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Crystallization is a very good way to purify substances (as a chemist, I take advantage of this quite frequently!) With the exception of compounds that co-crystallize (in which case the crystal will have a very well-defined ratio of the components), almost all crystals are nearly pure substances. The crystal structure has little room for deviation from perfect repetition of its unit cell.Essentially, you can think of it like so: as the crystal is growing, dissolved (or molten) molecules or ions bump into the side of the crystal. If they happen to fit just right, they will stick and be incorporated into the crystal, and if not, they will just bounce off and go back into solution (or melt). Even water molecules will most bounce off of the growing ice crystal--they have to hit at just the right angle and just the right position with just the right speed to stick, but non-water molecules or ions have no chance of being incorporated in the crystal. If the crystal forms too quickly, it can have defects, and potentially contain impurities, but if it is still crystalline, then it must be quite close to pure and perfect.A corollary to this is that mixtures of substances are much harder to crystallize. This is essentially the reason behind why salt melts ice (salt+water is harder to freeze than pure water, and therefore salt+ice is easier to melt than pure ice). Ice will also melt very quickly if exposed to absolute alcohol (and will get very cold!) and vodka won't freeze until it gets below –25°C.Hope this helps!
Years ago the hydrous potassium permanganate was sold as an oral treatment for radiation poisoning in local drug stores. The crystals are a pale lavender color, while the pure potassium permanganate is a deep dark almost black substance.
Quote from: William McC on 05/09/2016 02:48:38Years ago the hydrous potassium permanganate was sold as an oral treatment for radiation poisoning in local drug stores. The crystals are a pale lavender color, while the pure potassium permanganate is a deep dark almost black substance. Potassium permanganate does not form a a stable hydrate.No plausible hydrate would be a "pale lavender" since even a 1 % solution of the stuff is nearly black.Potassium iodide is (occasionally) used in reducing the damage caused by exposure to radioisotopes of iodine (such as happened at TMI, Chernobyl or Fukushima).In that case it's the iodide bit that's doing the work.Lord knows what you were being sold.One vague possibility is potassium perchlorate which will (IIRC) co-crystallise with permanganate. You might be able to get a lavender crystal that way.It's far from clear why anyone would bother, though the fact that it wouldn't work wouldn't top people selling it.
It was pharmaceutical quality. It was lavender, some might say violet, and it was potassium permanganate hydrate. I used it to start fires with it. The very small container had "oral dose" written on the container. Everyone in my area used to know what it was and what it was for. I believe you were supposed to dissolve it before taking it. It was for severe radiation poisoning. I was also told that you cannot just dissolve potassium permanganate anhydrous in water and take it internally no matter the dose. I was told you have to use the hydrate crystals. I also used to purchase the super pure anhydrous granular form of potassium permanganate from Mallincrodt , which was such a deep dark purple that it appeared almost black. It was a powerful oxidizer. Although the violet or lavender crystals would react with glycerin, it was nothing like the way glycerin reacted with the anhydrous potassium permanganate. Just sharing what I know, you do not have to concur. Sincerely, William McCormick
Are you sure that you are not getting confused and were using iodine? There would be no benefit whatsoever of taking potassium to alleviate radiation exposure. In fact, that is likely to exacerbate the symptoms of radiation exposure, because your body is full of potassium (in your cells), and part of the sickness of acute radiation toxicity is the rupture of millions of cells and the spillover into the blood of a large burden of formerly intracellular potassium.Iodine is the only sensible remedy against certain forms of radiation exposure, specifically radiation that involves radioactive iodine species. The rationale is that exogenous iodine will compete with the radioactive form to prevent or minimise uptake by the thyroid gland, where incorporation of radioactive iodine would injure the gland and possibly lead to cancer.The only explosive I have think of that would involve iodine is nitrogen triiodide, which you make with ammonia and sodium hydroxide. It detonates on mild contact.
Quote from: William McC on 05/09/2016 23:36:36It was pharmaceutical quality. It was lavender, some might say violet, and it was potassium permanganate hydrate. I used it to start fires with it. The very small container had "oral dose" written on the container. Everyone in my area used to know what it was and what it was for. I believe you were supposed to dissolve it before taking it. It was for severe radiation poisoning. I was also told that you cannot just dissolve potassium permanganate anhydrous in water and take it internally no matter the dose. I was told you have to use the hydrate crystals. I also used to purchase the super pure anhydrous granular form of potassium permanganate from Mallincrodt , which was such a deep dark purple that it appeared almost black. It was a powerful oxidizer. Although the violet or lavender crystals would react with glycerin, it was nothing like the way glycerin reacted with the anhydrous potassium permanganate. Just sharing what I know, you do not have to concur. Sincerely, William McCormickWell, thanks for that.This bit "I was also told that you cannot just dissolve potassium permanganate anhydrous in water and take it internally no matter the dose. I was told you have to use the hydrate crystals. "shows that it can't have been potassium permanganate.Because you get the same solution if you dissolve the anhydrous form of a salt as you get if you dissolve the hydrate.As I said, even 1% KMnO4 in water is nearly black.How could you have a crystal that is solid yet that pale?It's impossible.Which is more plausible?That the stuff you talk of exists, but doesn't get a mention anywhere on the web, doesn't make sense given the colour and breaks the laws of chemistry by not forming the same solution as the anhydrous form and there's no way it would help against radiation poisoning or you were misled / don't remember properly?It's not me who doesn't concur with your assertion. It's reality that's doing that.
Most or all chemicals when in solution are no longer the substance they were. It can be very difficult to get them back to their original formula. Sodium hydroxide the alkaline is actually Na2O,
Quote from: William McC on 08/09/2016 04:29:34Most or all chemicals when in solution are no longer the substance they were. It can be very difficult to get them back to their original formula. Sodium hydroxide the alkaline is actually Na2O, Since that's plainly wrong I stopped reading at that point.Sodium hydroxide- the alkali- is NaOH. (Also please note the difference between the adjective alkaline and the noun alkali)Na2O does exist- it's sodium oxide. And so it isn't a hydroxide.It will react with water to give the hydroxide which is a totally different chemical.
William,I think you might be confusing anhydrous and anhydride. "Dehydration," or removal of water, can lead to either. The difference is that no covalent bonds need to be broken to form an anhydrous form (it is a mixture of whole water molecules, and another species that is unchanged by the dehydration), while an anhydride is produced by the cleavage of covalent bonds, releasing water (which hadn't existed in tact before the dehydration), and an entirely new molecule (or substance) that is the anhydride.Copper sulfate can form beautiful blue crystals of the pentahydrate: CuSO4•5H2O (made up of an ionic lattice containing a Cu2+ ion, an SO42– ion, and 5 molecules of H2O). On strong heating, the water molecules evaporate out, leaving anhydrous copper sulfate: CuSO4CuSO4•5H2O --> CuSO4 + 5H2OIn contrast, acetic acid (H3CCOOH) can be dehydrated under very forcing conditions to make water (H2O) and acetic anhydride (H3CCOOOCCH3):2 H3CCOOH --> H2O + H3CCOOOCCH3In the same sense, sodium oxide is the anhydride of sodium hydroxide:2 NaOH --> H2O + Na2Osee the attached diagram.
Quote from: chiralSPO on 09/09/2016 04:46:44William,I think you might be confusing anhydrous and anhydride. "Dehydration," or removal of water, can lead to either. The difference is that no covalent bonds need to be broken to form an anhydrous form (it is a mixture of whole water molecules, and another species that is unchanged by the dehydration), while an anhydride is produced by the cleavage of covalent bonds, releasing water (which hadn't existed in tact before the dehydration), and an entirely new molecule (or substance) that is the anhydride.Copper sulfate can form beautiful blue crystals of the pentahydrate: CuSO4•5H2O (made up of an ionic lattice containing a Cu2+ ion, an SO42– ion, and 5 molecules of H2O). On strong heating, the water molecules evaporate out, leaving anhydrous copper sulfate: CuSO4CuSO4•5H2O --> CuSO4 + 5H2OIn contrast, acetic acid (H3CCOOH) can be dehydrated under very forcing conditions to make water (H2O) and acetic anhydride (H3CCOOOCCH3):2 H3CCOOH --> H2O + H3CCOOOCCH3In the same sense, sodium oxide is the anhydride of sodium hydroxide:2 NaOH --> H2O + Na2Osee the attached diagram.As you add water to most of the chemicals above, you get different compounds at different ratios of water to original chemical. That should highlight that the perfect formula is just an indicator of one or some of the reactions taking place. By stating a certain reaction you are claiming some exact ratio, which you do not state. You state some perfect mathematical solution. Solid sodium hydroxide has free water present in it. The reason is it is partially crystalizing in that state. Even though it is very hungry for water, and the addition of a lot more water creates the products we use in industry clear lye.
All of these chemicals and reactions create different chemicals different compounds at different levels of hydration. In industry and in life so many times people think the pure product is more potent while in pure form. However it is the action and reactions created with the addition of water that cause the effect it was designed to cause. So by using enough water, a weakened watered down solution, the product actually works faster and more powerfully. Lye is like that. When you put a very watered down solution of lye on oxidized aluminum, the reaction and heat liberated is really amazing. It totally cleans and brightens the aluminum. However you need the excess water to create the reaction. These reactions are always misstated by chemistry. And because the reactions are too complex to actually and totally understand, by placing a formula or reaction upon them, they rule out the factory accidents that occur by the actual complex reactions that are actually taking place.
I do not agree with your explanation. I believe you are stating a memorized understanding. Having worked with the EPA I saw that their college trained chemists did not understand chemistry. Because many plating companies had 8th grade chemists that could literally take what the EPA thought was dangerous hazardous waste, and turn it back into water that they would drink, and pure chemicals that they reused again. These plating companies had to pay for carting empty drums of waste that the EPA chemists thought was a byproduct of a certain reaction, even though the plating chemists could reclaim that material as they used it. These 8th grade chemists could plate up or down. By using a substance with a siamese bond and usually an oxide or chloride atom, they could plate that material up to or down to the element just above or just below. It was more of an art rather than a simple mathematical formula. However they did it everyday. If you look at plating tanks in the dark you will see they create light from the reaction taking place. It was explained to me that there was an atomic level reaction taking place. This was so true that some poor plating shops were creating radio active substances in their plating tanks from ordinary chemicals that are not radio active. So in some cases the EPA was right, and in all cases the 8th grade chemists that knew all of the above were correct
. This was so true that some poor plating shops were creating radio active substances in their plating tanks from ordinary chemicals that are not radio active.
Quote from: William McC on 10/09/2016 14:14:19Quote from: chiralSPO on 09/09/2016 04:46:44William,I think you might be confusing anhydrous and anhydride. "Dehydration," or removal of water, can lead to either. The difference is that no covalent bonds need to be broken to form an anhydrous form (it is a mixture of whole water molecules, and another species that is unchanged by the dehydration), while an anhydride is produced by the cleavage of covalent bonds, releasing water (which hadn't existed in tact before the dehydration), and an entirely new molecule (or substance) that is the anhydride.Copper sulfate can form beautiful blue crystals of the pentahydrate: CuSO4•5H2O (made up of an ionic lattice containing a Cu2+ ion, an SO42– ion, and 5 molecules of H2O). On strong heating, the water molecules evaporate out, leaving anhydrous copper sulfate: CuSO4CuSO4•5H2O --> CuSO4 + 5H2OIn contrast, acetic acid (H3CCOOH) can be dehydrated under very forcing conditions to make water (H2O) and acetic anhydride (H3CCOOOCCH3):2 H3CCOOH --> H2O + H3CCOOOCCH3In the same sense, sodium oxide is the anhydride of sodium hydroxide:2 NaOH --> H2O + Na2Osee the attached diagram.As you add water to most of the chemicals above, you get different compounds at different ratios of water to original chemical. That should highlight that the perfect formula is just an indicator of one or some of the reactions taking place. By stating a certain reaction you are claiming some exact ratio, which you do not state. You state some perfect mathematical solution. Solid sodium hydroxide has free water present in it. The reason is it is partially crystalizing in that state. Even though it is very hungry for water, and the addition of a lot more water creates the products we use in industry clear lye.It is certain that actual chemical reactions are much more complicated than the simplified formulas and equations that are written out. But that doesn't mean that these formulas and equations are useless, and it is certainly not an excuse to be sloppy about definitions.Please note that I did, in fact, include the ratios, which are meaningful.Quote from: William McC on 10/09/2016 14:14:19All of these chemicals and reactions create different chemicals different compounds at different levels of hydration. In industry and in life so many times people think the pure product is more potent while in pure form. However it is the action and reactions created with the addition of water that cause the effect it was designed to cause. So by using enough water, a weakened watered down solution, the product actually works faster and more powerfully. Lye is like that. When you put a very watered down solution of lye on oxidized aluminum, the reaction and heat liberated is really amazing. It totally cleans and brightens the aluminum. However you need the excess water to create the reaction. These reactions are always misstated by chemistry. And because the reactions are too complex to actually and totally understand, by placing a formula or reaction upon them, they rule out the factory accidents that occur by the actual complex reactions that are actually taking place. Congratulations, you understand that solvents play an important role in chemical reactions.Quote from: William McC on 10/09/2016 14:14:19I do not agree with your explanation. I believe you are stating a memorized understanding. Having worked with the EPA I saw that their college trained chemists did not understand chemistry. Because many plating companies had 8th grade chemists that could literally take what the EPA thought was dangerous hazardous waste, and turn it back into water that they would drink, and pure chemicals that they reused again. These plating companies had to pay for carting empty drums of waste that the EPA chemists thought was a byproduct of a certain reaction, even though the plating chemists could reclaim that material as they used it. These 8th grade chemists could plate up or down. By using a substance with a siamese bond and usually an oxide or chloride atom, they could plate that material up to or down to the element just above or just below. It was more of an art rather than a simple mathematical formula. However they did it everyday. If you look at plating tanks in the dark you will see they create light from the reaction taking place. It was explained to me that there was an atomic level reaction taking place. This was so true that some poor plating shops were creating radio active substances in their plating tanks from ordinary chemicals that are not radio active. So in some cases the EPA was right, and in all cases the 8th grade chemists that knew all of the above were correct I guarantee that I have a full, working understanding of chemistry, and my education was not just memorizing introductory texts (and I believe that Bored chemist is well educated on the subject as well). In addition to having a college degree in chemistry, I spent 6 years earning a PhD, which involved over 16,000 hours spent working in the laboratory (using chemicals like Na2O and NaOH, so I have an intimate knowledge of the difference between the two), followed by two years of postdoctoral research (another 5000 hours of labwork), and now am a principle investigator (still doing chemistry).You obviously have had some exposure to chemistry, but still maintain a very limited understanding of it. So please stop pretending to be a source of knowledge on the subject. In addition to being confused on the difference between molecules, substances, mixtures, and solutions, you also were apparently easily convinced that light emission was proof of the formation of radioactive substances from non-radioactive ones, when this is highly unlikely, and there are several other much more reasonable explanations.I sincerely hope that you are not responsible for drafting or enforcing EPA regulations.