Theophrastus

In terms of electrolysis, yes, it does work, however I find that the yield, unless you are using rather dangerously high voltages, is quite low. Also, while adding salts, will speed up the reaction, these result in impurities, for example sodium chloride will mean the production of chlorine gas. It certainly won't be enough to kill you, given the low voltages generally associated with amateur (non- industrial) electrolysis,though you'll generally be able to smell it, and I doubt breathing in chlorine, however trace the amounts can be good for one's health.

Well, if you don't want to use any strong alkali's/ acids, however are disinterested in using gallium due to its price, I think UC's idea, of magnesium and acetic acid, then using a dilute solution of sodium carbonate to remove any acetic acid vapour is probably what your looking for, in generating hydrogen.

Hey guys, to conclude this thread, assignment complete. I was rather simple with my model, grass, and modeled wetland- type ecosystem, along with gabions, simply to initially stabilize the shoreline, while the longer process of rebuilding ecosystems can begin. In my report I was more thorough, mentioning weathering (chemical and physical), acid rain (chemical weathering), nitrogen fixation (in a reference to general erosion), real situations in which human activity or unstable geological matter has caused excess erosion, why various structures are incapable of long- term erosion protection, etc.. Anyway, thanks for all the help with links and the like: it was most appreciated:-). I don't really know what is to be done with this thread. Perhaps it can be converted to serve further related purpose? ps: It's like recycling!

To UC: generally, when one uses water, as a solvent, one would dismiss the mist as water vapour, then again... Would sodium hydroxide remain dissolved in the water, even following evaporation? As for the reaction with hydroxide, that i've only seen done by teachers, as a sort introductory display, to captivate students for science class. I generally add hydrochloric acid to aluminum foil, as hydrochloric acid, costs a fair amount less where I live.

I go with insane alien, as sodium hydroxide and aluminum, is a viable method, given the fact that the boiling point of ionic compounds, is by nature, incredibly high, and thus you have little worry of attaining sodium hydroxide vapours. If you're really worried, you can use an excess of aluminum, so that all of the hydroxide reacts, or simply bubble it through water, where the hydroxide will dissolve, while the hydrogen (currently in its stable diatomic state) shall pretty much rise (bubble) through. You could perform a similar reaction with hydrochloric acid, or sulfuric acid and aluminum, of course. These of course have lower boiling points, but will similarly dissolve in water. As for the molten magnesium, in water method, yes, it does seem to glow a tinge, but there's no blinding light, burning out our sockets, or eyes...rather. (mind you, that might be rather fun:D) To Sherlock: Why not simply buy hydrogen? Becoause, generally I find that a lot of people generally only purchase chemicals when necessary. In other words when they cannot be made from scratch with ease. Hydrogen, is generally rather easy to make, so no problems there. Generally its those harder to make chemicals that are bought, like copper sulfate, silver nitrate, etc.

Yeah, similarly in the second question, theoretically, you could make a water molecule, using different isotopes. For example hydrogen can at times have no neutrons, one neutron, or two. (or three) These can all alter the atomic mass. The humidity question too is vague, as you pointed out D H, however, when I do multiple choice, I don't necessarily intend it to be the correct answer, but rather the answer that most closely fits the demands of the curriculum, and in all honesty, to have to think of testing in such a manner, really makes me question multiple choice,what with its fixed answers, and room to guess, and the ability to still attain credit for a guess, done at random. Though, based on the expected curriculum, the answers all seem to be correct, yes, in spite of fallacies within the questions

If your main aim is the generation of hydrogen, this can actually be done in various far simpler fashions. Rather than building a fuel cell, simply reacting sodium hydroxide, with aluminum, will yield adequate quantities of hydrogen, just be warned that the reaction is rather violent, so you should exercise caution. You could also produce hydrogen, by heating magnesium to a relatively high temperature, though be warned that it is natural for it to shed white sparks at this point, and then drop it in water. This shall produce hydrogen gas, and white, insoluble magnesium hydroxide, which once filtered out of the surrounding solution, you can use in further chemical exploits. Magnesium, for the amateur chamist, can easily be found in pencil sharpeners, as you can easily tell based on the weight whether its magnesium or steel. I recommend removing the screw and blade, as these are always made of steel. If you are unsure about the content of your sharpener, simply fill a measuring cup with an appropriate amount of water, then add the pencil sharpener. The increase in volume is the volume of the pencil sharpener, and then by finding out the weight you can find its density. You can then easily google the density of magnesium, and if your results seem to match, taking experimental uncertainty into account, you've found your metal. Best wishes, again- I hope this helps!

My best guess is that the asterisks indicate his selected answers, and he's current calling upon (I know, overly dramatic:-)) the community for feedback. Is feedback and criticism, of mistakes as long as the correct answer isn't explicitly given, adequate?

If you're getting your graphite from pencils, I recommend that you be warry that pencill grapphite, is actually coated in a layer of resin, so it adheres to the wood, however the heat of candle, is hot enough to remove this coating. If you try burning pencils (I've done it on occation, for lack of anything better to do!) You'll eventually notice the wood begin to curve, and split in two as a prominent line forms down the middle of the wood (the wooden portion, actually consists of two separate pieces), and anyhow, the process of burning is probably the simplest. As UC said, aluminum is a horrible conductor for a cell electrode. Copper, nickel, platinum and the like all work quite well, though it's true that the platinum is quite costly. I once bought some platinum coated nickel wire for electrochemical experiments, and even that didn't come cheap. Anyhow, most metals are actually quite available, if you know where to look. Most of my copper i attain, by displacing it from compounds, with iron (however, for obvious reasons, this isn't used as an electrode). Hobby shops, are generally a good source for electrodes at low prices. If you're not serious, and can deal with impurities, you can by means of electroplating remove the upper layers of coins and harvest metals like that. For example, nickels made before 1967 are made with 99.9% pure nickel. Pennies made between 1997 and 9 are actually made of zinc with a copper coating. To conclude, a little resourcefulness, can bring one a long way. If you're more serious about this however, there are tones of internet sites that supply these materials in better quality, purity and form. Some specialist hardware stores, can also be useful, in that regard. The hydrogen production on the part of the electrolyte can be problematic, and if you have some money, investing in some copper sulfate, to build something along the lines of a daniell cell, which is a simple intro to electrochemical cells, is recommended. Anyhow, happy experimenting, and best of luck!

In regards to blood stain analysis methods, aside from the basics, I've also heard that crystalization of the blood sample, can be used in some manner to determine the person's (or animal's) age. There was also something mentioned regarding the nature of the clotting- I would assume this would be during the administration of the necessary antiserum, that some aspect of the coagulation can be used to estimate age. I was recently reading a biology text, for lack of anything better to do, due to sickness (curse thee common cold!) and skimmed over a brief reference in the text towards forensic analysis of blood samples, though began to grow annoyed as it mentioned some less precise methods used to dissert things like age and race from a blood sample, making vague comments regarding a combination of crystallization, coagulation, etc., which given the level and detail of the text is understandable. But anyway, my question is, what method is generally used to estimate age, based upon a blood sample, and how does it work? Any ideas, or thoughts? As always, any assistance would be most appreciated. -Theo

Quite recently, I've been reading through a (impudent and screwy) biochemistry text, and was surprised that in contrast to the D and L method, used to classify enantiomers, based on how they react to polarized light, some mysterious R and S method is currently being used alternatively. Sadly, the text provides no reference to this second system. What is the R and S method based upon? And what do R and S even stand for (in relation to isomers of course, as in relation to myself, they would stand for restless and something else, which ought not be said (think along the lines of vulgar language, for a general idea)) ? Some answers would be most appreciated. Once again I ask that if anyone knows the name of a good introductory text by biochemistry I would be most gracious. (Theo goes off to make some silane gas in the lab to burn his already dilapidated text in)

Hey guys, So quite recently what with a bit of a sparked interest in biochemistry and human anatomy, I got myself a lovely biochemistry text, however reading through it, I've found numerous sections that are vague, and this is the first, and thus I have a question. I understand the nature of the formation of secondary structure in proteins, in the cases of alpha helices, and beta pleated sheets (and anti parallel), and from hat the text said, they are the most prevalent, however, then it stated the existence of other secondary structures, such as beta turns, and ohm loops, without bothering to reference formation, or the nature of these molecules. Can anyone please discern how these structures look, and how they form. Any diagrams would most helpful, as I've found imagination can only go so far. Can anyone also recommend some decent introductory texts for biochemistry and the like. All of this would be most helpful.

In terms of hardest, I'ld actually guess buckminsterfullerenes, as bulldewragh (sorry if I'm spelling that wrong:-() did, as for a recent project i had a rather brief interview with an architect who says that from a structural perspective, the buckminsterfullerene is the strongest shape. Though ultimately, I'ld go for the polymer that makes up a spider silk. Cool FYI for spiderwebs: If you were to take a length of spiderweb polymer, the length of a hair, and fix the two endpoints in space, the strand would be capable of stopping a jumbo jet in mid flight.

Assuming you mean the "black snakes," I find that its generally easier to make a mix of sugar, and baking soda. You then moisten the solution with ethanol, letting the ethanol dry a bit. You then apply a match. The baking soda (sodium bicarbonate) decomposes to produce water (sodium carbonate) and carbon dioxide, this pushes the reaction upwards. 2NaHCO3 > Na2CO3 + H2O + CO2 The molten sugar does not actively participate, but rather the molten sugar gives it form, as it charrs producing a black snake. Pretty neat. I'ld post pictures, but I have a minor problem with that, as you need to provide a URL. Is there any other way to upload photos? It be rteally useful for further posts.

Scientifically speaking, science fiction is a manner of speculation, which while all fun and good, I don't think that a subcategory should be made for it as this is a science forum, not a literary. If you're interested in writing a little bit of science fiction, and asking for opinion on the scientific parts of it, by all means, do so. I have no problems with that, and it would be an interesting idea, particularly with the rapidly expanding realm of quantum physics, string theory, and the like, though I don't feel the topic is broad enough to have its own subcategory. To ajb: I agree that speculations are perfectly adequate as long as they are done based upon concrete scientific fact. Honestly, I find that any reasonable speculation, easily has a place in any of the other subcategory. Let us say I am to make speculation regarding the nature of astatine based upon trends upon the periodic table. Such speculation, as long as I used concrete fact to back it up would be adequate. Obviously, Arbitrarily stating that I believe Astatine to glow pink, to have a gaseous form, and the ability to grant wishes, and work a typewriter, would be inadequate. This can obviously be sent to the garbage can P&S. To conclude, I think that any adequate speculation, can easily be applied in any of the other categories, or else, general science.

Lacking any better category, i've decided to use the General Sciences thread. Anyway, to go straight to the point. In cryogenics, chemistry, and other such endeavours, how are incredibly low temperatures achieved? I understand how high temperatures would work, (simple heating) however how can heat be taken away. I know based on the basic gas laws that increasing the pressure, would work, but how is it actually done? Are there pressurized gases at work, around a main tank, or is it done by some other means? Help would be most appreciated.

Alright, yes I admit that my intent had little to do with actual referencing, as I find the teacher in question to be rather ignorant, and really does not care to check sources and citations. I was just interested in credibility, and whether it is really fair that as early as elementary school, wikipedia is considered a greatly flawed source, to the extent that it is banned, and the like. I particularly like Hermanntrude's idea; finding the initial reference articles on wikipedia, and using them as research material. I'll do that from now on. Cool responses everyone!

Hey, quite recently I have been commanded to work on an assignment for school, and I've noticed a trend that seems to increase in the number of times it recurrs. My friends and I are all wikipedia buffs, and as such, we often use wikipedia as a fail- safe method to get a general picture, for research, before we start to narrow our focus, however, more and more so, we find our sometimes unnerving educators, explicitly stating that wikipedia is prohibited as a research tool, as all of the sites bear no rational information. This annoys me, as I find wikipedia to be generally accurate, with rare exception, and am actually very interested in their cause. So, I am preparing a rhetoric arsenal in my battle. Though, I do have a question. Why is it that educators are so annoyed with wikipedia, and why is it being attacked in the mainstream, as a far- from reputable source of information? Secondly, a teacher told me that the information on wikipedia changes every 7 minutes, this of course due to the vast amount of knowledge, and to people adding info, but its just as on this forum. Even if a wrong answer is stated, people quickly come to correct it. Right?!?

Personally, I strongly, discourage, for your own safety, playing around with liquid hydrocarbons and ethers. There's a reason why tanks of butane have lovely insignias that look like this: Alternatively, dimethyl ether is often used in thermometers, but your yield, would be pitiful, and once again, ethers too, are incredibly violent. I'm too lazy, though based upon the chemicals you desire to extract, you can calculate their polarity, and then choose an adequate solvent, for the chemicals that you want. Of course, you shall by nature (quite literally) attain quantities of chemicals you don't want, but they are most likely safe, in trace quantities, or both.

On the initial subject, gallium melts at around 30 degrees celsius, and as such, its generally a less toxic alternative to mercury, though it is still mildly toxic, and stains, so one should still take care in handling it. Its density, is about 6 times that of water, so it can be used to sort stuff. If a thermometer uses a liquid metal, which isn't mercury, (mercury- free) its probably a gallium alloy, that's used. I wish I had a substantial amount of mercury or gallium. Liquid metals are pretty cool... (suddenly attains the idea to market a mercury theme park:" try our mercury slides! Just try not to get a tumour while you're at it!" Ah, neurotoxins... In regards to the densest material, I'ld guess it to be some manner of fun radioactive element, though that would be rather unstable (for obvious reasons). Though I've heard that hydrogen at temperatures relatively near absolute zero, like those that can be achieved in a cryogenics lab, can become incredibly dense.

Ignore the following post, it is a product of my own stupidity and forgetfulness! Bah! (Runs off in a huff, with potassium cyanide, and fish food...)

As Hermanntrude said, the copper and magnesium sulfate do not react, and if they do, due to the copper's 'excited' state, the magnesium will gladly displace the copper, and the solution shall return as it was. In terms of testing the identity of the precipitate, I'ld guess that it may be copper hydroxide, though the colour of hydroxide isn't exactly green. Is the colour consistent throughout, as if it isn't there could be a bit of carbonate, due to further oxidation. Hydrated copper chloride sounds more like your description, but copper chloride is soluble, and generally, ions don't magically appear from thin air. It could also simply be due to impurities, so I recommend that any information you have, particularly if you've discovered your electrode to be copper plated (its happened to me before ) you ought to elaborate on your layout and let us know. You should also do a flame test, with this green precipitate, to see if its a copper compound. If so, try adding hydrochloric acid, and if you get the characteristic colour of copper chloride, It's most likely hydroxide. (copper II oxide is black) If you find that it isn't a copper compound, in which case, I can't really help. Though if you need help, I recommend mentioning a little more about the layout. Where did the idea of it being a nickel salt come from?!?

(adjoin with previous post) Having filtered out most of the solution, leaving the rest to boil off in the beaker, I found a rather interestinhg sight. I'm rather annoyed with my yield, and as such, have given up on making hydroxide, in such a fashion. Still, I remain interested in what I have prepared finally. I think that the orange is likely to be copper, and the white crystals near the top of the beaker, leftover magnesium sulfate. The whitish bluish substance on the bottom, covered in copper, I think, is a mix of copper hydroxide, and carbonate, formed through further oxidation, though the colour worries me a bit, as it also looks a bit like copper oxychloride, however, as no sodium chloride salt was added, I doubt it. I'll soon add some hydrochloric acid to the beaker, and if my guesses are correct, the solution should turn the blue colour of copper chloride, if not... well I haven't really thought of that. Any last- minute thoughts are quite welcome. If all goes well, I'll post my results this evening.

Essential oils, are volatile oily compounds, found within various trees and plants, which are generally extracted from them, by selective condensation. I agree, with Hermanntrude however, that if you are going for a chemical means of extraction, you ought to isolate the compounds you desire, directly, or by their type/ functional group, and then go from there. You metioned perfume, so is it that you desire jasmone, or what types of other compounds?

Oh, one other thing I forgot to mention, given I began relatively late, time is an issue, however I have altogether, about 2 and a half weeks, would this be adequate for the species in question?