I'm sure most people on this forum have had their occasional "OH SHIT!" moment when an experiment went unexpectedly wrong. Maybe if we share these
then we might not make each other's mistakes.
Here's mine:
Today, after trying just about every imaginable technique to remove an extremely stubborn stain from a surface, I got a bit desperate and decided to
try using permanganic acid. I have potassium permanganate and sulphuric acid, so I figured I might as well give it a go.
Now, I was of course aware that if you use too high a concentration of sulphuric acid, then you get the anhydride of permanganic acid: manganese
heptoxide, a rather dangerous explosive compound. So I check online and read from multiple sources that the maximum safe concentration of sulphuric
acid is 80%.
To be on the safe side, I thought I'd go for a bit lower than that: two thirds = 67% and is a nice fraction so why not. I dilute my drain cleaner,
weigh out some permanganate, and head to the scene of the stain.
Stupidly I dump all of the permanganate into the acid in one go. An exothermic reaction occurs, stronger than I was expecting but not immediately too
concerning.
After a couple of seconds I got to see countless pretty mini explosions. OH SHIT. I realise what I've done and back off as it emits a noxious cloud of
smoke and sparks, and I can see bits manganese dioxide fly everywhere. Ran to the next room to grab some extra PPE. Bloody smoke detector starts
peeping - at least it works I suppose.
At arms length I dumped plenty of cold water into the (still exploding) beaker and everything quickly becomes calm. Thankfully, no injuries, and no
damage to anything. Just a mess of manganese dioxide everywhere.
How did I screw this up, when I knew this was a risk and deliberately tried to avoid it? I made the solution 67% by volume rather than 67% by weight.
Oops.
With the density of sulphuric acid that's quite an error.
I used 91% sulphuric acid drain cleaner, and deliberately neglected the 9% water and other crap. 40ml drain cleaner and 20ml water. The drain cleaner
should have a density of about 1.82 g/ml, so that was 72.8g of drain cleaner. 91% of that is sulphuric acid, so 66.2g. +20g water gives 86.2g total,
66.2/88.2*100= 75% w/w.
Hmm, even with my stupid error, I should have still been safe according to the 80% max claims. Even if my drain cleaner is stronger than it claims, my
solution would still have been under 80%. So it seems that this guideline is inaccurate and unsafe.
Swinfi2 - 1-3-2018 at 18:15
My first reaction outside the uni lab (facepalm)
I realised the jar of what my parents were calling "oxalic acid" wasn't what it was supposed to be when it dissolved some cleanup tissues as i was
trying to eyeball a titration with some bicarb. next step, proof it is what i think it is, yup, most acids don't make carbon snakes . (next step buy scales)
So I thought I'd make some HCl so I can put that under my belt and use it for some other things. everything went great, alright time to clean up.
Then I realised why a suckback trap is so important. my vacuum takeoff adaptor died from a steam explosion. Always use a suckback trap! Luckily nobody
was injured as flying acid coated glass doesn't sound like it would be easy to explain in a hospital.WouldSynthesizeForFood - 1-3-2018 at 21:46
Cleaning glassware with piranha generates these moments too.
The synthesis was simple: get some oleic acid (technical grade), add water, place overhead stirrer in the flask and turn it on while heating the
mixture. Then add equivalent amount of NaOH dissolved in water, let it react and collect the product.
Unfortunately, I've always been too impatient. This time I didn't heat mixture enough and product solidified. Some of it I could scrape out, some of
it could be washed out, but approximately 50 grams of it were still there.
So what do you do if you're impatient? Prepare piranha of course! And few minutes later I was standing near the stand with a warm beaker containing
100 ml of piranha.
Why did I dump it in all at once? I don't know, but the next thirty seconds were as follows: flask contents blackened, warmed up to a boiling point of
a mixture and started moving to the flask necks. Roughly at this point I understood WHAT was about to happen and covered two of three necks with a
beaker standing nearby and moved to a corner of the lab away from the setup.
Meanwhile flask contents started flying out of the uncovered neck on the fumehood, table, walls and everything located there. Next three hours were
devoted to cleaning that mess while swearing liberally.NEMO-Chemistry - 1-3-2018 at 21:49
Dissolving Copper wire in Concentrated Nitric acid, not much happened at first. Really perplexed and figured i been sold dud acid, so stick the large
conical flask on the hot plate and add some heat.
Didnt bother with a stir bar didnt see the point, still nothing after 10 mins so crank the heat up........
Brown gas very suddenly and very dark spills over the top and flows down the sides of the 2 ltr conical flask! No gas mask no hood and inside.
Well as any good noob knows the remedy is simple, neutralize this brown monster with some alkali. Like a good noob I had too on hand and ready, a
container of sodium hydroxide prills and some magnesium carbonate.
At the time I was low on sodium hydroxide, so i was reluctant to use it. So i grab the bag of magnesium carbonate and start pouring it into my pretty
warm nitric acid / copper nitrate solution. WOOSH a fountain of liquid shoots out the top of the flask and down the sides onto my really good hotplate
stirrer.
I unplug it and leave the room, some hours later i return to clean up. Still alot of acid as I doubt i got much carbonate into the flask containing
around 1 ltr conc Nitric acid, i only had a small amount of copper wire as I wanted to avoid the brown monster.
Hotplate dead, various bits or metal like my stands etc are corroded. To compound my noobness at the time i decided to clean up with normal lab gloves
and a really strong hydroxide solution and a sponge and bowl. The end saga was a pair of gloves that lasted a couple of mins, fingers and palms burnt
by hydroxide solution and a thumb, that for some reason was burnt by nitric acid as seen by it going very brown and being very painful.
My chest was bad for 2 weeks i ended up with a chest infection needing anti antibiotics and a cough that lasted 3-4 weeks. Then i joined a chemistry
club at school and got membership here after talking to a good friend who recommended here.
I still do chemistry at his house, i am banned 100% forever from doing it at home. However since then i have been partly responsible for several fires
at his house , but he was also involved....
Only other OMG moment was buying a new gas mask, i didnt know the cartridges they come with are dummies! And the actual ones you use are the ones in
the packet, i assumed those were spares! So i made chlorine happy knowing i had a gas mask on, very quickly did i discover the things that come with
the gas mask are not the actual cartridges but the cases for them......
No bad results but a bit of a bum twitch.LearnedAmateur - 2-3-2018 at 00:12
I’ve got two very recent stories from the same day, just happened to be one of those bad luck occasions.
First off, I had a sodium formate solution that I wanted to try to heat to dryness in a small flask so that I could make a standard solution (didn’t
ever get around to it and you’ll read why). Boiling it down went okay, I held the flask above a flame whilst swirling so that I didn’t need to use
boiling chips, and copious amounts of steam was leaving the top. When the solution reached a small volume, I could see the cloudinesss forming that
indicated I needed to start being more careful with heating since I didn’t want to decrease temperature, and was rapidly forming a powder under the
liquid. It began to get a little thicker and I was literally about to cut the oxygen to the flame (thus I took my concentration away from the flask
and stopped swirling for literally a second), when BANG, the entire contents of the flask ejected from the mouth, over my right shoulder, splattering
moist and hot sodium formate all over the ceiling and wall as a steaming mess - this is why you never point a heating vessel towards anything
important! Cleanup wasn’t too difficult to, luckily just required some wetted kitchen towel to wipe it up and it hasn’t stained anything.
A few hours later, I was trying to neutralise a freshly refluxed solution containing a fairly high concentration of NaOH, and running out of space in
the flask, I decided to switch to using concentrated sulphuric acid instead of 10%. Now everyone knows that sulphuric acid dissolves exothermically,
and also reacts exothermically with sodium hydroxide, so of course combining the two when already hot easily brings water past it’s boiling point
even with a minuscule amount. A few drops came splattering out the flask’s mouth and one landed on my hand, which burned the skin immediately.
Of course, nothing major and just a tiny superficial wound, but it was lucky that I did this drop wise and didn’t dump the rest of the pipette into
the flask during the course of crapping my pants! Another two lessons reinforced, chemistry should never be rushed, and always experiment on a
micro-scale first.
Tsjerk - 2-3-2018 at 02:07
I put some potassium chlorate and red phosphorus on a news paper and moved the paper around to mix the two. I didn't weigh anything and just put some,
about 1:1. It turned out to be around a half a gram which left me with ringing ears and phosphorus burns on my hands when it exploded while mixing on
the paper. My hands had the typical white phosphorus smell too them. Σldritch - 2-3-2018 at 03:52
I think my biggest accident was when i was trying to dissolve two microwave ferrite magnets to extract the strontium from them. I was stirring them,
slightly crushed, with a big glass stirrod in a 1000ml beaker filled with about 800ml of 30% HCl. Suddenly the beaker broke and all of it poured out
on the floor and the stone tile i was using as a bench and dissolved a fair bit of it. Cleaned it up with a lot of sodium hydroxide and got away with
only a minor chough. DavidJR - 2-3-2018 at 07:26
Cleaning glassware with piranha generates these moments too.
...
Some of it I could scrape out, some of it could be washed out, but approximately 50 grams of it were still there.
So what do you do if you're impatient? Prepare piranha of course! And few minutes later I was standing near the stand with a warm beaker containing
100 ml of piranha.
Fortunately I've never done that even though I use piranha solution semi-regularly to clean fritted filters. Though I've always been careful to remove
as much material as humanly possible before resorting to that.DraconicAcid - 2-3-2018 at 12:45
My worst "Oh Shit" moment was when I purposely made dimanganese heptoxide, but then attempted to extract it. From memory, I thought it could be
extracted with carbon tetrachloride or chloroform, so I decided dichloromethane would work just as well. It didn't. Huge cloud of black smoke,
spreading MnO2 all over the inside of the fume hood.
When I checked the reference later, it said "carbon tetrachloride or chlorofluorocarbons".Ubya - 2-3-2018 at 14:24
my worst "Oh SHIT" moment (until now) was when i decided to make some copper
sulphate.
i did it the electrolysis method, and once crystals started precipitating i stopped the current flow.
i evaporated the solution in the kitchen (yes i know, but i was at the beginnings so no fumehood or hotplate), i got pretty bored watching water
boiling so i tought to check every few minutes while i was in my bedroom. so it ended that i got distracted and i forgot the solution on the flame,
all the water evaporated and also the excess sulphuric acid started to evaporate filling all my house in sulphuric acid vapors. i smelled the acid
from my room and realized the mistake, i couldn't breathe, so i had to hold my breath while i opened every window and every door to recirculate fresh
air and vent outside the acid. i used a big playwood panel to fan air out the windows, it was pretty hilarious and scary. i was alone home and my
parents never knew what happened, my lungs were irritated for a few hours thanks to just one or two breath of acid. now i stand carefully watching
everything i do, never leave alone a boiling solutionaga - 2-3-2018 at 14:32
For me my worst "Oh Shit" moment was reading what i'd posted on SM the morning after posting whilst drunk.
It's a bit like Ground Hog Day - happens regularly, if not every day.LearnedAmateur - 3-3-2018 at 01:05
@Ubya, that reminds of the time when I just started getting into chemistry at about age 12 and heard you could make white phosphorus from urine. So
there’s me, home alone, boiling down a jar (at least I was smart enough to not use a saucepan) of about 500mL urine on the stovetop when it starts
to turn brown and smoke, filling the kitchen with acrid and utterly disgusting vapours as well as creating a slight haze. I’m running about trying
to open the windows and fan it out whilst liberally spraying Febreze about to cover my tracks. Really funny now that I look back on it since my
parents were none the wiser but I was quite the little shit at the onset of puberty, surprised I didn’t manage to damage myself in any way.
@aga, that’s me occasionally, I mean I don’t drink regularly but I have been on here several times whilst under the influence and wake up anxious
that I’ve written complete/partial bollocks; I wonder if anyone could tell..Foeskes - 3-3-2018 at 03:31
I once intentionally made Mn2O7 but accidents you put in like 10-20 grams of permanganate. I quickly ran away and my work area looks like a volcano
erupted and was completely black with MnO2.
I contaminated a oxidizer with NaCH3COO so when I dry it in my hot plate it defragated.
I melted some candle wax in a gas stove and put a tiny amount in and cut some more and it suddenly caught on fire and filled the area with smoke.woelen - 4-3-2018 at 10:39
I once wanted to demonstrate the sensitivity of a mix of KClO3 and red P by shing some sunlight on it through a magnifying glass. I demonstrated this
to my children.
I carefully took a few 100's of mg of KClO3 and put this outside on a concrete tile.
Next I took a similar volume of finely powdered red P and put this on the KClO3.
Then I took a little twig (appr. 10 cm length, 3 m thick) from a tree in order to carefully mix the chemicals.
Next, I wanted to take the magnifying glass and show the POOF reaction. This latter part of the demo never occurred. I pushed the little twig in the
mix and moved it a little and sudenly the mix went POOF, spraying around little molten droplets of salts. I had many small burns on my hand, it was
hurting quite a lot.
At least I succesfully demonstrated how sensitive this mix is nitro-genes - 4-3-2018 at 17:56
Made some hydrogen balloons for my kids from NaOH and aluminium, that we would be releasing in the air...great fun. In the name of safety of course...
'cough...', daddy was curious how dangerous exactly lighting one would be. Without much oxygen, I expected it to burn rather slowly, but as I put the
lighter under it it made an earringing "Boom" instead. Problem was that I used a relatively large erlenmeyer to generate the hydrogen gas, and forgot
that the large amount of air present was apparently enough to exceed the explosion limits of hydrogen gas. Next time it will be helium instead.
[Edited on 5-3-2018 by nitro-genes]TheMrbunGee - 4-3-2018 at 21:41
Without much oxygen, I expected it to burn rather slowly, but as I put the lighter under it it made an earringing "Boom" instead.
Apparently hydrogen forms explosive mixtures with air at concentrations between 4% and 75% v/v.VSEPR_VOID - 5-3-2018 at 07:26
I spent a whole day at the lab carefully preparing very pure copper nitrate, in the process using 300ml of 15.6 molar nitric acid, and being in a uch
boiled down my solution. I founder out later when my evaporating dishes were caked in basic copper nitrate, under heat it decomposes.
[Edited on 5-3-2018 by VSEPR_VOID]DavidJR - 7-3-2018 at 10:04
Less dangerous than my previous post but just as much swearing: today, I went to get a spatula full of activated carbon out of the bag. I instead
dropped the whole 1kg bag and instantaneously painted the entire room black...woelen - 7-3-2018 at 13:16
Another "Oh shit" moment was when I made mercury(II) arsenate and dried this chemical.
I made 1 gram or so of solid Hg3(AsO4)2. A neat brown compound, a very fluffy powder.
I put the nearly dry powder on a piece of very smooth teflon, shaped like a dish, with the intent to dry the material further. I pick up the dish from
the table and I hear a faint hissing, like you hear when you rub a balloon over hair or take a highly static pull-over over your head, due to static
electricity. My room was very dry, it was a cold and dry winter day. While I pick up the dish I look at the pile of dry powder and quickly (in a few
seconds) I see the pile of solid spray around until all of it is gone
The cause of this nasty event was buildup of static electricity and this caused the material to be expelled from its heap until all was gone. I never
found any of the solid again, it has been dispersed as a very fine dust in my lab.
When I saw this happen, I really thought "OH SHIT", araid to inhale very toxic mercury and arsenic stuff. I ran away and closed the door tightly.
Several hours later I entered the room with a big wet towel and wiped every horizontal surface in my lab to clean up any dust. I did not see anything
special in the dust I took away, but I am quite sure that it contained some of the mercury arsenate. This happened last winter, one year ago and I had
no adverse effects, but the experience was not fun at all. It was bad that it happened with such a toxic compound,j_sum1 - 7-3-2018 at 14:38
That is one of the scarier stories I have heard from you, woelen.ninhydric1 - 7-3-2018 at 15:44
Mercury and arsenic are two elements you don't want in the same compound. Wonder if thallium or cadmium arsenate would be worse.Vicarious3rdEye2 - 8-3-2018 at 14:31
I was trying to steam distill 1,3-benzodioxole that I made starting from Catechol. My setup was a regular atmospheric distillation setup with a three
necked flask in a heating mantle and I needed to add water to the flask so I started to pour some H2O in the side arm and it basically blew out all of
the contents inside and onto all of my wall, TV, and computer among other things as I decided to do the reaction in my room that day. The thing was
like a cannon filled with mud and then caught on fire all around the inside of the heating mantle and flask. I immediately threw a towel onto the
whole thing and it went out in just a few seconds but the whole side of my room looked like someone was assassinated a foot from my wall except it was
all brown and stunk like hell.
I felt so damn stupid and make sure I remember never to do anything like that again. Firmware21 - 13-3-2018 at 02:53
I technically didn't do this, but it was under my fume hood...
Trying to clean a very dirty but intact flask (with white solid stuff inside) that someone just trashed in the broken glass bin (because the lad was
lazy) using a nitration mixture.
I was going to leave it overnight with conc. sulfuric acid to try and dissolve the white solid mess that was inside it when one of my friends in the
lab came with the idea of using "something stronger" (so I told him to go ahead, when I should have asked what he was going to do). It's only when
there was a massive cloud of NO2 in my hood that I realized it what he did (I was taking an IR spectrum when he added the mixture to the flask under
my hood). Of course, since the lad didn't even bother to add an ice bath, I rushed and extremely quickly prepared one. Fortunately it died down
quickly afterwards.
I learned later that the stuff inside the flask was a mixture of benzamide, benzonitrile and and unreacted phosphorous pentoxide.Velzee - 13-3-2018 at 08:22
About a year ago, I had a mixture of HCl and acetone, I added a small amount H2O2 and panic settled as I realized the predicament I just put myself
in. I in apanic resorted to putting the mixture in the fridge. I went to go check up on it around twenty minutes later, and noticed it was boiling,
and the plastic wrap I had covered it with had developed a US quarter-sized hole. I noticed an odd, pleasant, chlorine-like aroma coming from the
fridge. I closed it, and began to felt like I was going sneeze. The best way I could describe it, was imagine eating a spicy pepper, and the spice
building up. Replace the spiciness with pain, multiply it by a few levels, and that's how my nose was feeling after ten seconds. Tears literally
started pouring out of my eyes as the pain and burning sensation in both my nose, and my eyes, AND my throat was beginning to overwhelm me in a way
I've never experienced in my life. Turns out I accidentally made chloroacetone, a tear gas. It had to be one of the most painful experiences I've ever
had.DavidJR - 13-3-2018 at 13:42
I thought you were going to say you blew yourself up with acetone peroxide...DavidJR - 16-3-2018 at 16:04
Uhh... turns out a solution of para-benzoquinone in dichloromethane can penetrate nitrile gloves...
DJF90 - 17-3-2018 at 01:38
Considering that nitrile gloves offer little to no protection to DCM ("splash protection" at best), I can't say I'm surprised.DavidJR - 17-3-2018 at 02:16
Yes, I realise this now.
I wasn't going about dipping my hands in it, it was just a splash & I did take the gloves off shortly after. So to be honest I wouldn't even say
they offer splash protection for DCM.LearnedAmateur - 17-3-2018 at 08:37
Damn, looks like my hands after a KMnO4 spillage, apparently p-benzoquinone can cause rashes and localised tissue necrosis - definitely keep an eye on
it. If it’s just stained though then it isn’t a huge deal but by the sounds of it, it’s not an overly pleasant compound to be working with..DavidJR - 17-3-2018 at 11:14
It's not painful at all so I'm hoping that it's just temporary staining. And yeah, it's not a particularly pleasant compound, the vapours are very
irritating to the eyes and throat, and even as a room temperature solid it sublimes readily so there's more vapour than you realise.RawWork - 12-4-2018 at 16:39
I accidentally poured glacial acetic acid on my hand. It made huge painful red stain on it. Same as burn. I remembered some advices that I have to
flush it with lots of water. I flushed it 20 minutes with running water. Believe it or not in 2 hours all color and pain dissapeared like nothing ever
happened. This happened many years ago.
I had a picture but removed it
[Edited on 13-4-2018 by RawWork]LearnedAmateur - 13-4-2018 at 01:29
Similar thing happened back when I was in school, accidentally got some acetic anhydride (synthesis of aspirin) on my finger and I had a stinging
white blister about a centimetre across immediately come up.
Oh yeah, and once I almost drank white spirit back when I was into making model aircraft, got a mouthful thinking it was a bottle of water (didn’t
check the bottle). That’s another reason to have a room dedicated to chemistry, and I’m really lucky it wasn’t anything else! Surprisingly it
didn’t really taste of much, it was mostly the smell that gave it away.stamasd - 16-6-2018 at 07:27
I was in high school (in another era, when you were actually allowed to do real chemistry in school) and was doing some reaction in a test tube with
benzene. Don't remember what it was, a nucleophilic substitution of some sort. I was actually my chemistry's teacher star pupil and was allowed to
work unsupervised. I was alone in the lab at the time. The reaction wouldn't start by itself so I started carefully heating the test tube over a
burner. Nothing happened. I started heating it more strongly. The benzene started vaporizing and condensing in the upper parts of the tube as a
condensation ring, then dripping back to the bottom (essentially refluxing in the tube). The reaction still wouldn't start. I heated it some more.
The condensation ring started getting higher, then higher, then reached the opening of the tube...
Suddenly I found myself holding a test tube (in a tube holder not in my hand, I'm not that crazy) with a column of flame about 1 meter high shooting
from it. And black soot started floating everywhere in the pristine lab. I had the good presence of spirit to take a big breath, then blow as hard as
I could parallel to the mouth of the tube. That extinguished the flame. I spent the next 30 minutes cleaning everywhere in the lab, and it was a big
room (about 10*20 meters).
I learned a valuable lesson that day, that I remember to this day. Fortunately without harm.
. (next step buy scales)
