Interesting chemicals
A thread for posting occasional chemistry factoids.
Chlorine trifluoride ClF3 Is generally too dangerous to consider using. It's a green liquid at room temperature, and a colorless gas when warmed (though warming it isn't really a good idea). It's an incredibly strong oxidizing agent - much more so than boring old oxygen. It self-ignites and burns most materials, most of them explosively. It also corrodes things generally considered non-corrodible: iridium, platinum, and gold. It burns most materials that oxygen can't: sand, asbestos, glass, tungsten, water, most fire retardants, concrete, the ashes of materials already burnt in oxygen, living flesh, ... It can be stored in vessels made from steel, copper, nickel or quartz - but the vessels must be scrupulously cleaned and passivated. The only reason the metal vessels can contain the chemical is because it reacts with the metals forming a thin layer of insoluble metal fluoride - but any contamination allows the chlorine trifluoride to burn through the passivation layer faster than it can re-form, and so the container is quickly turned into a non-container. The reaction with water is particularly violent and the products of the reaction include hydrogen chloride and hydrogen fluoride - in themselves fairly potent and alarming chemicals - and these are given off in the form of a steam or vapor due to the highly exothermic reaction. In a nasty chemical accident at Shreveport, Louisiana, nine hundred kilograms of ClF3 were being moved across a factory in a sealed metal cylinder, kept very cold to reduce the risk of reaction. Unfortunately the cold made the metal brittle, and it cracked spilling the ClF3 everywhere. It burned through the one-foot thick concrete floor, and a further three feet of gravel beneath. The remains of the man moving the cylinder were found about a hundred-and-fifty yards away, blasted there by the force of the explosion - official cause of death was a heart attack. Uses: It was tried in the 1940s as a rocket propellant, but kept setting fire to the rockets themselves, so was abandoned. The nazis tried to use it as a weapon, but it killed too many of their own chemists, and cost too much to produce. It is used (carefully, in small amounts) by the semiconductor industry to clean chemical vapor deposition chambers - it reacts with any slight contaminants on the walls of the chambers, burning them away: its high reactiveness is an advantage here as other lesser chemicals need to be activated by high temperature plasma to do the same work. It's used in the nuclear fuel processing industry during the production of uranium hexafluoride. |
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HF itself is an interesting chemical, hydrofluoric acid will eat through nearly anything, but it isn't nearly as volatile as ClF3. We used HF to do mineral assay for my boss' brother, who was a gold prospector in South Dakota. We dissolved ore samples with HF in a platinum dish ($900/ounce back in the late '70s), then diluted with water and ran them through the spectrometer to see what was in them. Yes, HF will even dissolve gold. I have no idea why platinum was immune to its effect. We stored it in a plastic bottle.
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Sulphur hexafluoride SF6, on the other hand, is completely safe (well ... as safe as water ... don't completely fill your lungs with it).
The opposite of breathing in helium. |
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And let us not forget dioxygen difluoride (FOOF):
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Aqua regia, which is a mixture of hydrochloric acid and nitric acid, will "dissolve" gold. The Nitric acid, HNO3, gives the gold an oxidising agent kick and then the chlorine atoms combine with the gold. I guess HF might do the same job as HCl providing you added some nitric acid to it? But I don't know and wouldn't like to try! HF is nasty stuff and other strong acids are like dishwasher liquid in comparison.
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Fluoride is actually the one halide that will not work.
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Approximate chemical formula for a human. The formula gets the ratios about right, but you have to multiply all the numbers by about seven hundred trillion to get the actual number of atoms in a typical person.
H375,000,000 O132,000,000 C85,700,000 N6,430,000 Ca1,500,000 P1,020,000 S206,000 Na183,000 K177,000 Cl127,000 Mg40,000 Si38,600 Fe2,680 Zn2,110 Cu76,114 Mn13 F13 Cr7 Se4 Mo3 Co1 source: the book ElEMeNTaL by Tim James (that's where I read about Chlorine trifluoride too) |
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Nitrogen trichloride NCl3 is a yellow oily liquid at room temperature.
It was first prepared by Pierre Louis Dulong in 1812 who, as a result, lost two or three fingers and an eye when it exploded twice. He must have been somewhat ashamed of his carelessness, as he chose to keep the results of his preparation secret. If Dulong had let his fellow chemists know how dangerous the stuff is, the famous scientist Humphry Davy might not have had a shard of broken glass embedded in his eye when his preparation of the same stuff also exploded, shattering the vessel that contained it. Davy's temporary blindness caused him to hire the young Michael Faraday as an assistant - who of course also went on to become a famous scientist. Faraday tried again with the preparation of nitrogen trichloride but that also exploded, injuring Davy again plus Faraday's hand resulting in him losing a fingernail. We now know that the compound, when pure, can be set off by heat, light, or the slightest shock. The same compound (though much diluted and therefore not explosive) is also responsible for that familiar "swimming pool" smell - it forms in the water when the disinfecting chlorine reacts with urea from bathers peeing or even just sweating in the water. |
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Graphene from rubbish.
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