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Everything posted by raivo

  1. In my humble opinion such reaction to the methanol spill was surely an overkill. Not that this kind of spill does not need attention - it surely does - but funny thing is that university with all its educated minds is not able do deal with it and so much help from other institutions is needed. This of course is not specific to your university but is more likely modern fashion.
  2. I do not think that some of future great discoveries can not be made by single individual without expensive lab. There is another problem though. Discoveries are very rare. Its something like winning in lottery (and you must be genius to be able to play). There is no big discovery for everyone but something like 1 for 100 000 who might be able to make one. This is if we are talking about discoveries which make you famous. If fame is not required then there is lot to be discovered. Modern science does not study everything. It tries to fill gaps in theory or to improve modern industrial processes. If one just wants to discover new methods of making something in home lab then its not that hard to discover some efficient preparations that are not known anywhere in the literature. Chances are high just because all those billion dollar labs explore completely different things.
  3. For photographing there are special CCD modules. Even professional astronomers use them now. Good telescopes take some time to set up, they also need good weather conditions. IMO its better to buy two instruments: one relatively cheap and small which is fast and convenvenient to set up (for example 12x binoculars with wide input aperture and sturdy stand) and another - decent telescope, for photographing and precision monitoring.
  4. Maybe network card or drivers? Years ago i had similar problem with Windows 98. All worked fine but windows crahsed always after i used internet for some time. Maybe it even rebooted itself. I can not recall what exactly i did to overcome this but it was something with network drivers or ADSL software.
  5. As far as i know phosphoric acid will work for all common volatile acid synths but as you said, it will ruin glassware. I read from old book that oxalic acid can be used instead of sulfuric acid for such reactions. It is nonvolatile and reacts very slowly (if at all) with boiling HCL or HNO3. Yields will probably be low as oxalic acid is rather weak acid. I have not tested this myself so maybe it does not work at all.
  6. As far as i know microscopic explorations in metallurgy are not just using microscope but mostly of preparing metal surface. If i recall correctly, metal piece is cut and polished, then etched with special reagents (some of which contain notorious HF). This makes crystal structure of metal to stand out. Processed piece of metal is studied with microscope which, indeed must be of highest quality. I think that unprocessed metal surface is not worth of viewing at more than 100x magnification because there are not that fine details. In fact 40x or even 20x should be enough to see everything that there is. Still, i am not sure, maybe someone can write more about how metallurgical microscopes are used and what magnifications are actually useful. One link for stereo microscopes (not cheapest but rather good): http://scientificsonline.com/category.asp_Q_c_E_422940_A_Stereomicroscopes You should also search for "stereo microscope" in e-bay. It just got 614 hits.
  7. My humble opinion is that stereo microscope is best for your hobby. I do not recommend to buy video microscope if you can not test it first. Its nice to see picture in screen but it may actally show less detail than you expect. Video microscopes are very usefull only if group of people must work together with one specimen. Stereo microscopes are not only used in biology but also in field of microelectronics to inspect fine parts of printed circuit boards and also in geology. Stereo microscopes are less tiresome to use than common types and images are better to understand because of stereoscopic view. I know nothing about metallurgical microscopes.
  8. Impact and friction make mechanical connections (batteries with rest of circuit) conduct better as oxide and dirt layers in contact surfaces will get damaged.
  9. I'd rather agree wiht Bettina here. There is lot of insulting not because idiocy of those who ask questions but because of prejudices (or even strawmaning) of those who give answers. For example if someone tells that in his opinion particular scientific term makes false assotiations he/she may get lot of insulting because others interpret his statement as proof of not knowing science. It would not be hard to collect long list of examples of insults where victim surely is not idiot, just his statement was interpreted so that he/she can be shown as idiot. In my opinion not "idiots" should be insulted but those who maliciously behave like idiots. In perfect world one should feel very safe to ask anything that he/she does not know. Path from "not knowing" to "knowing" is much more valuable than "knowing allready". In my opinion those who always want to know more and every day learn something new are worth more than those who once, ten years ago learnt something and now still are proud with that. I have noticed this problem in other forums as well. For example good old Sciencemadness has somewhat changed in last year or so and anything that can be interpreted as idiocy will surely be thought to be. In older times this was not so. I do not want to blame moderators. I suppose they just get tired when the same simple questions are asked tens of times again and again. Still, if this problem could be solved many forums would live longer and would give more answers to the questions that people really think of.
  10. Similar system can be designed with any microcontroller which has multicannel AD converter built in and serial port to communicate with PC. You need small program in microcontroller flash memory and another in PC to get beatiful and easily readable output (otherwise you can only save raw data with some general terminal program). Some opamp circuits are needed if output of sensors is not directly compatible with 0..5V AD converter input. It's quite common to build similar system (for example for collecting weather data) by single individual at home. Nothing complex here just long line of small things that must be done correctly to get everything working.
  11. Encrypted passwords can not be decrypted but one can write program that takes random words and encrypts them with same one-way algorithm. If certain word gives identical result then password is not secret any more. This is only minor risk if passwords are too complex for random guessing. In my humble opinion this case is not worth very much attention especially if no other attacks will follow.
  12. Formulas that are used to calculate exact positions of planets and moon are very long. You could also write equations for the 10 simple particles that can collide and change directions and speeds by simple laws . Suppose they are in the box and each of them has different initial speed and direction. If you want to know what are exact positions of particles after some time when, say, 1000 collisions have occured then you will get very long formula.
  13. I, too, like Woelen's idea, especially with Martin's correction. Whois.net tells that religionsforum.net is available:
  14. Suppose you claim something and then your opponenet says: "I know you are wrong but... ... i have no time to explain or ... those expalnations are so complex that you will not understand or ... i could explain but this does not interest other readers or ... i can not explain because it contains information that should not be disclosed or whatever like these, and then goes on as if he had proven that you are wrong (of course he could be right but no proof given and no way to discuss it further). How this is called?
  15. One sample per 1 microsecond is not that high. For example common video AD converters use 20 or 30x higher sampling rates. Unfortunately i do not know of microcontroller that has such AD converter built in. It may be that you actually do not need continuous sampling (and transfering everything to computer). Cycles with, say, 2048 samples may do the job. In that case you can use common serial port for computer connection which makes things a lot easyer. You also my not need direct graphics output as everything could be written to file that can be converted to visual representations afterwards. Such system can be built using logic circuits to make AD to run standalone and write its output to FIFO or RAM. After complete sampling cycle microcontroller reads memory content and sends it to PC.
  16. Do not know if this is the cause but barium nitrate is about 3.5 times less soluble than chloride ( about 10g in 100ml water @ 25C)
  17. I do not know about 100% acetic acid but those that i have (various from 80% to 98%) are quite hard to crystallise. For example one sample in PET bottle did not crystallise although was in fridge at -18C during two months. After using some of it for experiments and placing into fridge again it crystallised after some hours completely. Now, again, i liquified it and after this it stays more than week in fridge without crystallisation. Another day I pipetted 98% acetic acid. Room temperature was 20C but glassware was somewhat colder and acetic acid crystallised completely inside pipette even before i managed to fill it completely! This was scary as i did not expect something like that! So acetic acid does what it likes to do. At least if we talk about crystallisation.
  18. Its not first time when telepathy experiments give positive results. Problem is that these tend not to be repeatable. Now and then someone or some group of researchers gets positive results then others try to repeat but most of them get no correlation. Then after some time someone again gets positive results but he can not describe what exactly he did differnetly. So most common explanation is that positive results are nothing more than unknown errors in experiment design. Lets wait and see if others can repeat these results.
  19. I have used this many times. Just place end of gas delivery tube some millimeters above water level. Adjust this distance when level of liquid increases. In fact no stopper is needed for the bottle where gas is dissolved, it just has to have high walls. This worked well when i made HCl, HNO3 and HBr. Although it seems that there is not much gas lost you need fume hood (or very good ventilation at least) as otherwise you can be exposed to escaping gases.
  20. There are almost no bright and reliable colors for cloth that are based on inorganic salts. Using plants has the same problem. Breakthrough in dyeing industries was discovery of coal-tar dyes. These were various compounds containing one or more benzene ring (coal-tar was major source of benzene in these days). You, too, need to prepare organic dyestuffs if you want to get beautiful and reliable results. Most of practical organic chemistry books contain some sample synths. Problem is that good organic chemisry setup is needed for this and you have to deal with some very toxic precursors.
  21. In my opinion NaOH is much better. To make 3 mol of hydrogen you need 80g NaOH or aproximately 0.65l concentrated (33%) HCl. What is cheaper? What is easyer to get? In my case NaOH. [math] \ce{2Al + 2NaOH + 2H2O = 2NaAlO2 + 3H2} [/math] [math] \ce{2Al + 6HCl = 2AlCl3 + 3H2} [/math] It is good idea to be cautious and wear some eye protection as NaOH can be much worse to your skin than HCl -is.
  22. Hydrogen flame emits very little light. If hydrogen happens to burn without explosion then fact of combustion may remain unnoticed.
  23. IIRC calcium sulfate is somewhat soluble in aqueous ammonia but i do not know what chemical changes cause this.
  24. Some carbides have very high melting and boiling points: ZrC mp 3500C, bp 5100C. TaC mp 3800C, bp 5500C Some substances with high melting point become soft like lead much before melting and others may start to react with oxygen and other gases even below 1000C. In practice graphite, carborundum (mp 2800C) and platinum (mp 1770C, bp 3800C) are often used where high heat occurs. Certain carbides and some oxides like Al2O3 (mp 2050C) and MgO (mp 2825C, bp 3600C) are also very common. Tungsten (mp 3420C, bp 5680C) and molybdenum (mp 2620C, bp 4630C) bear high heat very well but only in oxygen-free environment. There are also lot of special alloys that are incredibly strong at 1000C or 1500C but have lower melting points than their constituents.
  25. You can make some CO2 by dissolving citric acid in water and adding some sodium carbonate or bicarbonate. You can make citrates by reacting it with some freshly prepared carbonate or hydroxide but AFAIK citrates are not particulary interesting compounds.
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