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Everything posted by UC

  1. UC

    Ethanol wt% to vol%

    You're biggest problem is that a volume of ethanol added to a volume of water does not make a volume equal to the other two volumes you just added, and the amount of volume contraction has a lot to do with the proportions. If you use the volume of the input stream and the specific gravity (density), you can calculate the mass of the input stream. Volume x mass/Volume = mass. Then, apply the wt% you measure to figure out what the total mass of ethanol present. Using the specific gravity and volume of the waste stream, figure out how much ethanol is not being recovered. Then, you need the density of anhydrous ethanol and you have your number.
  2. There are two factors that govern boiling points. The first is the kind of bonds that the molecules can participate in and the second is molecular mass. Different kinds of intermolecular bonds can be formed, and if the liquid wants to boil, these bonds need to be broken, which requires energy. The stronger the intermolecular bonds, the higher the boiling point. Mass is also important, since on a molecular level, temperature is a measure of the kinetic energy of the molecules, and kinetic energy is dependent on mass. Think about it this way: It takes a lot more effort to keep an elephant airborne than it does to keep a balloon floating. Or something like that. I never was very good at anything physicsy.
  3. Big hint: start with a wittig reaction to make styrene. SN2 will be important later on. Think cyanide.
  4. Oh it's real simple. Just heat the MgO with molten sodium, potassium, or lithium under argon.
  5. Am I the only one who finds it hilarious that you're all responding to a 2 year old post? confused apparently felt it necessary to necro the thread for a one-liner with no content. Anyway, it should be possible to use a solid cast or machined paraffin block with some additives as a fuel source, using a separate chamber of liquid or gaseous oxidizer. Nitrous oxide could certainly work and perhaps the canisters sold for whipped cream could be utilized in some way. The rate at which the oxidizer is released into the combustion chamber would be critical, making this a far more advanced project (and much more interesting in my opinion) than a rocket using KNO3 and sugar.
  6. Tin will react with HCl without heating, but the reaction is slower. If you use concentrated HCl, it will go faster no matter what temprature. Moderate warming should help it along nicely without sending acid spatter and fumes everywhere. I'd use excess tin (so lots, and when it stops bubbling, just use the liquid as is). If you store it in an airtight container with a little extra HCl added, it should last a very long time. Making crystals is tricky and not worth the effort if you just need a solution to test with. If I needed crystals, I'd buy them to save myself the trouble.
  7. Look up the mechanism for thionyl chloride acting on carboxylic acids. Oxalyl chloride behaves exactly the same way, except you need to put one more arrow in. It's a little tricky and not necessarily intuitive, so looking it up is probably the best way to go.
  8. UC

    nuclear reaction

    Actually, beta decay would convert potassium into calcium... [ce] KCl -> CaCl^+ + e^- [/ce]
  9. The older reference used sodium amalgam and concentrated NH4Cl solution. I see no electrolysis. Take note that this reference is for quaternary ammoniums and uses electrolysis. Perhaps the result of the older procedure contained a small fraction of the ammonium compound, but would have been far from pure.
  10. You do have a point. Glycerol undergoes dehydration to generate acrolein, which is quite toxic and oxidizes to acrylic acid, which is also toxic. I suspect that as a gel, it would not be a clean burn at all. Probably rather sooty, since it isn't being force-fed oxygen to complete the combustion. If you were to solvate it in methanol and spray the mix into a burner system, sure, you could get it to burn completely without toxic fumes.
  11. UC

    good passwords

    I do the same, using names of my favorite chemicals. If the password allows, they often have hyphens and commas as well. Some of mine are in the 30s as far as numbers of characters. Examples (not my actual passwords): diethyleneglycoldibutylether 1,2,4-trichlorobenzene coppersulfatepentahydrate dinitrogenpentoxide 6-bromoindole
  12. superbases? try wikipedia by definition, they are all water reactive.
  13. That would be an electrophilic aromatic substitution, as described here: http://www.cem.msu.edu/~reusch/VirtualText/benzrx1.htm The HSbF6 is fluoroantimonic acid, the strongest superacid known. It is powerful enough to protonate simple alkanes, so phenol and bromine should be pretty easy. [ce] Ph-OH + HSbF6 -> [Ph-OH2]^+[sbF6]^- [/ce] The phenylhydronium ion there would behave like a nitro group, explained in the reference I linked you above. Therefore, substitution would occur preferably on the 3 position. Since HSbF6 is such a strong acid, you can safely assume that virtually all of the phenol is protonated all the time. The bromine is also probably protonated on on end of the dimer, which induces a dipole moment and drives the electrophilic aromatic substitution reaction. As for safety (from wiki): HF-SbF5 is rapidly and explosively decomposed by water. It reacts with virtually all known solvents. If you're even vaguely considering working with this stuff, don't.
  14. You can actually, but nothing you'd be able to make a ring from. Diamond-like carbon coatings are available under certain conditions by electrolysis of alcohol solutions, and poly-(hydridocarbyne) (a precursor to lonsdaleite (hexagonal diamond)) can be prepared by electrolysis of bromoform in acetonitrile with a salt (LiBF4 perhaps) added to aid conduction.
  15. Sorry, that wasn't directed at you. I'm know you know, but should I have left it uncorrected?
  16. You seem to be confusing simple high school level inorganic chemistry with all of chemistry. There is no sharp line. There are carbocations of all kinds, polyatomic chalcogen cations, metal clusters, substituted and quaternary ammoniums, ylides, phosphoniums, all manner of metal complexes, etc. There is also no hard line between ionic and covalent. Things can have partial positive charges and solvent choice makes a world of difference. Actually, a "single displacement" reaction is a redox reaction using an element. A double displacement is a metathesis reaction, and as far as inorganics go, it's only considered to have happened when there is a precipitate. If you wanted to do the reduction of say hexachloroplatinate anion by hydrazinium sulfate, I think the high school way to look at these reactions would crap its pants. Then there are olefin metathesis reactions using things like grubbs' catalyst, but let's not get into that.
  17. Insulated wire, please. Otherwise, it just shorts out.
  18. I would read up on equilibria and standard enthalpies of formation.
  19. I did this with some stannous chloride solution with tin anode and graphite cathode and it works great as well. I got something similar to that strange stuff, which i think had to do with the breaking of electrical contact with some crystals (the solution was still acidic to prevent hydrolysis) and small amounts of antimony in solution.
  20. Well, depends how much nitric acid is left. If you aren't dissolving any more silver with hot acid, I think it would be fine to just cool, pour off the liquid and use it directly. Otherwise the copper and very fine silver crystals will dissolve.
  21. Since when? You're missing a vast amount of chemistry somewhere. That sounds exceedingly dated. I suspect the main component is sodium amide.
  22. UC


    The internet is a good place to find ways to hurt yourself. If you just want to watch something burn, make a campfire. Thermite is not *that* impressive. However, it is extremely hazardous, especially for someone who 1) clearly has no grasp on the concepts behind the reaction and 2) seems to just want to goof around. If you do something wrong with thermite, it'll sling molten iron around, maybe all over you. Water won't come fast enough to save the body part it lands on and it certainly won't stop the main reaction. Try explaining that to the emergency room staff. Thermite can be handled safely, but if you need to ask here or anywhere else about how to make it, you shouldn't.
  23. You have two reductions. I'm not sure, but you may be able to do both with the hydrogen and Pd on carbon. Alternative to cyanohydrin: http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0221
  24. Ultra pure water has a very high resistance. Any electricity you try to pass through it either doesn't flow at any meaningful rate or has effectively all of it's energy dissipated as heat. When you add ions that can ferry charge, you allow current to flow and the energy is instead (some of it at least) used up breaking H2O into H2 and O2. When you burn the H2 and O2 again, you get back *all* of the energy that went into splitting them (but none of the energy lost to the water's still present resistance, or dissipated in the wires or internal resistance of the power source). No engine can harness all of that energy, in fact, it will lose the majority of it as heat to the surroundings. Overall, you lose most of the energy you put in with the original electric current.
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