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Posts posted by UC

  1. Water vapor and ammonia are not ideal gases. Ideal gases make the assumption that there is no interaction at all between the gas molecules. This is only a model (a flawed one for most cases) but is a good approximation of the noble gases and things like nitrogen or hydrogen, especially at low pressures and high temperatures.


    Dimethyl ether does not have a hydroxy group. The hydrogens that it possesses are bound to carbons and are essentially nonpolar. Ethanol, however has an OH group, which is polar and can participate appreciably in hydrogen bonding.


    Think about it. Benzene has hydrogens, but it won't dissolve in water, which has oxygen lone pairs. If the benzene hydrogens could participate in hydrogen bonding, dissolving in water would be quite favorable, but that is clearly not the case.


    The enthalpy of vaporization of a liquid represents the energy needed to counteract all the IMF in the liquid state added to the energy needed to expand the resulting gas to it's final volume. For liquids that H-bond, the intermolecular forces represent the vast majority of the energy needed.

  2. [23:29] <UnintentionalChaos> I dont want admin necessarily, just hammer-swinging duty

    [23:29] <javagamer> In all honesty I think Sylar would probably make a pretty good admin, UC too


    The javagamer, it liesssssssssssssssssssssssss.

    ydoaPs can't be trusted with mop duty, much less admin powers.

  3. Thanks guys.


    I was wondering how dangerus is a 30% solution of hydrochloric acid, and what are some safe experiments i can do with it ?


    Safe is a relative term. 30% HCl fumes, and the fumes will rust anything made of steel in the same room as it. The containers they sell it in (hardware store muriatic acid) *do not* contain the fumes properly. It can cause pretty nasty acid burns if you get it on yourself, damage stainless steel, aluminum, steel, copper, brass, etc, and will choke you pretty nicely if you catch a good whiff of the vapors.


    Unless you have goggles, gloves, and good ventilation, don't use it. Some proper labware is in order. Pipettes, beakers, and glass stirring rods. You can't just slosh it around like vinegar.


    You need to store it properly, and glass bottles with teflon lined caps are a good choice, as it will damage some plastics. Something like this is ideal: http://cgi.ebay.com/Lab-Glass-Amber-Solution-Bottles-1-liter_W0QQitemZ140351540198QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item20ad9a8be6


    It becomes moderately safer if you dilute it with 2 parts water, so that the fuming is minimalized, but is still not to be taken lightly.

  4. The easiest way is to make an ester and hit them with stoichiometric DIBAH (diisobutylaluminum hydride).


    Or you can reduce them to the alcohol (LiAlH4, B2H6*THF, or the acid chloride with NaBH4) and then use PCC or PDC.


    Or convert the alcohol to the halide, treat with silver nitrite (for best yields. lower yields are obtained with alkali nitrites) and seperate the mixture of alkyl nitrite (generally the minor product) and nitroalkane.


    Use the nef reaction to cleave the nitroalkane to an aldehyde.


    You'll have to do some research, because it works decently with some alkyl carboxylates and horribly with others (and very well with benzoic acids), but the Stephen aldehyde synthesis takes a nitrile to the aldehyde by treatment with anhydrous SnCl2 in ether followed by aqueous quenching. There are a number of ways to make the nitrile from the acid.



  5. There is no easy way to do the conversion between the two. Since intermediates involving a carbocation are more stable for a secondary position than the primary position of n-propanol, interconversion is not favored.


    Reagents that generate a primary alcohol are quite expensive. You're better off seeking out some commercially available source.

  6. where did you get a supply of pure acetaminophen?


    Just a guess-


    Cheapo uncoated off-brand acetaminophen tablets are not hard to come by and it's relatively easy to recrystallize. The fillers and binders are only a small portion of the tablet weight and are generally insoluble in most solvents.


    Aspirin can be recrystallized in a similar manner, using hot acetone to extract the tablets. Slow evaporation gives large, transparent crystals in my experience.

  7. Well, school work's kept me back for some time, but I've finally managed to respond. The experiment itself went rather successfully, and by the end of the week, the solution had turned a lovely yellowish- golden colour (due to the dissolved sodium terephthalate) with insoluble plastic materials (whose size had greatly decreased due to reaction) and small amounts of undissolved sodium terephthalate at the bottom.


    I then proceeded to empty out my initial 250ml flask, into a larger erlenmeyer flask (a little over 500ml), and added water, dissolving the remaining sodium terephthalate. (I actually accidentally went a little too far, and wound up diluting it a fair bit (thus the more bland colour of the solution in my second picture). I then filtered the solution, the filtration process being rather slow towards the end, taking about half an hour.


    I have yet to actually add the hydrochloric acid to precipitate the terephthalic acid, but will do so when I have some more free time. I was thinking of purifying my leftover ethylene glycol solution, after that, but it would have to be done outside, due to the dioxane formed.


    A tad unrelated, but how would one go about making high purity dioxane from ethylene glycol. (Relax, I know dioxane is nasty stuff and that in many cases, there are numerous ethers that are far safer and equally efficient in solvation. It's more of an out- of- interest thing than anything else.)


    ps: I've posted the photos of this synthesis on my profile.


    Use a different acid. You risk making bis-(2-chloroethyl)ether if there is any diethylene glycol contaminant around. This is an analogue of sulfur mustards, and while not nearly as nasty, is still nothing you want to be dealing with.


    Dioxane is probably better made from diethylene glycol, by reaction with hot sulfuric acid, with continuous distillation of the product, analagous to the production of diethyl ether.

  8. REPLY: no one said genetic mutation is what causes a new species to emerge. Almost all mutations are either harmful or simply junk,not harmful or helpful and don`t express themselves. They are inactive genes. The genes alread exist within a species to produce another species. When for some reason the members of a species are kept appart and no longer exchange genes amongst themselves, create two seperate gene pools, given enough time two different species might emerge. This usually takes many generations. For slowly maturing species like whales,or deer,lions, it could take a very long time. Humans have lived in seperated gene pools for tens of thousands of years at a time and yet are still the same species. They can still breed with each other. Certain insects have been known to generate new species within much shorter time spands. As far as a woman and a man developing the same mutation and mating with each other ,the chances of such an event are so remote. It would also have to be a mutation that expresed itself and most do not. It seems it may have have happened with some bacteria over the billions of years. Whatever, ...Dr.Syntax


    Mutations are the ONLY source of new genetic material.


    Mutations are heritable, even though they may not be expressed. If the DNA being transferred to the offspring has a miscopied base pair, it doesn't vanish because the other parent didn't have it. It's still there. Very few features have "Mendelian expression" that you seem to be stuck on. Cumulative mutations over very long periods of time can result in the formation of entirely new structures, proteins, etc. Most mutations will be deleterious, and if natural selection is allowed to function, they will be "weeded out." Those that do not give an advantage are passed on at an average rate, where they can compound with future mutations. Those that convey a distinct advantage to reproductive fitness are passed on readily.


    Smaller numbers of mutations are unlikely to accomplish the formation of new structures, but can easily turn off normally expressed genes, or set them into "overdrive." Cancer relies on combinations of both, but these mutations (just based on probability) are often not in the reproductive cells, and many occur after childbearing years. In this case, they are not heritable.

  9. I use epsom salt everytime I get a bee sting (mild to mean allergy), there's no danger to it whatsoever to my experience.


    But I don't see it helping you lose fat in any parts of your body


    You're responding to a 3-years dead thread ressurected by spam. :eyebrow:

  10. In all science questions you always assume STP unless otherwise stated. The Answer IS D. Water IS blue NOT clear. Even in a glass it is blue - it just appears clear to us, it IS blue - the answer HAS to be D.



    A common chemistry question is "Why is water blue?" - ANS: Because of all of the free electrons in it.


    Facetious. Water just happens to absorb weakly in the red region of visible light. Heavy water (Deuteurium oxide) is completely colorless when pure. The change in isotopes has shifted it's absorption band further into the IR spectrum.


    Now dissolve some alkali metals in liquid anhydrous ammonia for me, and you can see free electrons. :cool:

  11. A superacid is an acid with an acidity greater than that of 100% pure sulfuric acid.

    Actually, the fluoroantimonic acid is 2 x 10^19 times stronger than H2SO4! It is the strongest superacid known (therefore the strongest acid), and its aqueous solution is about -25 in pH!


    HSbF6 decompses with much violence in water, hydrolyzing to HF and antimony oxides.


    10^19 times stronger just means that the proton is 10^19 less strongly attached to the rest of the molecule. pH relies on concentration of protons (hydronium ions) in water, and will never exceed the -log(conc), where conc is the molarity of the acid in solution multiplied by the number of acidic protons.


    In water, any acid with a pKa lower than -1.7 is effectively completely dissosciated, forming a "salt" if you will of hydronium ion (analagous to ammonium)


    How corossive acids are doesn't mean anything with regards to their strength. HSbF6 needs to be handled with all fluoropolymer equipment, simply because the fluoride is immensely corrosive to glass.

  12. gases can certainly exist as gases. Google manganese dioxide thermite

    Merged post follows:

    Consecutive posts merged

    also don't fluorescent lights contain mercury? is that metallic mercury? not sure...


    Mercury vapor. While it may not conduct any better than normal gas, once an arc is struck, the plasma is an excellent conductor. For a particularly awesome looking piece of equipment, google mercury arc rectifier.


    As for nomenclature, the gas may not participate in metallic bonding anymore, but it is still of a 0-valent metallic element.

  13. A good listing may or may not exist, but I haven't found one yet. Take some pics and I can give it a run-through and try to tell you what's what.


    Often there are bits of custom glass kicking around, which are anyone's guess.

  14. How would I go about cultivating the bacteria for it, just do my business in a bucket and leave it in a cupboard for a month?


    what about adding sugars to promote bacterial growth?


    Generally you'd use a heap of manure and other decaying matter, that is kept soaked with urine for months....as you can see, it's not exactly an elegant, simple, or clean process.


    Google some more on nitre beds if you're interested.

  15. Well the molten lye thing's out of the picture, so no worries John. And yes, I was thinking of something on the lines of Kolbe Electrolytic Synthesis, but you raise a very good point (Yay you!); I could instead decarboxylate the terephthalic acid later formed, with molten lye, rather than winding up with naphthalene, and other unwanted biproducts, via the Kolbe electrolytic synthesis. (Not fun.)


    However, if I do try out this method, it'll only be in a while, as I'm still in the process of making a new condenser/still for refining alcohols, benzene and whatnot, and benzene has a rather low boiling point (or at least certainly lower than sodium hydroxide).


    ps: I've started the experiment, with 150mL of 50% ethanol, and have added some sodium hydroxide and PETE flakes. I'll run the solution for about a day, then post the results. When I'm done, I'ld add some HCl, and see what my terephthalic acid yield was. Happy experimenting!




    You may need a few weeks to accomplish the reaction in aqueous ethanol. It can even be done without the alcohol, but takes longer still.


    The main point of the ethylene glycol is that you can heat it strongly, which speeds up the reaction.

  16. Thanks UC, I'll go buy a stainless steal pot for this one (or something of the sort). And no, there won't be any splashes. The only thing I'm worried about is ethylene glycol vapour, which boils before sodium hydroxide melts. I thought of using an alcohol- based solent, as it would be a lot safer, but I don't think the yield would be as good. I could try and plug any possible holes, but I'm worried of what'll occur if the ethylene glycol escapes. Of course I will be reared incapable of seeing what is going on, but it's just safer that way. I guess I'll probably run it for about 15 minutes, then leave it for an hour to cool, in an ice bath. Joy. :)


    Any thoughts? Concerns? Reasons to cry?


    Is this decomposing PETE plastic? It'll work better with some water in the mix and ethylene glycol or diethylene glycol solvent, trust me. If you fuse with lye, it'll make benzene instead.

  17. No, any silica glass (including fused quartz) or silicate ceramic will be attacked by molten lye. Stainless steel vessels are good for molten lye, but not if oxidizers are to be included. I recommend a cast iron crucible in this case, as a protective layer of magnetite should be formed.


    Molten lye with nothing added is surprisingly tame, but you need some serious protection if you want to add anything that may cause splashes or spatters.

  18. BaF2 is close to insoluble in everything. How do you expect it to color the flame if none of it will dissolve?


    Red from calcium? Orange from sodium? Huh? Calcium gives a nice orange in my experience and sodium is the ubiquitous yellow..


    You'd be better off spraying the solution through a flame, that way ensuring that the coloring agent is around when the alcohol burns. In a still dish, you're burning the fumes and the only way the coloring agent gets into it is by spattering.


    Cardstock burns yellow and is going to wipe out any other spectral lines you might see. A fused bead of salt on the end of an iron wire held in an alcohol flame should give you better emission for the difficult ones.


    Boric acid in methanol is great, because it forms trimethyl borate in equilibrium, which is volatile and can really color the flame a nice minty green. Ethanol is significantly less impressive and tends to give a mixed color flame of orange, blue, and green with boric acid, according to woelen.


    A good way to show off the purple line of potassium is to mix a bit of potassium chlorate and sugar and light it. This isn't really an indoors demonstration though.


    You won't see pink from anthing. Try some lithium for a nice red though.


    Copper acetate in methanol or ethanol is moderate for giving blue greens, but it's somewhat hard to tell the diffference from the alcohol flame.


    Indium gives a gorgeous, oddly saturated blue color, but it's not an everyday compound and teasing the color out is fairly hard. I think it is visible when I was burning a small sample of the metal in a propane-air flame.

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