Not that any of you guys care, but I am now realizing why I got out of chemistry in my first year of college. I found it all too finicky. Some adult part of my brain was protecting me I can now see. I am constitutionally incapable of being careful. Art is made for people like me. (I even avoided ceramics because of the requirement to do chemistry and understand redox reactions.)
Thanks for handling this part of life, all you clear thinkers.
Do not try what you are about to see at home. Ever!
Nitrogetthehelloutofhere?
My dad tells a story of someone in his undergraduate chemistry class making trinitrotoluene, or some related compound. I canât remember the details but they ended up having to evacuate the lab.
My classmate lost his basement lab to a fire resulting from a nitroglycerin synthesis going wrong. (The explosion lit some dust on the table, remainder of something made earlier, and the rest escalated from that.) I later got some interesting-smelling organic chemistry books from him.
Avoid nitroglycerin, unless you are really experienced (and I mean really, not just thinking you are).
On another thought, it is one of potential tests for safety design of microreactorsâŚ
Random thought⌠what about fusion of chemistry and robotics? A remotely operated lab for riskier work, with 3d-printed manipulators, possibly hydraulic- or pneumatic-actuated for operation in flammable/explosive atmospheres? Could save a number of fingersâŚ
âŚfurther thought - and could be built into an old safe, with thick steel walls, calculated to withstand worst-case event. No need even for viewports, in the age of cheap little cameras. Whatever hell is unleashed, it can stay confined. With suitable air exclusion, would also work for operation on extremely sensitive or dangerous/toxic materials (toxic, biohazardâŚ) while protecting the operators. Could be even made as disposable, with built-in self-destruct means (incineration-friendly, for example, or ready for encasing in concrete and throwing into the ocean depth) if something goes wrong (or right).
Had some nice ones but vaporized in the plasma flash
Whereâs Waldo?
Exactly like that, in principle. The idea is rather old, the innovation would be having the manipulators based on opensource hardware, using off-the-shelf or downloadable/printable robotic arms (and bringing the cost down to the range of affordability for garage labs).
Why not use something like Oculus Rift + ControlVR or a similar device that measures body, hand position and finger position.
Thatâs how robots should really be piloted. All that dicking around with joysticks and WADS and mouse looking. I canât believe we havenât done something like that with a lunar rover yet, or volcano bots or something. The delay shouldnât be that bad from here to the moon. 2.56 seconds round trip if my calculations are correct.
I fully agree! With little caveats.
For prolonged operating of real machines, Iâd prefer some sort of an exoskeleton, or controls, for at least rudimentary force feedback and, more important, to rest hands on to avoid fatigue (see the âgorilla armâ problem of touchscreen systems).
Thought re roundtrip-delayed (or slow-moving) systems: have a wireframe model of the arms overlaid over the real ones, so you see both the destination position and the real position. Feeling your body moving in âreal worldâ but seeing it moving only delayed could screw up with proprioception and require too much of conscious processing.
Thereâs more than one way to destroy a basement⌠My friend was teaching a physics for poets class and was looking for fun demonstrations, so he decided to use liquid nitrogen in a sealed 2 liter soda pop bottle. His first trial was in his basement office where he blew all the windows out.
Sounds like a bit too much of LN2. 
These bottles can withstand about 10 atm (150 psig, or 1 MPa of overpressure). Counting as ideal gas, that equals 0.9 moles of N2, which is 25 grams, which (with 0.809g/cm3 density) is about 31 mL. Which is about a shot glass, give or take, depending where you are.
You will need quite a bit more to burst such bottle, but not THAT much more; maybe twice the amount to be on the safe side, maybe not even that. Much more than whatâs needed and youâre in a cryogenic BLEVE situation, albeit without the accompanying fire.
And you can asphyxiate yourself if you arenât careful. Human oxygen requirements are at least 10% of oxygen, at nominal air pressure (100kPa), which is about half of the normal concentration. One cubic meter of N2 is needed for two cubic meters of space to get it there. One cubic meter of N2 is about 44.6 moles, about 1250 grams. Converted to LN2 it is about 1.55 liters. For a 16 m3 basement, 8 m3 of N2 are needed. A somewhat large 12.3 liter Dewar flask would be needed here, assuming homogenous mixing. (Youâre likely to get a layer of cold nitrogen on the floor, though, as the gas as-evaporated will be denser, so count with stratification. This will bring the amount of N2 needed to cause trouble quite a bit down.) A coffee-grade thermos bottle of LN2 is not much of a risk, for sanely big basements.
(Then thereâs a risk of oxygen dissolving, which will tend to enrich the LN2 with LOX and also enrich the situation with LOX-related risks. Which are rich and diverse and can announce themselves with a loud acoustic effect; many things soaked with LOX turn into pretty decent explosives. There was a case when pork rinds were frozen with LN2 before grinding, but oxygen condensed on them, and the resulting explosion turned the grinder into shrapnels and killed one person.)
My uncle got a glass bottle with dry ice exploding in his hand, when he was a kid. Survived fairly unscathed and much wiser.
(Pro tip: donât do that. Unless you really well know what do you want to achieve and have a shrapnel shield. For noise, plastic bottles are way safer, though you should take care of the bottlecap end, this can turn into a rather powerful missile. A safe envelope. e.g. a trashcan, will help here. Putting the bottle upside down there will minimize risk of the cap taking off, or at least will dissipate some of its energy by ricocheting from the walls.)
Also, a toxicology note. According to here, exposure of 2.5% of total body area to 70% HF can lead to death. Average body area for human males is 1.9 m2, for females 1.6 m2, which translates to fairly large 479 cm2 or 400 cm2 (in the latter case, a 20x20 cm area). Which is fairly big. (Or fairly small, in the splash/spill scenario where entire bottles or more are involved.)
Most of the dermal-route fatalities involve fairly large spills or splashes.
My guess here is that low few milliliters used for smaller-scale glass etching do not present a grave hazard, a drop on skin or accidental touch wonât be pleasant but also wonât be fatal, especially if quickly treated. The fairly large vessel used in the experiment in the video is however quite respect-inducing.
Always good to run the numbers, at least for ballpark figures. A mythical danger can then get a more concrete shape and becomes less scary.
âŚand always good to keep brain in shape by doing such calculationsâŚ
âŚand even better doing it in public, as not only you share potentially useful or at least interesting data, but if you make a mistake it can be found and corrected. I encourage you to check my calculations, both to get some practice and to cover my back as I can always screw up.
Yes, that was the most feared substance in the lab where I was doing my PhD. A student working with mercury-contaminated soil found out that it can kill you a year after you drop a few drops onto your glove, and seriously considered giving up on the project.
Wow. I mean, Iâve had some really good coke in my time, but Iâve never, ever been that high.
Iâm actually just a chemist on wikipedia (a reader not an editor). I am fortunate to have survived the teenage pyromaniac phase uninjured. I switched to playing with computers just before getting the BS in chemistry.
But in an industrial safety class I took at TI several decades ago, they told us that just a drop or two of HF, if it gets through a pinhole in your glove, can really hurt. They explained that it is a bone-seeker, and youâll experience pain in that finger after a small exposure through the glove. You wonât notice the pinhole immediately. And then you will. And it takes a while (weeks and months, not minutes and seconds) to get better.
As with a lot of things, it isnât so much the LD50 as it is a question of how it will affect your life later on.
Oh, and I asked before, but Iâll ask again ⌠in a HazMat cleanup, what is the normal reactant for HF? Just wondering ⌠I assume calcium-something, so as to make fluorite. Very stable stuff, fluorite. But calcium-what? Carbonate? Sulfate? Oxide? Gluconate was mentioned for medical treatment, but Iâm assuming environmental cleanups would use something else⌠If nitric was in the mess as well, you probably wouldnât want to use gluconate.
Thatâs without doubts. Good gloves are a must. (Or no gloves (you notice contamination way faster) and a LOT of attention, but that is what I woud do only when working only with drops.)
Thought: preventive application of the calcium gluconate gel before donning the gloves. Or any calcium-bearing compound that wonât irritate the skin.
Year or two is nothing in the Great Scheme of Things. It will pass.
Still, better be prepared.
Yes. But you will live. And you will recover over time, at least mostly (unless unlucky). So it induces respect, but should not induce fear.
Here is some description of a spill response.
http://www.concordia.ca/content/dam/concordia/services/safety/docs/EHS-DOC-008_HF%20guidelines.pdf
They apparently use sodium carbonate as a neutralization agent. Apparently the soluble fluoride is not being considered a big problem. (Usage of a calcium based material would apparently have problems; e.g. formation of insoluble layer on the powder used for neutralization, and if we use e.g. calcium chloride solution, weâd end with insoluble calcium fluoride, but also hydrochloric acid.) The sodium carbonate is probably the easiest, cheapest, most available way.
They also use polypropylene sorbent pads.
High-concentration spills are suggested to be diluted first, but slowly as the dilution produces heat that may boil off some gaseous HF.
Iâve only worked with biological nasties, but double-glove protocol is common with them. Use contrasting colours, so you notice if the first has been damaged. No gloves would be a suicide note. 
Yes! Thatâs a must-do for nastier things. (And there are WAY nastier things than HF, regardless how bad rap it has.) Also, an important thing for routine work; familiarity brings contempt and your guards go down and even low-probability events can become fairly probable when they happen often enough.
Edit: Was aware of the double-glove protocol. Didnât know about the contrasting colors, makes good sense.
Edit: Also, sometimes the protective equipment can make things worse. A glove can increase risk of getting snagged in rotating equipment, or get things spilled into it. A lead shield can in some situations generate annoying bremsstrahlung. Itâs always good to balance the pros and cons.
