Yesterday (or was it the day before, I forgot) due to my utter crap memory, I accidentally left the top off a bottle of fuming hydrochloric acid.
Only realized it some time later when the room started stinking.
And another one, a bit of a close shave actually:
I'd rigged up a hydrogen chloride gas (hydrochloric acid, in dry gaseous form) generator, and used it. It did not seem to be outputting much gas, so I thought hey, right, the chemicals inside must be spent, used up, done with, gasser finished. Hadn't used the aluminium foil&concentrated hydrochloric acid mixture for generating HCl gas before, but as it happened I currently have run out of concentrated sulfuric acid (I usually, for that purpose, fill a bottle with a cap modified to fit a length of rubber tubing, to direct the gas when it evolves. That way I don't have to clean my actual lab glassware, because it wasn't used, laziness pure and simple but it works just fine, quick and reliable and easy to control the rate of gas evolution, fill it with table salt, then add some strong sulfuric acid to the bottle contents, cap it, and then put the tube for the gas to exit from wherever I want the gas to be going)
So, gas generator with alternative mix 'spent', I took a nap, waiting for some solvents to cool down. Slept for a good few hours and then when I woke up, had a few slugs from my bottle of coke to wet my dry throat and mouth. Went for a cigarette in the kitchen, finished it, and began to don the gloves and goggles to go get back to work.
All of a sudden, the damn HCl generator bottle started to react fast and violent as hell, with an absolute torrent of hydrogen chloride fumes spewing out of the end of the hose, which was thrashing and lashing around like a whip being cracked, spraying corrosive, irritating, acidic gas, vapors, and the bottle was getting so damn hot that the HCl(aq) inside it was turning to a jet of steam, spraying boiling hot vaporised hydrochloric acid everywhere, whilst the bottle was becoming so hot it was very, very difficult and pretty painful to touch, the alarming thing was that it had started to swell, as though the overpressure was imminently going to make it suddenly rupture in a blast of boiling hot acid.
My old man, unfortunately had gone out fishing whilst I was asleep, and he'd locked the back door, I have a key but no WAY had I got time to go and grab it and come back, without risking the thing going off in my face. It was damned well close enough to that already. I grabbed the searing hot bottle full of boiling, bubbling acid, hose spraying acidic mist, HCl(g), and concentrated hydrochloric acid turned to steam EVERYWHERE, lashing about like a worm in a crow's beak (the hose, that is), and yet more acid, coming up in a searing hot jet out of the bottlecap too, overpressure building up fit to rupture the bottle any moment. Tried to ditch it outside, out the door. Couldn't, locked.
So I had to grab it, climb up onto the kitchen counter-top, shove the window open, toss this soon-to-be-boiling-acid grenade out of the window, and dive for cover, slamming the window closed on the way down.
Damned lucky I woke up just in time, the thing went from sedate and appearing inert to berserkirgang in about two or three seconds at most, right as I returned to the work being done. Damn good thing I DID go in there again to finish some workup duty.
All the same, even with the kitchen extractor fan on and windows closed (would have opened them to let air in for the fan but in this case, due to what was at that time, sitting just under the windowsill on the outside, spewing corrosive, searing hot fumes and spray, I wasn't about to do anything of the sort
) it was still nasty as hell in the kitchen, my workups had to do for later, when the hydrogen chloride fog had dissipated and the atmosphere once more safely breathable, absolutely stank, and my god, stung the eyes just to stand near the door separating the kitchen from the lounge.