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John Cuthber

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Everything posted by John Cuthber

  1. In a compound the constituents are generally present in fixed ratios, for example in salt NaCl there are exactly as many Na as ther are Cl. For a mixture like white gold the components can be present in (more or less) any proportions. Also, in compounds (even those where the ratios are not constant- the so called nonstoichiometric materials) the components generally have defined places in the lattice or molecule.
  2. Chemsiddiqui, Asbestos is banned in quite a lot of the world so I doubt that you need it. the rockwool stuff used as insulation may well do the job. When you wrote "hi, we were at the laboratory last week trying to do some of the chemistry experiments in the college? but we could not do it beacuse we did not know what exactly was mineral fibre and ceramic fibre. " what were you hoping to do? We might be able to help better if we understood better.
  3. I rather doubt the pins were ever pure gold. It's so soft the pins would buckle rather than plug in. (Though I agree it would have been better if Tater had read the thread).
  4. "the honey you buy at the store(if it is a really cheap brand)is only made out of high fructose corn syrup and coloring agents depending on the type of honey that you buy." I doubt that because food products are usually quite well regulated and a product made like that simply wouldn't taste of honey. I'm also left wondering if you really thought that we had been waiting since last October for your wisdom on this matter.
  5. Perhaps you should have read before you posted.
  6. If there were, lots of us would be making it, undercutting the other suppliers and making money.
  7. All you need to do is work out how much more HCl you need to add (easier said than done because the volume will change).
  8. It's a fair question; do those difluorides (of 4 valent elements) exist for any length of time?
  9. Are you sure? It seems to me that an expression for an area should have a term which is second order in length. If I double the length of the side the area should quadruple rather than double.
  10. Freeze drying is not the same thing as freezing out the water and pouring off the alcohol etc. For freeze drying you cool the material until it has all frozen then drop the pressure to remove (by sublimation) anything that's volatile. If you did this to beer you would lose all the alcohol and qiute a lot of the flavour.
  11. Dalton's law says that the total pressure is the sum of the partial pressures. In this case 565+225 ie 790mmHg
  12. Most people won't have a clue what you mean if you are talking about nitrites anyway ;-) At least most of the chemists ought to understand if you use the full IUPAC names (Though at this point I usually ask "What's the systematic name for sucrose?" and run away while people try to work it out). Unfortunately the problem is that nomenclature has to do two opposing things- it has to uniquely identify a compound (and I think that even "potassium tris-oxalato chromate (III)" doesn't do it because there are optical isomers) but, at the same time, it has to be simple. I doubt it's possible for it to do both so we just have to muddle along with it. Anyway, I have to get up early so I'm off to bed. Bye.
  13. They called high oxidation states "per" before they had any idea of the nature of the O-O bond in H2O2 The idea that it should only be used for compounds with a bond between two oxygens is relatively new. If you really want to use the new terminology then you are looking at trioxynitrate(V) for the common isomer and (I think) oxy-peroxy-nitrate (III) for the red one. The prefix "per" is not derived from peroxide but from Latin meaning "beyond" Peroxides were beyond the normal oxides eg Mn and Pb (IV) oxides rather than the PbO and Mn2O3 that were normally encountered and H2O2 rather than H2O If you wish to make the distinction then things with O-O bonds should be called "peroxy".
  14. Strictly carvone and geraniol are terpenoids rather than terpenes (Beacuse they are not hydrocarbons) but since that means I can say that my favorites are linalool (and its acetate) and Patchouli alcohol (A sesquiterpenoid if anyone is being fussy) I will let you off.
  15. We were all new to it at one time.
  16. EW_ oxidant = molecular weight or formula weight of the oxidant/ number of electrons transfered This is a bit awkward because the number of electrons transfered depends on the conditions. For example KMnO4 can transfer 5 electrons in acid conditions to give a Mn++ salt or 3 in near neutral conditions to give MnO2 or, in rather strong alkali it can accept just one electron and give the green MnO4-- ion. That means the equivalent weight of KMnO4 is 158.03/ 5 or 158.03/3 or 158.03 depending on the conditions. It's no wonder that equivalent weight and Normality have been largely replaced by Molecular weight and molarity. A solution of 158.03 g of KMnO4 in a litre of water (I'm not sure if it's that soluble- but that's not the point) could be labeled as "N", "0.2N" or "0.3333N" depending on what was going to be done with it. However it would be one molar no matter what.
  17. The spam bots have probably harvested your email by now and will send you endless trash. The PM system seems to work perfectly well so I really wouldn't recommend putting your email here. The "lepton" thing is a light hearted way of indicating how much stuff you have posted- "leptons" haven't posted much, "quarks" a bit more and so on. BTW, the lowest oxidation state oxy-acid derived from chlorine is hypochlorous so you end up needing lots of names and prefixes to keep track of them all. hypochlorous/ hypochlorite; chlorous/ chlorite; chloric/chlorate; perchloric perchlorate. I personally think the IUPAC names are ugly, but I can see how they are easier to remember. For what it's worth, the "per" in peroxide means the same as the "per" in perchlorate so the name "perchlorate" is correct. A peroxide contains "more than the usual amount of oxygen"- so does a perchlorate or a persulphate. One could say that persulphate is wrong because it should be peroxysulphate. HClO
  18. The recovery of gold from old computers is often done in very poor countries where labour costs are very low and the environmental impact of the process is simply ignored.
  19. They don't seem to be easy to find out about. This http://www.springerlink.com/content/w60054l7wu642728/ gives some data on the first dye and the last experiment here http://www.mtholyoke.edu/courses/menunez/Chm302OrgIIWeb/Labs1-6.pdf might be interesting too.
  20. Actually, as far as I can see when there's only one possible one they are called -ic acids like carbonic boric and (a bit obscure), silicic but I don't know if there's really a good reason for this- just convention.
  21. My understanding of perfect pitch is that you would be able to connect a microphone to a frequency meter and whistle/ hum "concert pitch A" (without looking at the meter) and the meter would read 440 Hz exactly. Can you do that? Perfect relative pitch is another matter, given the 440 Hz start even I can get pretty close to 880 Hz or 220 Hz (the octave up and down). I'd struggle to do the notes in between the octaves (Hey! I'm a chemist, not a musician)
  22. It looks to me like a matter of definition. "The photon has zero invariant mass " The need to qualify the variety of mass that a photon lacks as invariant implies that there is some other sort of mass (presumably variant) that a photon does have. OK so a photon at rest has no mass. A photon "at rest" does not exist. (Even allowing for "stationary" photons in Bose Einstein condnsates, if it's "at rest" from your point of view it's doing roughly 1000 MPH from mine because I'm on the other side of a spinning plannet.) Can anyone explain why that pair of statements is inconsistent with the assertion that no photon which exists has zero mass? Anyway, the mass or lack of mass of a photon (at rest or otherwise) doesn't matter in terms of answering the question "how can we create a true vacuum (impossible), with something that has mass(that cannot go the speed of light) and go the speed of light (thus a paradox) to accurately measure the speed of light?" We don't need a true vaccuum to measure c. (Though actually I think I may have made a mistake in my answer yesterday; I think you need to plot 1/c vs p and extrapolate to p=0 then calculate c)
  23. A spot of searching for "surface tension" might help you here.
  24. "I think the first one is something simular to an aldol condensation. Actually I'm nearly 100% positive it's related in some manner." I'm pretty certain that it's not (other than that it forma a carbon carbon bond). I also wonder if you actually looked into the chemistry of pinacol. Even a google search on the word might have helped, and I think the 'net's really quite good at that sort of thing.
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