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John Cuthber

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Everything posted by John Cuthber

  1. If there were, lots of us would be making it, undercutting the other suppliers and making money.
  2. 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).
  3. It's a fair question; do those difluorides (of 4 valent elements) exist for any length of time?
  4. 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.
  5. 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.
  6. Dalton's law says that the total pressure is the sum of the partial pressures. In this case 565+225 ie 790mmHg
  7. 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.
  8. 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".
  9. 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.
  10. We were all new to it at one time.
  11. 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.
  12. 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
  13. 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.
  14. 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.
  15. 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.
  16. 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)
  17. 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)
  18. A spot of searching for "surface tension" might help you here.
  19. "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.
  20. Is this "Transfusion blood is heated in water, not a microwave oven. Why? Because if heated in a microwave, the blood becomes toxic and more than one patient has died as a result." backed up by any peer reviewed data? If someone died was it due to tocicity or to local overheating causing clotting? Is this just an urban myth?
  21. Actually photons have mass. It's given by E=MC^2 and E=hf. (Energy, mass, speed of light, Planck's constant and frequency) They are atracted by gravitational fields (The effect is usually refered to as "gravitational lensing"). They also carry momentum and exert radiation pressure. There is a cop out on the "nothing can travel at the speed of light" What is forbidden is accelerating anything with a rest mass (ie a mass, even when it's stationary) to the speed of light. Photos have zero rest mass (a slightly meaningless idea since a photon at rest doesn't exist). The fact that we cannot produce a perfect vacuum does not stop us being able to establish the speed of light in a vacuum. That sounds like a paradox, but it isn't. We can measure the speed of light in air at one atmosphere pressure, we can do the same at half an atmosphere, a tenth, a thousandth and so on. Then we can plot a graph of speed vs pressure and draw a straight line through the points. We can carry that line on until it hits the axis for "pressure = zero" and read the value of the speed in a vacuum from that. I hope this answers your question.
  22. ecoli, What aldehyde and what triple bond? The classic method for the first part, IIRC, is reduction by magnesium. Look for stuff about pinacol. I'm not sure abouty the second; perhaps dehydration to the epoxide then reduction?
  23. Try this page (In general, try using a search engine) http://polymer.matscieng.sunysb.edu/OH_handouts/polyFoam.doc.
  24. I think this http://www.mutr.co.uk/prodDetail.aspx?prodID=1194 thing about memory alloys is about as close as you will get.
  25. Quite a lot of chemicals are worth taking the trouble not to get on the skin too. Of course, provided that you don't come into contact with the Br2 it's also safe for experimenting. All chemicals are safe as long as they aren't anywhere near you. (Explosive and radioactive ones can get you at a distance.) Fundamentally, (and this is an important point) there are no dangerous chemicals. There are lots of dangerous things to do with chemicals and for some chemicals there's a bigger choice of dangerous things to do than others, but the danger is a matter of what you chose to do with them- not a property of the chemical itself. A beaker of NH4Br isn't a bigger problem than a beaker of NH4Cl. On the other hand, if I wanted to make some smoke I'd use the chloride unless I had a really good reason to risk the neurotxicity of the bromide (and possibly the carcinogenic bromate too)
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