The same goes for thallium \u2014 it is incredibly poisonous.<\/li>\n<\/ul>\n\nThis leaves us with sodium and potassium. But to be honest \u2014 the properties of all caustic alkalies are very similar.<\/p>\n
Sodium hydroxide \u2014 known as 'caustic soda' \u2014 is familiar to everyone. Potassium hydroxide as food additive E525 is also known. Both are similar in properties: they are highly hygroscopic, meaning they attract water and 'melt' in the air. They dissolve well in water, releasing a significant amount of heat.<\/p>\n
'Melting' in the air essentially means the formation of very concentrated solutions of alkalies. Therefore, if you place a piece of caustic alkali on paper, skin, or some metals (like aluminum) \u2014 after some time, you'll find that the material has been significantly damaged! What was shown in 'Fight Club' is quite close to the truth: indeed, sweaty hands in caustic will hurt! Personally, I found it more painful than hydrochloric acid (discussed below).<\/p>\n
However, if your hands are very dry \u2014 you probably won't feel anything in dry alkali.<\/p>\n
Caustic alkalis effectively break down fats into glycerin and fatty acid salts \u2014 that's how soap is made (hello, 'Fight Club!'). Proteins are also decomposed, albeit a bit slower \u2014 in principle, alkalis dissolve flesh, especially strong solutions \u2014 yes, when heated. A downside compared to hydrochloric acid (also discussed below) is that all alkalis absorb carbon dioxide from the atmosphere, thus their strength will gradually decrease. Additionally, alkalis react with components of glass \u2014 glass becomes cloudy, although it requires effort to completely dissolve it. <\/p>\n
Tetraalkylammonium hydroxides are sometimes classified as caustic alkalis, for example.<\/p>\n
Tetramethylammonium hydroxide.<\/b>Sulfuric Acid<\/h3>\n
\nH2SO4<\/b>
By the way, while taking water, sulfuric acid heats up quite a bit, making the situation even more intense. Therefore, washing it away with water is a very bad idea. It's better to use oil (to wash it off, not to rub it in \u2014 and then wash it away with water). Or use a large stream of water to cool it down immediately.<\/p>\n
\"First water, then acid \u2014 otherwise, disaster will strike!\" \u2014 this is precisely about sulfuric acid, even though for some reason everyone thinks it applies to any acid.<\/p>\n
As an oxidizer, sulfuric acid oxidizes the metal surfaces to oxides. And since the interaction of oxides with acids occurs with water as a catalyst \u2014 and sulfuric acid doesn't give up water \u2014 the effect known as passivation occurs: a dense, insoluble, and impermeable oxide film protects the metal from further dissolution.<\/p>\n
It is through this mechanism that concentrated sulfuric acid is sent far away with iron and aluminum. Interestingly, if the acid is diluted, water appears, and it can't be sent \u2014 the metals dissolve.<\/p>\n
By the way, sulfur trioxide SO3 dissolves in sulfuric acid to produce oleum \u2014 which is sometimes mistakenly written as H2S2O7, but that's not entirely correct. Oleum has an even greater affinity for water.<\/p>\n
Personal experience of sulfuric acid on the skin: a bit warm, then slightly burning \u2014 washed off under the tap, nothing serious. Don't trust the movies, but I wouldn't recommend letting it drip on your face.<\/p>\n
Organic chemists often use chrome alum or the \"chrome mixture\" \u2014 this is potassium bichromate dissolved in sulfuric acid. Essentially, this is a solution of chromic acid, good for washing dishes from organic residue. It burns when it comes into contact with skin, but essentially it's sulfuric acid plus toxic hexavalent chromium. You won't get holes in your skin, maybe just on your clothes.<\/p>\n
The author of these lines knows an idiot who used potassium permanganate instead of potassium bichromate. It slightly exploded when it contacted organic material. The people present were just lightly frightened.<\/p>\n
Hydrochloric acid<\/h3>\n \nHCl<\/b>
When this comes into contact with skin, it burns a bit more intensely, subjectively \u2014 it also itches, and besides, it smells: if you work a lot with concentrated hydrochloric acid in a lab with poor ventilation \u2014 your dentist will thank you: you'll be enriching him with fillings. By the way, chewing gum helps. But not much. It's better to have good ventilation.<\/p>\n
Since it is not oily and doesn't heat up much with water, its corrosiveness is only to metals, and not to all. By the way, steel is passivated in concentrated hydrochloric acid and tells it, \"no way!\" This is used during transportation.<\/p>\n
Nitric acid<\/h3>\n \nHNO3<\/b>
As an oxidizer, it passivates many metals, which become covered with an insoluble film and say: \"goodbye\" \u2014 this includes chromium, iron, aluminum, cobalt, nickel, and others. <\/p>\n
The skin reacts instantly according to the xantho-protein reaction \u2014 there will be a yellow spot, which means that you, %username%, are indeed made of protein! After a while, the yellow skin will peel off, similar to a burn. It stings less than hydrochloric acid, although it smells just as bad \u2014 and this time it's more toxic: airborne nitrogen oxides are not good for the body.<\/p>\n
In chemistry, there is a so-called 'nitrating mixture' \u2014 the most popular one consists of sulfuric and nitric acid. It is used in syntheses, particularly in the production of a fun substance \u2014 nitrocellulose. In terms of causticity, it's the same as chromic acid plus a pretty yellow skin.<\/p>\n
There is also 'aqua regia' \u2014 this is one part of nitric acid to three parts of hydrochloric acid. It is used for dissolving certain metals, mainly precious ones. The drop method for testing samples of gold items is based on different ratios and adding water \u2014 by the way, it's very hard to trick specialists in this method with a counterfeit. In terms of skin causticity \u2014 it\u2019s the same as the 'nitrating mixture' plus it smells terrible, an unmistakable odor that is also quite toxic.<\/p>\n
There is also 'reverse aqua regia' \u2014 when the ratio is reversed, but this is rare.<\/p>\n
Phosphoric acid<\/h3>\n \nH3PO4<\/b>
Concentrated orthophosphoric acid (85%) is a sort of syrup. The acid itself is moderately strong, and it is often used in the food industry \u2014 by the way, when you get dental fillings, the surface of the tooth is pre-etched with phosphoric acid.<\/p>\n
Its corrosiveness is average, but there\u2019s an unpleasant nuance: this syrup absorbs well. So if it drips on things \u2014 it will soak in, and then it will gradually start to eat away at them. If a stain or hole occurs from nitric and hydrochloric acids \u2014 the phosphoric one will cause the item to disintegrate, especially noticeable on shoes, when the hole starts to crumble until it becomes a complete perforation.<\/p>\n
Well, overall it's hard to call it caustic.<\/p>\n
HF<\/h3>\n \nHydrofluoric acid<\/b>
A weak acid that fiercely loves fluoride ions, forming stable complexes with everything it can. Therefore, surprisingly, it dissolves things that other, stronger companions cannot, and is often used in various mixtures for dissolving. When it comes in contact with your hand, the sensations will mostly originate from other components of such mixtures, but there is a caveat.<\/p>\n
Hydrofluoric acid dissolves SiO2. That is, sand. That is, glass. That is, quartz. And so on. No, if you splash this acid on a window, it won't dissolve, but a cloudy stain will remain. To dissolve it, you need to hold it for a long time, and preferably \u2014 heat it. Dissolving releases SiF4, which is so beneficial for health that it's better to do this under a fume hood.<\/p>\n
A small but pleasant nuance: silicon is found in your nails, %username%. So if hydrofluoric acid gets under your nails \u2014 you won't notice anything. But you won't be able to sleep at night \u2014 it will hurt SO much that sometimes you'll wish to tear off your finger. Believe me, my friend \u2014 I know.<\/p>\n
And in general, hydrofluoric acid is toxic, carcinogenic, absorbed through the skin, and a lot more \u2014 but today we're talking about causticity, right?<\/p>\n
Remember, we agreed at the very beginning that there won't be any fluorine? There won't be any. But there will be...<\/p>\n
Fluorides of inert gases<\/h3>\n \nIn fact, fluorine is a tough character, and you can't mess around with it, which is why some inert gases form fluorides with it. Known stable fluorides include: KrF2, XeF2, XeF4, XeF6. All of these are crystals that decompose in the air at varying speeds and willingly with moisture into hydrofluoric acid. The causticity is corresponding. <\/p>\n
Hydriodic acid<\/h3>\n \nHI<\/b>Chloric acid<\/h3>\n
\nHClO4<\/b>
When it comes into contact with skin, it burns like hydrochloric acid. It has a strong odor. When you see in movies that someone throws a body into a container of hydrochloric acid and it dissolves, yes, that's possible \u2014 but it takes time or requires heating. If heated, it can explode (as mentioned above). So be critical of cinema (I think I saw this in '10 Cloverfield Lane').<\/p>\n
By the way, the causticity of chlorine oxides (VII) Cl2O7 and chlorine oxide (VI) Cl2O6 results from the fact that these oxides form hydrochloric acid when interacting with water.<\/p>\n
Now let's imagine that we've decided to combine strong acidity with the causticity of fluorine in a single compound: we take a hydrochloric or sulfuric acid molecule and replace all the hydroxyl groups with fluorine! The resulting substance would be quite nasty: it would react with water and similar compounds \u2014 and a strong acid and hydrofluoric acid would be generated at the site of the reaction. What do you think?<\/p>\n
Fluorides of sulfur, bromine, and iodine<\/h3>\n \nRemember we agreed to consider only liquids? For this reason, chlorine trifluoride ClF3<\/b>, which boils at +12 \u00b0C, although all the horror stories about it being horrendously toxic, igniting glass, requiring a gas mask, and that when spilling 900 kilograms \u2014 it can eat through 30 cm of concrete and a meter of gravel \u2014 are all true. But we agreed \u2014 only liquids.<\/p>\n
However, there is a yellow liquid \u2014 iodine pentafluoride IF5<\/b>, a colorless liquid \u2014 bromine trifluoride BrF3<\/b>, pale yellow \u2014 bromine pentafluoride BrF5<\/b>, which are just as effective. BrF5, for example, also dissolves glass, metals, and concrete.<\/p>\n
Similarly, among all sulfur fluorides, only the liquid is disulfur decafluoride (sometimes referred to as pentafluorosulfur) \u2014 a colorless liquid with the formula S2F10<\/b>. However, this compound is quite stable at normal temperatures, does not decompose in water \u2014 making it not particularly corrosive. It is, however, four times more toxic than phosgene with a similar mechanism of action.<\/p>\n
By the way, it is said that iodine pentafluoride was the 'special gas' used to fill the atmosphere in the rescue shuttle in the final scenes of the movie 'Alien' from 1979. I honestly don't remember.<\/p>\n
Superacids<\/h3>\n \nThe term 'superacid' was introduced by James Conant in 1927 to classify acids that are stronger than ordinary mineral acids. Some sources classify hydrochloric acid as a superacid, but it is not \u2014 it is an ordinary mineral acid.<\/p>\n
A series of superacids consists of minerals that have halogen attached: the halogen pulls electrons towards itself, causing all atoms to become very agitated, and as usual, hydrogen gets away in the form of H+ \u2014 kaboom: thus, the acid becomes stronger.<\/p>\n
Examples \u2014 hydrofluoric and hydrochloric acids<\/b>
Then some clever person thought: why not take a Lewis acid (a substance capable of accepting a pair of electrons from another substance) and mix it with a Br\u00f8nsted acid (a substance capable of donating a proton)! They mixed antimony pentafluoride with hydrofluoric acid \u2014 resulting in hexafluoroantimonic acid HSbF6<\/b>. In this system, hydrofluoric acid releases a proton (H+), while the conjugate base (F\u2212) is isolated by a coordinate bond with antimony pentafluoride. This forms a large octahedral anion (SbF6\u2212), which is a very weak nucleophile and a very weak base. Once 'liberated', the proton induces the superacidity of the system \u2014 with a Hammett function of -28!<\/p>\n
Then others came along and said, why take the weak Br\u00f8nsted acid \u2014 and came up with something else.<\/p>\n
Tetrafluoromethanesulfonic acid<\/b>
Then a group of scientists from the chemistry department at a Californian university, led by Professor Christopher Ried, collaborated with colleagues from the Institute of Catalysis at the Siberian Branch of the Russian Academy of Sciences (Novosibirsk) and invented carboranoic acid H(CHB11Cl11). Well, it was named 'carboranoic' for the average person, but if you want to feel like a scientist \u2014 say '2,3,4,5,6,7,8,9,10,11,12-undecachloro-1-carba-closo-dodecaborane(12)' three times fast.<\/p>\n
This is what the beauty looks like.<\/b>
Later, Christopher Ried said in an interview with Nature's news service: 'The idea of synthesizing carboranoic acid came from fantasies \u201cabout molecules never before created.\u201d Together with his colleagues, he wants to use carboranoic acid to oxidize the inert gas xenon atoms \u2014 simply because no one has ever done this before. Original, to say the least.'<\/p>\n
Well, since superacids are just ordinary acids, they act like ordinary acids, just a bit stronger. It\u2019s clear that they will burn the skin, but that doesn\u2019t mean they will dissolve everything. Fluorosulfonic acid is a special case, but that\u2019s all thanks to fluorine, just like in hydrofluoric acid.<\/p>\n
Trihaloacetic acids<\/h3>\n \nSpecifically \u2014 trifluoroacetic and trichloroacetic acids<\/b>
The cutest is trifluoroacetic acid: a 20% solution destroys metals, cork, rubber, Bakelite, polyethylene. It burns on the skin and forms dry ulcers that reach down to the muscle layer. <\/p>\n
Trichloroacetic acid is like the little brother in this regard, but it also has some strength. By the way, applause for the fairer sex: in pursuit of beauty, some opt for the so-called TCA peeling procedure (TCA stands for TetraChloroAcetate) \u2014 when this very trichloroacetic acid is used to dissolve the upper rough layer of the skin.<\/p>\n
However, if the cosmetologist gets distracted on the phone, a fail might happen.<\/b>habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"\u2013\u00a0\u042d\u0442\u0438 \u0438\u0434\u0438\u043e\u0442\u044b \u043f\u043e\u043c\u0435\u0441\u0442\u0438\u043b\u0438 \u0444\u0430\u0440\u0444\u043e\u0440\u043e\u0432\u044b\u0439 \u043a\u043e\u043d\u0442\u0435\u0439\u043d\u0435\u0440 \u0441\u043e \u00ab\u0441\u0442\u0443\u0434\u043d\u0435\u043c\u00bb \u0432 \u0441\u043f\u0435\u0446\u0438\u0430\u043b\u044c\u043d\u0443\u044e \u043a\u0430\u043c\u0435\u0440\u0443, \u043f\u0440\u0435\u0434\u0435\u043b\u044c\u043d\u043e \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u0443\u044e\u2026 \u0422\u043e \u0435\u0441\u0442\u044c \u044d\u0442\u043e \u043e\u043d\u0438 \u0434\u0443\u043c\u0430\u043b\u0438, \u0447\u0442\u043e \u043a\u0430\u043c\u0435\u0440\u0430 \u043f\u0440\u0435\u0434\u0435\u043b\u044c\u043d\u043e \u0438\u0437\u043e\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0430, \u043d\u043e \u043a\u043e\u0433\u0434\u0430 \u043e\u043d\u0438 \u043e\u0442\u043a\u0440\u044b\u043b\u0438 \u043a\u043e\u043d\u0442\u0435\u0439\u043d\u0435\u0440 \u043c\u0430\u043d\u0438\u043f\u0443\u043b\u044f\u0442\u043e\u0440\u0430\u043c\u0438, \u00ab\u0441\u0442\u0443\u0434\u0435\u043d\u044c\u00bb \u043f\u043e\u0448\u0435\u043b \u0447\u0435\u0440\u0435\u0437 \u043c\u0435\u0442\u0430\u043b\u043b \u0438 \u043f\u043b\u0430\u0441\u0442\u0438\u043a, \u043a\u0430\u043a \u0432\u043e\u0434\u0430 \u0447\u0435\u0440\u0435\u0437 \u043f\u0440\u043e\u043c\u043e\u043a\u0430\u0448\u043a\u0443, \u0432\u044b\u0440\u0432\u0430\u043b\u0441\u044f \u043d\u0430\u0440\u0443\u0436\u0443, \u0438 \u0432\u0441\u0435, \u0441 \u0447\u0435\u043c \u043e\u043d \u0441\u043e\u043f\u0440\u0438\u043a\u0430\u0441\u0430\u043b\u0441\u044f, \u043f\u0440\u0435\u0432\u0440\u0430\u0449\u0430\u043b\u043e\u0441\u044c \u043e\u043f\u044f\u0442\u044c \u0436\u0435 \u0432 \u00ab\u0441\u0442\u0443\u0434\u0435\u043d\u044c\u00bb. \u041f\u043e\u0433\u0438\u0431\u043b\u043e \u0442\u0440\u0438\u0434\u0446\u0430\u0442\u044c \u043f\u044f\u0442\u044c \u0447\u0435\u043b\u043e\u0432\u0435\u043a, \u0431\u043e\u043b\u044c\u0448\u0435 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":24989,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-33254","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t
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