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hermanntrude last won the day on December 11 2009

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About hermanntrude

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  1. however, steam has a different refractive index to air so it'd be visible by the way objects behind it would appear distorted. transparent, yes, invisible, i'd say not.
  2. you might be able to make a polyatomic ion out of xenon atoms minus a few electrons, or even maybe just one. I think [Ne2]+ is predicted to be stable
  3. this is one of the things i tried. it failed horribly. i think the headspace is necessary to allow cooling of the water vapor. i did notice that with a smallish headspace was best, and gave heavy bubbles which after a few minutes became lighter. i'm going to buy a cylinder and be done with it, but i've also decided to get rid of the horribly rusty chlorine cylinder first
  4. I tried all the above suggestions and also a few more. I managed to get floating bubbles by using zinc and fairly concentrated H2SO4 (created by putting zinc in water and adding swigs of conc acid as needed), but it wasn't reproducible... the bubbles floated sometimes and sometimes not. And i could never get the bubbles to break off of the larger mass, they just made snakes which stood up
  5. the bubbles are already doing that. I have a side-arm conical flask which has the acid and metal in, with a stopper in it, a tube running from th side arm to another conical which has an inlet tub below the surface of some soapy water and an outlet leading to a small glass funnel. the bubbles are probably a centimeter or so in diameter on average
  6. The bubbles are smallish but should be big enough. i've tried a number of setups but all involving an acid and a metal (i've settled on 1M HCl and Mg for speed of delivery without getting dangerously hot), and in each case i've run the hydrogen through a separate bubbler. I'm thinking about this a lot and i'm thinking the only thing it can be is water vapor weighing down the bubbles. The bubbles are of comparable size to those in videos ive seen. I found only one video involving floating bubbles which didn't use a cylinder, and that used aluminum, which I will try tomorrow. i'm thinking perhaps aluminum has a lower enthalpy change for the reaction with HCl and so less water gets vaporised. I'll also try running it through a longer tube before bubbling it and if i get desperate i'll try a drying tube
  7. I've been attempting to recreate this experiment (link), but without using a hydrogen cylinder. The only problem is, that no matter which acid or metal i use, no matter how fast i generate the gas, my bubbles don't float. They burst into flame nicely but they don't float. I'm not sure what's causing the bubbles to be so heavy... is it gaseous water?
  8. OK this is a volumetric analysis question, which always goes like this step 1: calculate number of moles of known substance used step 2: use stoichiometry to find number of moles of unknown substance used step 3: use information from step 2 to find whatever it was you were asked for step 1 is simple. find the number of moles of HCl. This involves the equation c = n/V step 2 requires you to write a balanced equation for the reaction of [ce]Na2CO3[/ce] with HCl (remember that the waters of crystallization will not be involved in this reaction so you can leave them out). step 3 involves using the number of moles of [ce]Na2CO3[/ce] from step 2, along with the original mass of the solid with the waters of crystallization to calculate the value of x in [ce]Na2CO3.xH2O[/ce]
  9. most carcinogens work in small quantities over long periods of time. A single dose just once is probably not going to be trouble.
  10. awesomeness
  11. there's no harm in stating the obvious, as well, in nice clean scientific terms. Physiology is a science too, after all.
  12. technically, a guy making moonshine is several things. A biochemist, a sythetic chemist, a brewer, a criminal, and in many cases, foolhardy.
  13. A real help in understanding stereochemistry is to use a molecular modelling kit. If you dont have one or can't afford one, many institutions (schools, colleges, universities) will allow you to borrow one for a while. If that isn't true, try using cocktail sticks and pieces of sticky tack. Use coloured markers to distinguish between cocktail sticks
  14. my advice to students who are concerned about organic chemistry is do some review the basics are vital for understanding organic chemistry. here's a short list of stuff you'll find useful to remember - skeletal diagrams - aromatic rings - isomerism - formal charges - electronegativity - chatelier's principle remember to ask lots of questions, and be prepared to spend a lot of time working on assignments and review your notes while you study the course (not just before the exam!). There are some really good chemists here who will be able to help if you're getting stuck, but remember they usually take their time in answering, so study early!
  15. Cu+ has an annoying tendency to oxidize to Cu2+. i don't know if that might be trouble in the suggested reaction...