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Everything posted by hermanntrude

  1. hermanntrude


    http://chemistry.about.com/library/weekly/aa020603a.htm there's a bunch of gas syntheses in there. easier than messing with resonant frequencies
  2. yes thanks for that. Here we see the difference between my definition of "best" and yours. My definition included a consideration of safety and responsibility to my students. Anyway, if it turned in a circle it'd be moving into and out of the axis of the waves. The wavelength wouldnt be easy to pick up from the pattern derived, i expect.
  3. have a lok at valence bond theory as well. It explains it a bit further and you'll understand better. If you can stand even MORE, try molecular orbital theory. benzene is a bit of a challenge for all of the bonding theories but the more advanced the theory the better the explanation gets
  4. hermanntrude


    any molecule has multiple resonant frequencies. Which ones are you looking for and why?
  5. the easiest way to get the sulfate solutions would be to cut your strips in half and dissolve one of each in some sulfuric acid... does your school/college/university chemistry lab have sulfuric acid? any cell you can make will light up for more than a few seconds assuming the emf is high enough for the bulb. the easiest method would be to buy a lemon, use the copper and zinc strips as electrodes (which you shove into the lemon) to power the bulb. I doubt it'd be very bright but you certainly can get a voltage (emf) from that.
  6. not mad. When I wrote C-C i meant to signify any bond, not specifically single bonds. the bonds (all six of them) are about one-and-a-half bonds in fact. I don't have any fonts with a way of signifying that so i just represented it as a single bond. Sorry to confuse you.
  7. your Ka value will probably solve the problem, i think. let us know what u get
  8. there are websites which list the quantities in which you need to mix ice, water and salt to get various different temperatures, for use as ice-baths in temperature sensitive chemical syntheses
  9. for a start, under normal conditions, 1,3,5 cyclohexatriene doesn't exist. The difference is that the three double bonds are spread out across the six possible positions, in a phenomenon known as resonance. The reason you got the bond-length explanation before is that if the 3 double bonds were stuck in just one place (like in the imaginary 1,3,5 cyclohexatriene) then 3 bonds would be short and three would be long, but benzene contains six equal length C-C bonds. The true story is a bit more in-depth than that. If you want to know more, first look up resonance and then look up valence bond theory, then look up each of those with reference to benzene.
  10. tell me, what were your original choices? was one of them NaCl? because you can get down to about -20°C with that. I'm not sure that a strong freezing-point depression will help you very much if the reaction isnt endothermic enough. Perhaps you could refer to the CRC handbook and find the deltaH of dissolution for your compounds?
  11. I havent yet tried it. I ordered the oleic acid from my local pharmacy but i wont be back in my lab till monday, and i might not have time ti try it out till later in the week. I am hoping that having a laboratory and some pure chemicals will help me get a better result. I will be disappointed if it doesnt spike. I also have access to some neodymium magnets which should help too. There's another version which is water based but the surfactant is tetramethyl ammonium chloride, which you would definitely need a laboratory for. I expect that most surfactants would do the job but the rest of the formulation would need to be "tweaked" to get the right consistency. I'll let you know when it's done. What i'm hoping is that i can bottle it and bring it out every year as a demonstration.
  12. I'd be highly suspicious of the ones posted on the web anyway, since they all knew what the speed of light was supposed to be before they did the experiment and probably wouldnt have posted it unless they felt their results were correct. I wouldn't be at all surprised if many of them re-measured their wavelengths a few times before deciding on a "final" answer.
  13. the ideal scientist would have a pHd in all three sciences. Although that in itself would make him or her non-ideal, since he/she would be about 40 years old when starting his/her first job and probably also on the brink of suicide. No one science can stand on its own. I'm a chemist so i tend to believe that chemistry is the most important science, but i often find myself wishing i knew some more physics or biochemistry. I remember I once saw a quote on a notice board which said this:
  14. the wave is standing, yes but that doesnt mean the radiation isn't moving, it just means the peaks and troughs remain stationary. The speed of light varies in different media. If the chocolate melts that must be because at some points the light travels through the chocolate. If light travels through the chocolate it must be slowed down. I don't see how that conclusion can be escaped
  15. Lance, anyone who has watched a documentary on sharks will have heard your theories on what provokes a shark attack. they are not new. sorry to rain on your parade.
  16. jolly ranchers can almost certainly be considered to be essentially 100% sugar, probably glucose and sucrose. since this is a 10th grade experiment we can also probably guess that the acid solutions are HCl and the alkaline solutions are NaOH. is this correct paved?
  17. very good video I agree. I still think that we should expect some slowing of the speed of light from the refractive index of chocolate, although yes the larger part of the error is bound to be the imprecision in the frequency of the magnetron.
  18. look for information on the common ion effect and the salt effect.
  19. well the density is a factor, and it allows us to determine roughly what to expect. I used fairly large chunks of chocolate and the wave is definitely inside the chocolate for some of the time, certainly not only in air, or the chocolate wouldn't melt.
  20. OK I read on another part of the forum about the determination of the speed of light using a chocolate bar and a microwave, My and my students tried this out today and came up with a value of 2.2 x 10^8 m/s. originally I thought that most of this error comes from the dodginess of the measurement and from the inaccuracy of the frequency on the back of the microwave. however, I asked my students about the sources of error and one came up with a very interesting thought: The speed of light varies in different materials. In water the value is about 2 x 10^8, apparently. So if this is the case, and chocolate is more dense than water (i think), so we would expect a speed of light in chocolate slightly lower than 2. BUT, we cannot assume that the microwaves remain in the chocolate during their entire traverse through the space inside the microwave. so the value we have measured is some kind of average speed of light during a travel through both chocolate and air. My colleague also tells me that the refractive index of chocolate is a value often measured in the chocolate industry for quality control... the things you learn... thanks to the fellow member who first posted about this... i'm just off to search for your name so i can acknowledge you properly. EDIT: the member's name was mooeypoo. thanks muchly to you for your idea. it worked beautifully. Here's the link to her thread
  21. ask a sensible question, get a sensible answer. currently, the only possible answer to this question is "please tell us what you mean" Think about specifics. Which machine? measure the curve how? what do you want to know. be precise.
  22. 1 and 3 are good ideas. Not too sure how well #2 will work but you should be able to rely on #s 1 and 3. You'll find melting points in the aldrich catalogue or in the CRC handbook, both of which your school/college/university should have. pKa values should also be in the CRC handbook.
  23. I once wrote out a version of the periodic table with the f-block in it's correct position. I made a mistake in placing Sc and Y, though. Despite that it taught me an awful lot about what the periodic table really shows and how. If I find it, perhaps i'll scan it in.
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