm not sure I can trust those sources[/rquote]

lol - yea - molten lava 'attacks' most things I think.




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[*] posted on 13-11-2018 at 06:56


[rquote=549855&tid=63645&author=kulep]I've heard that molten lava might attack some strands of wild teflon[/rquote]

I had to look that up as it goes... I found nothing. What is 'wild' Teflon? Are there cases of PTFE being found in nature then? I was not aware and can find nothing about it.




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[*] posted on 16-11-2018 at 13:51


when I ran a lab years ago, I ended up running into all sorts of problems with stuff unexpectedly blowing up, shattering, or just nearly gassing the house with chlorine after an earthquake knocked over my HCl, which was the first time my lab was raided! Lucky I knew the police because otherwise, things would've ended very differently, and chances are I would've never made a post again.


First point I think is very important to say, if you're on a budget, for the love of all that's good, don't work anywhere near old tools. acid fumes can make the lead paint into a form which will go right through skin. That's exactly what happened to me in an old post I made where I showed my nails, which in fact did have Mee's lines on them. I had a sample sent to a toxicology lab at the request of my doctor and it gave a strong positive for lead and a weak positive for arsenic.

As for what I was working with at the time, don't ask. I still have very deep regrets over my old lab despite having no involvement in drugs or any significant quantity of explosives. Got into a ton of trouble over that thing. Still has a very strong negative effect over my family dynamics and mental state to this day even though I've not even been near a bottle of acid in well over 2 years, let alone a home lab.

My lesson to all of those who are reading this, please don't use home chemistry as a means of coping with a mental disorder. I wasn't in the right state of mind and although my lab worked to get me through school, it also destroyed me in the process, shattering most of my passion for everything and taking away any amount of joy I had in life.

One reason I am online as much as i am under the jersey rebel and roguemillenial is to prevent others from suffering the same fate as me. It's one of the few things that makes me feel as if I've contributed anything to any scientific field :(




Water is wet, fire is hot, I'm a jersey born rebel

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[*] posted on 19-11-2018 at 06:06
Plastic keck clips, understand fire extinguishers


During a nitric acid synthesis the plastic keck clip holding my condenser to the clausin adapter cracked. New hot nitric acid dripped into the mineral oil the boiling flask was submerged in and instant fire.

The fire extinguisher was right at hand and the blaze was out in less than ten seconds.

There was 900 ml of 95% sulfuric acid in the now cracked boiling flask along with the nitrate (potassium as I recall). The hot acid and oil fumed for more than ten minutes. The fume hood exhaust roared a bit (jet sound) and this filled my neighborhood with a dense white cloud. I was very pleased this [b]didn't[/b] bring a visit from the local constabulary.

Two take aways... Plastic Keck clips, never again! Ten pound fire extinguisher... much more mess than the fire! Clean up took more than a day. I am also very careful choosing heat sources and try to avoid oils when possible.

I now use metal clips and have small 32oz sized extinguisher along with a larger ten pounder. In the case of this fire, as impressive as it was, the smaller extinguisher would have worked fine and cut clean up in half. I only used one small blast of the that larger extinguisher and it had to be replaced (refilling them is a hit or miss proposition in my burg).

If you haven't used a fire extinguisher, it would be helpful to at least watch a video of the one you purchased being used (or one much like it). I was very surprised at the volume of material ejected with a small squeeze of the trigger, and the force it came out with is worth considering. This will blow stuff around in most small fume hoods, easily blew my distillation setup half off the hot plate.
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[*] posted on 19-11-2018 at 09:23


[rquote=554173&tid=63645&author=JScott]During a nitric acid synthesis the plastic keck clip holding my condenser to the clausin adapter cracked. New hot nitric acid dripped into the mineral oil the boiling flask was submerged in and instant fire.

The fire extinguisher was right at hand and the blaze was out in less than ten seconds.

There was 900 ml of 95% sulfuric acid in the now cracked boiling flask along with the nitrate (potassium as I recall). The hot acid and oil fumed for more than ten minutes. The fume hood exhaust roared a bit (jet sound) and this filled my neighborhood with a dense white cloud. I was very pleased this [b]didn't[/b] bring a visit from the local constabulary.

Two take aways... Plastic Keck clips, never again! Ten pound fire extinguisher... much more mess than the fire! Clean up took more than a day. I am also very careful choosing heat sources and try to avoid oils when possible.

I now use metal clips and have small 32oz sized extinguisher along with a larger ten pounder. In the case of this fire, as impressive as it was, the smaller extinguisher would have worked fine and cut clean up in half. I only used one small blast of the that larger extinguisher and it had to be replaced (refilling them is a hit or miss proposition in my burg).

If you haven't used a fire extinguisher, it would be helpful to at least watch a video of the one you purchased being used (or one much like it). I was very surprised at the volume of material ejected with a small squeeze of the trigger, and the force it came out with is worth considering. This will blow stuff around in most small fume hoods, easily blew my distillation setup half off the hot plate. [/rquote]

Get yourself a CO2 fire extinguisher, zero residue and you almost WANT to find a reason to use it.
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[*] posted on 20-11-2018 at 17:35


Today I generated several moles of nitrogen dioxide in a few minutes in a tiny makeshift fume hood. That was definitely not a very good idea. As I stared amazed at the huge blob of brown gas sitting inside the fume hood, I decided to adjust the intake to pull out more of the gas more easily. So I flipped the front cover open.

[i]When your fume hood is full of nitrogen dioxide gas, do not open it.[/i]

I backed away from the horrible choking mess with my eyes burning, barely able to breathe, and the hood sealed itself. Eventually, it cleared.

[Edited on 21-11-2018 by JJay]




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[*] posted on 20-11-2018 at 18:01


[rquote=554213&tid=63645&author=Deathunter88][rquote=554173&tid=63645&author=JScott]During a nitric acid synthesis the plastic keck clip holding my condenser to the clausin adapter cracked. New hot nitric acid dripped into the mineral oil the boiling flask was submerged in and instant fire.

The fire extinguisher was right at hand and the blaze was out in less than ten seconds.

There was 900 ml of 95% sulfuric acid in the now cracked boiling flask along with the nitrate (potassium as I recall). The hot acid and oil fumed for more than ten minutes. The fume hood exhaust roared a bit (jet sound) and this filled my neighborhood with a dense white cloud. I was very pleased this [b]didn't[/b] bring a visit from the local constabulary.

Two take aways... Plastic Keck clips, never again! Ten pound fire extinguisher... much more mess than the fire! Clean up took more than a day. I am also very careful choosing heat sources and try to avoid oils when possible.

I now use metal clips and have small 32oz sized extinguisher along with a larger ten pounder. In the case of this fire, as impressive as it was, the smaller extinguisher would have worked fine and cut clean up in half. I only used one small blast of the that larger extinguisher and it had to be replaced (refilling them is a hit or miss proposition in my burg).

If you haven't used a fire extinguisher, it would be helpful to at least watch a video of the one you purchased being used (or one much like it). I was very surprised at the volume of material ejected with a small squeeze of the trigger, and the force it came out with is worth considering. This will blow stuff around in most small fume hoods, easily blew my distillation setup half off the hot plate. [/rquote]

Get yourself a CO2 fire extinguisher, zero residue and you almost WANT to find a reason to use it. [/rquote]

I use Halon / CO2

Halon 3.jpg - 235kB
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[*] posted on 21-12-2018 at 16:22


A very good idea!

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[*] posted on 7-1-2019 at 06:15


I don't think I am very good at making dioxane.

I had a whole string of mishaps tonight. Some amusing.
As I indicated, I think there is something seriously wrong with the dioxane I synthesised from antifreeze. It reacts with NaOH to form a tarry substance. It boils too low. And it reacts with sodium. I think it is more than just a bit of water in it. But anyway I had a small amount that I had redistilled and thought I might try my luck at isolating some Na from Mg/NaOH thermite. Fun times.

1. I used a cast iron pot with lid for the thermite. Part of the product was a very fine powder clinging to the lid. That was pyrophoric. Interesting, and not expected.

2. Dropping a few lumps of the mixture into a flask of so-called dioxane: about 25mL, there was a bit of fizzing of H2. Kind of expected since I suspected that fraction was not completely dry. Later, while tidying up a bit I stoppered the flask. All bubbling had stopped and I did not think much of it. Even later, I picked it up to move it somewhere else and the stopper flew 3 feet in the air and right across the bench. It singled out the one piece of glass at that end of the bench and smashed into tiny pieces. The only good news is that particular item was already broken and I had gotten it out for photographing and measuring so that a replacement could be made.

3. I decided not to leave a container of pyrophoric sodium powder unattended in my lab overnight. After stirring it actually caught alight a second time. I took it outside to burn out. That looked pretty. I then decided to douse it with water from a distance of several metres. Some nice fireworks. That was actually pretty cool.

Ultimately I have nothing to show from a mole of Na and several hours of dioxane preparation. Not unless you count a shattered stopper for an antique iodine flask.
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[*] posted on 7-1-2019 at 09:46


In my experience PTFE reacts with Sodium Hydroxide at dull red heat to form Sodium Fluoride, Sodium Carbonate and formaldehyde which instantly burns. This was tape on molten hydroxide so maybe the leidenfrost effect increased the effective reaction temperature.
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[*] posted on 7-1-2019 at 13:59


Sometime ago I was recrystalizing some AgNO3 and I allowed it to cool on the fridge. Someone opened the door and an extremely corrosive AgNO3 solution spilled all over the place, staining the fridge, the dishwasher, my grandma and me.

Lesson: be aware that other people exist.

The good thing was that I discovered a non-toxic remedy for AgNO3 stains.
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[*] posted on 8-1-2019 at 08:26


[quote]The good thing was that I discovered a non-toxic remedy for AgNO3 stains.[/quote]
You did?

Pray tell...

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[*] posted on 8-1-2019 at 10:37


[rquote=579326&tid=63645&author=hissingnoise][quote]The good thing was that I discovered a non-toxic remedy for AgNO3 stains.[/quote]
You did?

Pray tell...

[/rquote]
@Felab, so you know how to remove the stains from my skin?????
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[*] posted on 15-1-2019 at 06:01


[rquote=579373&tid=63645&author=morganbw][rquote=579326&tid=63645&author=hissingnoise][quote]The good thing was that I discovered a non-toxic remedy for AgNO3 stains.[/quote]
You did?

Pray tell...

[/rquote]
@Felab, so you know how to remove the stains from my skin????? [/rquote]

You take some steel wool (the one that is used for polishing wood, not for washing dishes) and soak it in 3% H2O2. Toothpaste can be mixed with the H2O2 for better consistency. The thing will warm up and fizz. You rub it on your hands for a good while and your stains will be gone or much lighter than they where. If the steel wool starts cooling down and your stains aren't gone, soak it in fresh H2O2/toothpaste solution. It is what I usualy do when I get stained.

[Edited on 15-1-2019 by Felab]
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[*] posted on 10-2-2019 at 08:06


I dip a cloth in a strong thiosulfate solution and rub. It takes some effort to get the stains off, since they are elemental silver, but the silver chloride complexes with the thiosulfate and dissolves. If you get AgNO3 on your skin, do this before the resulting AgCl has a chance to see much light - you can prevent stains from happening in the first place.

To get the stains off quickly but non-safely, you can apply a little nitric acid directly to your skin and then wash it off within a few seconds, before a burn forms. But the thiosulfate is recommended. ;)
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[*] posted on 16-2-2019 at 20:48
The Formation of Explosive Diurea From Potassium Iodide And Permanganate


So, as I've mentioned before, I use a Thames and Kosmos C3000 chemistry set as part of an educational program. Yesterday, I tried experiment #134, producing a solution of iodine in denatured alcohol. Everything was set up according to these instructions:

[file]73823[/file]

Note: 'spoonful', 'small spoonful', and 'permanganate mixture' mean .3 to .5 ml of dry powder, at most .1ml dry powder, and a mix of 1 part KMnO4 to 2 of Na2SO4, respectively.

Before the flame was even applied, the solution of KMnO4 and KI started to turn dark green and opaque, suggesting the formation of manganate. On heating, the mix boiled and became even darker. A lot of water condensed in the angled tube, and fell into the denatured alcohol. A few dry particles of permanganate were wetted creating purple droplets in the heated test tube, but the promised purble iodine vapors didn't appear.

Well, I thought, there was a reaction, so there [i]has[/i] to be elemental iodine in the mixture. If I can just boil all the water off, it will get hot enough to make it evaporate. When most of the water was boiled off, it bumped forcefully. Most of the thick brown goop (a lab partner described it as "shitty") stuck to the sides of the test tube, and a drop made it into the angled tube. I stupidly decided to start dry distilling what was left at the bottom. No purple vapors were visible. At this point I lifted the angled tube out of the alcohol test tube , and put the reaction tube upright, to make the paste fall back to the bottom.When it fell, thermal shock cracked the test tube, although it wasn't visible until I was trying to clean out the tube. Heating the paste at the bottom of the tube did nothing as far as creating iodine. Also, while I was cleaning the reaction products (manganese hydroxides?) out of the tube, the cracked bottom fell off. In over 100 experiments, this was the first piece of glassware from the kit to break. I guess it's 'idiot resistant', not idiot proof:D

The next experiment involved KI in a divided electrochemical cell. Two cups were connected, as per rhe instructions, with a wide strip of paper towel. With the specified power source (9v) the current was about 200μA, and no visible iodine formed. I decided to just put both electrodes in one compartment, and when some iodine formed near the anode I pulled it out, and rinsed it in the other cup. Soon I had the other cup full of a weak iodine solution, much better than anything from the high resistance divided cell, or the permanganate experiment.

Just before writing this long winded story, I looked in the chem. set booklet again and found this:



[file]73825[/file]

Note that next to the drawing it also says to use sodium hydrogen sulphate, not just water, potassium iodide, and potassium permanganate. The written instructions said nothing about this crucial addition. But even if I had seen this before, it doesn't say how much to add, anywhere.

TL;DR I tried an experiment (demonstration, actually) from a chemistry set, the write-up had an error, and instead of making iodine solution, it made a slimy brown mess (see title) and a broken test tube.

The kit has proven to be full of reasonable quality equipment and interesting and informative reactions, but I may write for them to correct this error.

[Edited on 17-2-2019 by Vomaturge]

P_20190216_185604-640x360.jpg - 67kBP_20190216_185621-640x360.jpg - 42kB
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[*] posted on 17-8-2019 at 18:59


One of those, "what the hell was that" moments.

Some time ago I picked up my container of barium chloride (original packaging) to find a small crack in the bottom and a spill of white powder. Obviously a need to transfer to a new container. I swept up the spill to dispose of it properly. It was probably less than a gram in total, but I like playing cautiously with barium compounds. My standard procedure for these kind of things it to convert it to an insoluble form and mix it with cement and sand to form a cement block that I can dispose of as solid waste. So I mixed up some magnesium sulfate solution and added it to the beaker containing the swept material.

And left it there. For several months.

Or so I thought.


Today I needed a clean beaker, which meant that a clean-up was overdue. I proceeded to add sand and cement to what I thought was this offending barium waste to make my concrete block. After addition of water I was greeted with the unmistakable waft of hydrogen sulfide and considerable bubbling.

I think I must have cleaned up the barium earlier. But what the hell was in that beaker that would cause H2S on the addition of cement?




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[*] posted on 17-8-2019 at 21:47


I do not know what was in the beaker but the incident is a reminder to
HAVE A LAB NOTEBOOK AND KEEP IT UP TO DATE :P




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[*] posted on 18-8-2019 at 08:30


The first question is what is your BaCl2 really and how much did you pay for it. I've mentioned getting a big surprise from some cheap BaCO3. Both of these are made from BaS obtained by reduction of barite.

The second question is why "BB Code is Off" in this thread?

[Edited on 18-8-2019 by S.C. Wack]




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