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  1. The purity of the metal is important! I have some zinc rods and copper foil of analytical purity. These samples does not show any surface oxidation when stored in air. But technical grade pieces of the same metals are rapidly oxidized under the same conditions! Purity is vital.
  2. I once tried to clean a piece of neodymium. The metal is easily etched with diluted HNO3, and the surface is cleaned with water, and dried with acetone. Immediately after, I polished the surface with polishing compunds, resulting in a mirrorlike surface finish. But there the luck stopped. I immersed the shiny metal under paraffinum oil, but the metal corroded heavily within years. Nothing could stop the corrosion on depth. Even sodium behaves (and is preserved) better than Nd for a long time immersed under paraffinum oil! When I purchased the lanthanide metals from David Hamric (eBay, "rare earth metals set"), I observed the same problem within a year. Finally, I solved that problem by simply purchasing La,Ce,Pr,Nd and Eu as metal pieces in sealed glass ampoules under argon gas (most of these also from Hamric). My experience is that the reactive lanthanides should be kept under Ar in sealed glass ampoules. These metals should NOT be kept under paraffinum oil, at least not for an element collection. The heavier lanthanides (from 66 Dy up to 71 Lu) does not corrode in air. Sm corrodes slowly, and the commercial metal is often oxidized on the surface. Gd also (and to some extent Tb), but much slower.
  3. Stains of MnO2 on organic matter, from exposure to KMnO4-solutions, can be very efficiently removed with slightly acidic water solution of sodium sulfite. Caution; the solution emits toxic and highly irritating vapor of sulfur dioxide, should be kept in a well ventilated area! The stain of MnO2(s) is immediately reduced by the sulfite ion in acid solution to water soluble Mn2+. The stain is removed. Have tested it myself; even stains more than a month old are completely removed. About chemical burns. The most painful burn experience I have is not from acids or alkalis, but from formaldehyde (40% H2O-soln). Extremely painful. One of the most dangeorus chemicals in this respect is hydrofluoric acid. Causes deep painful burns, even necrosis.
  4. Activity. I somewhere got the information that natural carbon (containing a small amount of C 14) have an activity of about 237 Bq/g. Taking into consideration that a person of 75 kg contains about 17250 g of carbon (see webelements), this means that a human being emits a lot of radiation: 237 Bq/g * 17250g = 4 088 250 Bq Well, compared to ourselves we don´t have to worry so much about a piece of Re, and even less about a piece of In. And certainly not Bi!
  5. I stand corrected! This means that there are two, not one, elements with at least one stable isotope, but with a natural isotopic composition dominated by an unstable isotope. However, the half life of In 115 is extreme even compared to Re 187 (4,35*10^10 yr). Consequently, the acticvity of natural In is almost none compared to natural Re. A difficult question arises: how long half life can be detected? I have seen claims that Bi 209 is unstable, with a half life of ~2*10^19 years!! Then what will the activity of Bi 209 be? The half life of Bi 209 is roughly 5*10^8 times the half life of Re 187, consequently the activity is (~1000Bq/g)/(5*10^8) = 2*10^-6 Bq/g. And this means about 1 radioactive decay in 6 days (in 1 gram Bi)! How do you detect that??
  6. And more... ...oddities. What was the fuzz about "red mercury"? I once saw that it was a compund Hg2Sb2O7. And the use was claimed to be in - nuclear devices! It was said to "enhance" the nuclear reaction. Of course som people tried to smuggle this stuff from Russia, when the Soviet Union fell apart.
  7. Suspicious When talking about PGM, I remeber that I have seen even now on the net some strange suppliers offering Os 187, for half a million dollar per gram! But why on earth spend a lot of energy (and money) on separating the Os isotopes? What is the use of this isotope? Does not make sense.
  8. One odd thing about Re. It is the only element with at least one stable isotope, but with a natural isotopic composition dominated by an unstable isotope! I once calculated the activity, it is slightly more than 1000 Bq/g metal (natural isotopic composition). This should be compared to U 238, with the activity slightly more than 12300 Bq/g. But natural Re is not classified as radioactive material, maybe because of the very low energy. Actually it is very difficult measure of the radiation accurately, because of the low energy.
  9. Rhenium Unfortunately, my platinum metal ingots are just small 1g samples. Will do for a while. But once I got the opportunity to buy a very special form of rhenium ingot. A swedish guy once produced large amounts of rhenium (metal and perrhenate) for industry, the production ceased in the 80:s. But from this production he got som small Re flakes which he collected. And at the end he had about 100g if it. So he made a sintered ingot of these flakes, and arc melted this ingot under argon. The result was a cigar shaped ingot of a bit more than 100 g Re. Purity was analyzed to be at least 99,93%, the main contaminant is tungsten (the material of the other electrode). He offered me a piece of this ingot. I purchased a piece of approx 15 g. The interesting thing about this piece is the different surfaces. One surface is the arc discharge surface, where the crystalline metal surface have a very prominent crystal structure. The surrounding side are slightly oxidized, but still shiny. The back is where it was cut of from the large ingot, so the shiny metal surface is exposed. And a small sharp edge where the ingot was finally teared off by force, resisting mechanical tear. Must have been a tough task to cut and rip off a solid piece from that ingot. This piece shows a set of surfaces and edges, even crystalline metal surface, treated in different ways. The ingot feels incredibly heavy, with almost twice the density of lead. Much more illustrative than a thin metal foil would be.
  10. One ounce?? Of each of the platinum metals? Eh..., that will cause som pain in the wallet, I assume. In my wallet it would. I saw your pictures, a beautifull collection. How much did you pay for that huge Ir ingot? Impressive. The only platinum metal I purchased in larger quantity was palladium many years ago. It was a rather low cost metal in 1981, about $90 for a one ounce Credit Suisse ingot. Today that ingot would be ...expensive, to say the least. But I am thinking of buying some larger ingots (~10g) from Hamric. Some other metals I would like to have in 100g ingots are the lantanindes. Smart-elements have 100g and 200g lots of the reactive lantanides under argon at a low cost: http://www.smart-elements.com/index.php?element=Ce&arg=show&PHPSESSID=2abe2474a4309c7383e74f9d8df8cf96 *digging in my wallet*
  11. About Svenska Kemi They offer a complete set, "all the natural elements in a box". But I strongly suspect that it is an imported version of the RGBco set, found here: http://www.element-collection.com/index2.htm
  12. Gilded No, actually I have made all of my element purchases the last 5 years through eBay. The best one is Hamric: http://search.ebay.com/_W0QQsassZhamric In almost every case he enclose a certificate of analysis. Only a few exceptions. He also very clearly informs about the shipping rules according to USPS publication 52. Because of this some few elements are shipped to United States only. Examples are Ca and Ba. Another excellent seller is Emovendo: http://stores.ebay.com/Emovendo_Elements_W0QQcolZ2QQdirZQ2d1QQftidZ2QQtZkm Some more common metals (Al,Zn,Pb etc), very low price: http://search.ebay.com/_W0QQfsooZ1QQfsopZ1QQsassZourQ2dhousecatQQsojsZ0 And some special items:Silicon wafers: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4660&item=7505136124&rd=1&ssPageName=WDVW (Try a search for "silicon wafer*") In Sweden there is som domestic auctions sites ("tradera", "blocket"). I have never found any elements there! Where on the planet can I find anyone selling osmium, not as the usual dirty black powder, but as solid metal pieces? The answer is eBay! Even 1kg ingots of solid praseodymium!
  13. Sorry! I was somewhat unclear. I mean that I have tried to use Laplace transforms and inverse Laplace transforms, to derive an inverse to the gamma function. Like this: [math] \ Gamma (n+1) = n! = \int_{x=0}^{x= \infty} x^n e^{-x} dx [/math] with inverse: [math] \ Gammainverse (n!) = n+1. [/math] But what is the explicit formula for Gammainverse (an integral, etc)? Could it be of the form: [math] \ Gammainverse(s) = \int_{t=0}^{t= \infty} f(s,t) dt [/math] with f some suitable function? If so, how do I prove this? With any integral transform? That is what I have failed to derive.
  14. I agree that the hair dye example is not the best. Maybe better examples: Some silver polish solutions contains rather high concentration of thiourea; carcinogenic. And I have seen insect repellants with up to 15 % of derivatives of aromatic diamines. Definitely carcinogenic.
  15. For nitration purposes in organic chemistry "nitration acid" is often used, a mixture of HNO3 and H2SO4. In this mixture, the HNO3 actually acts like a base(!), producing nitryl cations, (NO2)+. This is the specie attacking organic molecules. In this acid mixture, the sulfuric acid acts like a strong acid, even together with nitric acid.
  16. It is another way of formulating the energy principle: energy cannot be created or destroyed. Therefore, the difference in energy between 2 states cannot be dependent of the path. If that was the case, the total energy (that is final energy - start energy) would give different results depending on the chosen local path. Then energy would be created or destroyed somewhere along the path. In theoretical physics they talk about conservative force fields, and potential functions. The same stuff, different terms.
  17. 1. The molar ratio HCl:HNO3 is 3:1. But if you calculate on the concentrated acids, their molar konc etc, the VOLUME ratio between the commercially available acids will be 4:1 ! Remember that konc HCl is ~35%, and konc HNO3 is ~65%. 2. The acids react to form a water solution of nitrosyl chloride (NOCl) and chlorine. The originally colourless mixture is soon going yellow and dark orange red (by the NOCl), and emits an intense smell of chlorine. Fume hood is needed, goggles and gloves too!!! I did notice a tiny temperature rising during the reaction. The mixture can be stored for a short time in a glass bottle, but there is a risk that both the components will be gassing off above room temperature. And consequently pressure increase inside a closed bottle! Should be stored for a short time only at low temp, unstable even in cold. Aqua regia is most often used freshly prepared because of the decomposition. I have spilled drops of this liquid on the skin, gives the same local burns as any strong acid. Wipe of immediately, rinse with plenty of water. 3. The violent reactions occur when the liquid come in contact with reducing agents/easily oxidizable substances. Metals, even noble metals, are rapidly attacked, producing either soluble chlorocomplexes (Au gives (AuCl4)- in solution) or insoluble chlorides (Ag gives AgCl(s) ). Some of the reactions are violent; once I tried reaction with Sb, and that was certainly violent!! Other reactions may be slow (Pt reacts a lot slower than Au). Only a few metals are not attacked by aqua regia, like Ir, Ru, Rh. Especially Ir withstand attacks from all acids even when finely divided. When working with aqua regia, always use goggles, fume hood, and only small amounts (maximum ~10 ml). Should be freshly prepared.
  18. The difference in base strength of the alkali hyrdoxides is small. Even LiOH is a strong base, and attacks glass. Alkali metal oxides are stronger bases than the hydroxides. And nitrides are stronger bases than imines, which are stronger than amines, which are stronger than ammonia. Another group of strong bases (base strength approx as alkali metal hydroxides) in water solution is tetraalkyl ammonium hydroxide, R4NOH, R=alkyl group.
  19. Well, actually; yes I would! If I buy a piece of wood, I won´t get a MSDS saying that "sawdust is dangerous to your health and may cause cancer". And if I´m buying a piece of aluminum tubing, it would be inapplicable to receive a MSDS that says that "aluminum dust is dangerous to inhale, and may present a fire and explosion hazard". Even more surprising is the double standards about chemicals in household articles. I am not allowed to buy some pure crystalline paraphenylene diamine. Carcinogen and toxic etc. But I can buy a bottle of black hair dye, containing the same toxic chemical. I would like some logical consistency in the field of chemistry, pure and applied.
  20. Particle size certainly is important for reactivity. Zr and Hf usually are produced as very finely divided powder. In this state these metals are pyrophoric, and are stored and handled under water. But the solid, compact metals are very resistant to corrosion. They are practically impossible to ignite in solid form.
  21. Although Alfa Aesar is very expensive, their MSDS search is a really good service. And it is for free! http://www.alfa.com/alf/msds_search.htm This is one of the very few sites with MSDS about europium, osmium and other unusual elements and compounds.
  22. Well, I don´t know about the accuracy of the MSDS. 24 years ago I purchased a glass ampoule of 2 grams of Sc, and a palstic bottle with 20 grams Y from Johnson Matthey. (today, the same stuff from the same company would be tremendously expensive!). The MSDS said that yttrium metal was pyrophoric! Oops...! Well, I tried a small piece of yttrium in a bunsen flame, and waited for the metal to ignite. It didn´t. Not even at red hot temperature! The metal piece oxidized (not surprising) but never ignited. So much for that hazard. I have a MSDS for bismuth saying that it is sooo dangerous... If you buy a piece of lead pipe in a hardware store, you just pay for it and go. But if you buy the same piece of lead as a laboratory chemical, it´s suddenly classified as extremely hazardous, carcinogen, toxic, etc, the purchase has to be registered and controlled, the seller need an endless amount of permits and applications etc etc. Thats the world of chemistry.
  23. Does it exist any explicit formula for the inverse of the gamma function (within some suitable region)? I have (without succes) tried to derive an inverse with Laplace transformation, the inverse of Laplace transformation, other integral transformations, with functional equations, etc etc.
  24. Somewhere I have an old catalog from Ingal GmbH, a german company in Schwandorf extracting gallium from aluminum source (bauxite). I remember a small note at the end of the catalog, saying that Ga with a purity of at least 6N is considered strategic material by the SEATO treatise! Probably the use of Ga in the semiconductor industry that is the reason for this. I don´t know what this really means if you try to purchase some of this material. Maybe some formal permit applications, checking out by some authorities? However, Ga 4N is certainly pure enough for any chemical and element collecting purposes. Ingal GmbH does not exist today, it was bought by Rhodia (former Rhone-Poulenc) some years ago. Seller of Ga 6N: http://www.emovendo.net/store/customer/home.php?cat=255
  25. Sulfuric acid readilly absorbs water from organic material even at room temperature. the absorbation is exothermic, as observed when mixing the acid with water. At elevated temperatuers, the organic matter is simply destroyed by the acid. Sugar is chemically decomposed when the acid absorbs water, and the residue is mainly carbon (coal). The same applies to paper (cellulose), and also in this case the residue is coal.
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