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Author: Subject: When Chemistry Goes Wrong
Melgar
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[*] posted on 9-11-2017 at 21:09


Quote: Originally posted by TheNerdyFarmer  
Yesterday I decided to generate some ammonia gas for a separate project of mine. I had the whole gas generating setup built and so I mixed the reactants and started gas generation. By the way I was making ammonia via ammonium halide salt + alkali metal hydroxide. Any way, the reaction started and a lot of gas was coming off. There was also a good deal of moisture coming with it. Little did I notice that some (a great deal) of ammonia gas was leaking from the tubing that I used to make the gas generating setup. Before I realized what was happening I lifted the sash of the fumehood up and got a huge whiff of ammonia gas. I had forgotten to turn my fume hood on. I quickly turned it on and ran to the other side of the lab. I walked over to the hood every few seconds and within 2 minutes there was no detection of ammonia gas.
This wasn't a super dangerous situation but it did give me somewhat of a scare considering that ammonia isnt the greatest stuff to inhale.

[Edited on 6-11-2017 by TheNerdyFarmer]

I kind of like the smell of ammonia, because I've come to associate it with neutralization of HCl vapors. I did this one halogenation reaction a lot that necessitated generating chlorine gas, and produced HCl gas. Both gases escaped from time to time, and opening my ammonia jug and squeezing it repeatedly to get the vapors to diffuse would allow me to see where the bad vapors were coming from and stop them. It reacts with Cl2 and HCl in midair to generate salts, which are visible like smoke.

Incidentally, if you want to generate anhydrous ammonia gas cheaply, the most effective way I know of is heating urea to about 200C. It's super easy to control; you just turn the heat up or down. It leaves cyanuric acid residue, which you can use to make cyanates or any number of things. It's hard to clean out of stuff, but will form isocyanuric gas at higher temperatures.




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NedsHead
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[*] posted on 9-11-2017 at 22:05


I managed to contaminate my nitre bluing tank with copper and nickel ions, it's a small pot that I use for bluing tools, about 2 litres containing approximately 1 mole potassium nitrate and 1 mole potassium hydroxide, I could use some advise on how to go about removing these impurities.
Thanks
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ninhydric1
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[*] posted on 9-11-2017 at 22:12


@NedsHead I would assume that the hydroxide ions from the KOH would precipitate the copper and nickel ions from solution. Maybe wait and see if any precipitate settles to the bottom of the bluing tank?



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[*] posted on 9-11-2017 at 23:21


Thanks ninhydric1, I made a solution of the bluing salts and was able to filter off the precipitate, it looks to be mostly copper.

below is a picture of the failed part to be blued, it's the components to a vernier height gauge




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[*] posted on 10-11-2017 at 00:28


Could you attempt to plate out soluble metal ions with carbon electrodes and then filter or decent your solution. Set it aside long enough to get the pot clean? I can't say I have tried this, but I would think it might have a chance. Not sure if you want to use the pot as an electrode, cathodic protection or no. Graphite battery rods and a usb hookup 5v between them may just be easy enough to try for a few min, with little setup effort. If it works awesome, if not no huge loss.

I did a quick search on that bluing, it had water in the mix, ie. per gallon directions. Yours is the same ya? Or just salts melted when needed for dipping? Pretty sure I have seen hot dipping that included no water, on you tube. That would be less fun, and possibly a poor memory so incorrect.





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TheNerdyFarmer
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[*] posted on 10-11-2017 at 05:55


Quote: Originally posted by Melgar  
Quote: Originally posted by TheNerdyFarmer  
Yesterday I decided to generate some ammonia gas for a separate project of mine. I had the whole gas generating setup built and so I mixed the reactants and started gas generation. By the way I was making ammonia via ammonium halide salt + alkali metal hydroxide. Any way, the reaction started and a lot of gas was coming off. There was also a good deal of moisture coming with it. Little did I notice that some (a great deal) of ammonia gas was leaking from the tubing that I used to make the gas generating setup. Before I realized what was happening I lifted the sash of the fumehood up and got a huge whiff of ammonia gas. I had forgotten to turn my fume hood on. I quickly turned it on and ran to the other side of the lab. I walked over to the hood every few seconds and within 2 minutes there was no detection of ammonia gas.
This wasn't a super dangerous situation but it did give me somewhat of a scare considering that ammonia isnt the greatest stuff to inhale.

[Edited on 6-11-2017 by TheNerdyFarmer]

I kind of like the smell of ammonia, because I've come to associate it with neutralization of HCl vapors. I did this one halogenation reaction a lot that necessitated generating chlorine gas, and produced HCl gas. Both gases escaped from time to time, and opening my ammonia jug and squeezing it repeatedly to get the vapors to diffuse would allow me to see where the bad vapors were coming from and stop them. It reacts with Cl2 and HCl in midair to generate salts, which are visible like smoke.

This is clever. I have never thought of using ammonia to detect HCl. I will certainly try this in the future. Thanks for the tip!

Incidentally, if you want to generate anhydrous ammonia gas cheaply, the most effective way I know of is heating urea to about 200C. It's super easy to control; you just turn the heat up or down. It leaves cyanuric acid residue, which you can use to make cyanates or any number of things. It's hard to clean out of stuff, but will form isocyanuric gas at higher temperatures.


I will definitely try this method next. It seems cheap and does not generate a ton a moisture like the other reaction did.

Using ammonia to detect HCl is pretty clever. I don't know why i have never thought of using ammonia to detect HCl before. I will certainly try this in the future. Thanks for the tip!

[Edited on 10-11-2017 by TheNerdyFarmer]
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Melgar
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[*] posted on 10-11-2017 at 10:17


Quote: Originally posted by TheNerdyFarmer  
I will definitely try this method next. It seems cheap and does not generate a ton a moisture like the other reaction did.

When I first did this reaction, it was for the purpose of generating potassium cyanate by heating a mixture of potassium carbonate and urea. This reaction was generating enormous volumes of gas, to the point where I had to move everything out of the shop. It just kept going, and going, and going. Granted, it would have been both CO2 and NH3, but in either case, you'd be getting one gas molecule for each parent molecule. It was annoying at the time, but then I remembered that reaction at one point later when I actually did need to generate NH3 gas, and used that instead of the typical "ammonium salt plus a strong base" method. Far superior, in my opinion, and it's much easier to get full conversion without adding undesired water to the mixture. You may need to use a dryer tube or something, because I don't think urea is typically anhydrous, (I could be wrong though) but there won't be nearly as much water as the way you were doing it.

Quote: Originally posted by TheNerdyFarmer  
Using ammonia to detect HCl is pretty clever. I don't know why i have never thought of using ammonia to detect HCl before. I will certainly try this in the future. Thanks for the tip!

Note that the resulting salt clouds will set off smoke detectors, and leave white film on glass. But it sure is better than the rust patina that results from escaped HCl and Cl2 gases. Obviously, you can also use HCl vapors to track NH3 vapors. For either one, I have squeeze bottles of HCl and NH3 solutions, and I just squeeze the air out of them repeatedly to generate small amounts of vapor when I need it.

There should be a "Tips learned through experience" thread. I'm actually surprised there isn't one.




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[*] posted on 17-11-2017 at 15:38


Every time I've made an ester I've had low yields, usually in the 50-60% range. Recently I was making diethyl phthalate, and I was determined to get a high yield. I used a large excess of dry ethanol and 3A molecular sieves in a soxhlet, after distilling off the extra ethanol all traces of water had essentially been eliminated. I mixed the residue with water to wash out EtOH and H2SO4, which left a dense oily liquid with a volume of a little more than a quantitative yield. Next I washed with NaHCO3 solution. The first three or four times shaking built up pressure but not too much. Then I shook the sep funnel again, but this time it built up a lot of pressure. Enough to push out the stopper (which I was holding firmly in place) and allow much of my product to be sprayed out onto the bench :(

Looks like another low yielding Fisher Esterification...

Hmmm I don't think high boiling liquid will be easy to clean from wood.




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[*] posted on 17-11-2017 at 15:59


One day in the school lab, we were preparing methyl salicylate as an intro to esterification. Dissolve salicylic acid in methanol, add a few drops of conc. H2SO4, reflux for 10 minutes, then smell - definitely the expected Deep Heat odour. Following the procedure, which for us seemed to fail more than succeed, we all dumped in some cold water. Out came the salicylic acid faster than it had formed, still smelling of the ester so that threw off most of my classmates but I had done my homework before and figured it wasn't the product we had hoped for since it was a solid and not the liquid that melts at -8C.

Moral of the story, keep water well away from esters that are in contact with an acid!




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[*] posted on 17-11-2017 at 16:19


Hydrolysis isn't very fast at room temperature. Otherwise you wouldn't have to reflux the mixture to reach equilibrium. 10 minutes was much too short, did the procedure actually call for that? I would relfux for a least an hour, for example I let my diethyl phthalate go for two hours.



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[*] posted on 17-11-2017 at 17:57


We're only talking small scale here, I don't have my lab book anymore but I believe we used about 2g of SA and around 20mL of methanol. The procedures, which were ironically designed for education, had some pretty glaring errors and were commonly inaccurate - this particular one actually suggested that the methyl salicylate was a solid product and to use a melting point apparatus to determine purity. Had to follow them fairly closely, they're designed to be conducted within an hour lesson and that includes a preliminary assessment, setting up the apparatus, carrying out the procedure, and work up which explains why times were so short. Otherwise I certainly would've refluxed for longer, I'm guessing a lot of what dropped out was just dissolved in the methanol but the ester was almost overpowering, tingled the nose a little and this was reduced to a faint scent after water was added.



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[*] posted on 18-11-2017 at 00:53


Nedshead: Leaving some scrap steel in the solution should plate out any dissolved Cu/Ni. From the pic it looks like this is what happened to your part.
Is the bath aqueous (caustic black) or molten salt? I use two parts by weight of NaOH and one part Na/KNO3, adjusted to a BP of appr 135°C. Some recipes call for nitrites, but it works fine without. Besides nitrites should form in situ as the iron is oxidized.




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[*] posted on 20-11-2017 at 06:09


Yesterday: Combined Pb metal and Glacial Acetic acid in a beaker. Added concentrated Peroxide. Stirred mixture. Nothing happened. Added all of the concentrated Peroxide. Mixture began to boil. Panic set in. Ran outside, carrying the boiling mixture in the beaker. Hastily decanted the liquid into another container. Got a face-full of Acetic acid vapor. Gave up on Chemistry for the day and went to get a cold one.


Fin.




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[*] posted on 21-11-2017 at 00:23


Hey VS, I'll dilute some and run a test to try plate it out with carbon electrodes as suggested, Thanks.

The formula I use does call for water but I got tired of controlling the evaporation so just let it become a block of solid salts and used it that way.






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[*] posted on 30-11-2017 at 05:16


Decided to make some chloroform and as I am without a fumehood (next thing on the list) I thought I'd place the bleach bottle containing the reactants in my tiny bathroom area as it's the only place in my tiny shoebox of a living space with some sort of extraction fan, plus I could place the bottle in the shower area and close the glass shower door to further contain the chloroform fumes.

Of course if I wasn't a complete moron I would have put the bleach bottle and the ice-bath it snugly lived in fucking outside possibly? But no, in the bathroom is fine...

Realize well after the reaction is underway that I made a stupid stoichiometric error failing to use not nearly enough bleach. Figuring I may aswell start tomorrow with a brand new bottle of bleach I decide to decant off the top layer of solution in the bottle and dispose of whatever chloroform and unreacted acetone remains in the bottom layer.

Proceed to clumsily spill the shit everywhere mostly managing to contain the spill to the shower area. Fucking fruity smelling chloroform fumes fill the tiny shower cubicle which in my eternal wisdom is closed which would be fine if I wasn't inside the fucking thing... bleach and chloroform all over my hands, the floor and now thanks to the fumes, my face.

Cop enough of the stuff to make spin me out more than just a bit which makes cleaning the stuff rather difficult and greatly reduces my brains ability to realize I should probably get the fuck out of the bathroom. Clean it all up, half-assedly rinse out the bottle and put it under my sink with the lid off to lightly gas that area while I'm asleep...

Go to sleep. Wake up feeling GRIM AS FUCK. Smelt good though... like pine-lime ice blocks! Yum!


[Edited on 30-11-2017 by WangleSpong5000]

[Edited on 30-11-2017 by WangleSpong5000]
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[*] posted on 30-11-2017 at 16:07


Quote: Originally posted by BromicAcid  
My early mistakes can be found here:

http://bromicacid.com/mistakes.htm

For those just looking for the high-points here is a list of the titles:


Neutralization of Sulfuric Acid
Acetone Peroxide
H2SO4 / HNO3
What's In a match head?
Silver Thermite
Phosphorus!
Caustic Nightmare
Chlorinated


The ammount of luck you have is amazing. Next time shit goes sideways go buy lottery tickets.;)
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[*] posted on 30-11-2017 at 17:24


Having read postings on this thread over the last year or so, I propose that it be renamed "When amateur chemists go wrong!"
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